The Human Genome Project
The Human Genome Project is a worldwide research effort with the goal of analyzing the structure of human DNA and determining the location of the estimated 100,000 human genes. The DNA of a set of model organisms will be studied to provide the information necessary for understanding the functioning of the human genome. The information gathered by the human genome project is expected to be the source book for biomedical science in the twenty-first century and will be of great value to the field of medicine. The project will help us to understand and eventually treat more than 4,000 genetic diseases that affect mankind. The scientific products of the human genome project will include a resource of genomic maps and DNA sequence information that will provide detailed information about the structure, organization, and characteristics of human DNA, information that constitutes the basic set of inherited "instructions" for the development and functioning of a human being. The Human Genome Project began in the mid 1980's and was widely examined within the scientific community and public press through the last half of that decade. In the United States, the Department of Energy (DOE) initially, and the National Institutes of Health (NIH) soon after, were the main research agencies within the US government responsible for developing and planning the project. By 1988, the two agencies were working together, an association that was formalized by the signing of a Memorandum of Understanding to "coordinate research and technical activities related to the human genome". The National Center for Human Genome Research (NCHGR) was established in 1989 to head the human genome project for the NIH. NCHGR is one of twenty-four institutes, centers, or divisions that make up the NIH, the federal government's main agency for the support of biomedical research. At least sixteen countries have established Human Genome Projects. The Office of Technology Assessment (OTA) and the National Research Council (NRC) prepared a report describing the plans for the US human genome project and is updated as further advances in the underlying technology occur. To achieve the scientific goals, which together encompass the human genome project, a number of administrative measures have been put in place. In addition, a newsletter, an electronic bulletin board, a comprehensive administrative data base, and other communications tools are being set up to facilitate communication and tracking of progress. The overall budget needs for the effort are expected to be about $200 million per year for approximately 15 years. Lasers are used in the detection of DNA in many aspects of the project; a very important use is in sorting chromosomes by flow cytometry. Lasers are also used in confocal fluorescence laser microscopy to excite fluorescently tagged molecules in genome mapping, in addition to other mapping uses. In diagnostic applications, lasers are used with fluorescent probes attached to DNA to light up chromosomes and to create patterns on DNA chips. From the beginning of the human genome project it was clearly recognized that acquisition and use of such genetic knowledge would have momentous involvements for both individuals and society and would pose a number of consequential choices for public and professional deliberation. As Thomas Lee writes, "the effort underway is unlike anything ever before attempted, if successful, it could lead to our ultimate control of human disease, aging, and death". Whatever its justification, the human genome project has already inspired society with the hope of "better" babies, and one way to deploy pragmatism in the analysis of genetic engineering is to look at this promise of "better" babies in its social context: parenthood. Parents hope for healthy children and, if they could afford it, make choices (such as choosing parental care) to help "engineer" healthier babies. Genetic engineering seems in this respect to offer the brightest hope for parents. Through germ-line therapy, disastrous, but genetically discrete diseases, such as Huntington's and cystic fibrosis could be removed from the DNA of the egg or zygote. Clearly parents would follow the model in choosing to avoid a short, painful life for their children. Another more reasonable fear is that we have not the slightest idea what we are doing and ought to avoid making hasty choices. Hybrid varieties are often impossible to protect from the complexities and dangers of nature. In the human condition, this is the possibility of making an error and creating a genetically advanced baby who cannot cope with an imperfect world. While much of society reports a willingness to modify DNA for the purpose of heightening intelligence, education about genetics and medicine is still in its beginning. Jonathan Glover argues for a "pragmatism of risks and benefits", writing that, "The debate on human genetic engineering should become like the on nuclear power: one in which large possible benefits have to be weighed against big problems and great disasters". One significant element is the assertion that genetic engineering is radically different from any other kind of human medicine, and constitutes interference in a restricted area, trying to "play God". As Robert Wright notes, "Biologists and ethicists have by now expended thousands of words warning about slippery slopes, reflecting on Nazi Germany, and warning that a government quest for a super race could begin anew" if genetic engineering ventures "too far".
lunes, 15 de enero de 2007
*Cloning and Nuclear Cell Division
Cloning and Nuclear Cell Division
The societal issue being addressed in this article is the cloning of humans and nuclear cell fusion. This question lingering into every household…Should we be playing God? This question has substantial points on each side. Some people think that we shouldn’t be manipulating nature’s creations ,and we should leave things the way they are because that is the way things are meant to be. Other’s oppose that jurisdiction and state that we can rid the world of cancers and tumors and quite possibly save lives. Others don’t believe strongly either way, though believe in restricted means of distinguishing forms of cloning using safe and well-tested means. Research on human embryos has been minimal over the past few years because of the lack of money from the government to perform sophisticated experiments in this area. “In the 1980's and early 90's this research was banned by both the Ronald Reagan and Bush administrations due to pressure from the pro-life factions of the Republican party.” The societal issue addressed is expressed from all point of views, and the following will further strengthen and help you understand their points. “The procedures used in human embryo cloning have been around for many years, and have been used in the cloning of cattle and sheep embryos, for the production of animals with known genetic traits. The news of human embryo cloning did not surprise many people in the scientific community, but it shocked the general public.”(psu.edu) Many biologists believe that they have a personal duty to the improvement of society, perhaps even a moral obligation. To this end the techniques of embryonic cloning and alteration have been offered to society as an option for the improvement of humanity. Doctors hope that by being able to study the multiple embryos developed through cloning, they can determine the causes of spontaneous abortions. Contraceptive specialists believe that if they can determine how an embryo knows where to implant itself, they can develop a contraceptive that would prevent embryos from implanting in the uterus. This all means that cloning would help our future and help us further understand our human bodies. A defensive statement for this would be that these scientists are creating genes and are pushing the scientific envelope. How much further can they go? What if they create something that evolves to withstand forces of nature and science? Anything is possible when you play with something you fully don’t understand. Cancer research is possibly the most important reason for embryo cloning. Neuro-Oncologists believe that embryonic study will advance understanding of the rapid cell growth of cancer. Cancer cells develop at approximately the same speed as embryonic cells do. By studying the embryonic cell growth, scientists may be able to determine how to stop cancer growth in turn. Some ask is it worth the risk? Others oppose this question with, is it worth the risk to not know it’s full potential and how it can help us?. These questions are few of the hundreds now argued throughout the world in courts and legislatures.
The societal issue being addressed in this article is the cloning of humans and nuclear cell fusion. This question lingering into every household…Should we be playing God? This question has substantial points on each side. Some people think that we shouldn’t be manipulating nature’s creations ,and we should leave things the way they are because that is the way things are meant to be. Other’s oppose that jurisdiction and state that we can rid the world of cancers and tumors and quite possibly save lives. Others don’t believe strongly either way, though believe in restricted means of distinguishing forms of cloning using safe and well-tested means. Research on human embryos has been minimal over the past few years because of the lack of money from the government to perform sophisticated experiments in this area. “In the 1980's and early 90's this research was banned by both the Ronald Reagan and Bush administrations due to pressure from the pro-life factions of the Republican party.” The societal issue addressed is expressed from all point of views, and the following will further strengthen and help you understand their points. “The procedures used in human embryo cloning have been around for many years, and have been used in the cloning of cattle and sheep embryos, for the production of animals with known genetic traits. The news of human embryo cloning did not surprise many people in the scientific community, but it shocked the general public.”(psu.edu) Many biologists believe that they have a personal duty to the improvement of society, perhaps even a moral obligation. To this end the techniques of embryonic cloning and alteration have been offered to society as an option for the improvement of humanity. Doctors hope that by being able to study the multiple embryos developed through cloning, they can determine the causes of spontaneous abortions. Contraceptive specialists believe that if they can determine how an embryo knows where to implant itself, they can develop a contraceptive that would prevent embryos from implanting in the uterus. This all means that cloning would help our future and help us further understand our human bodies. A defensive statement for this would be that these scientists are creating genes and are pushing the scientific envelope. How much further can they go? What if they create something that evolves to withstand forces of nature and science? Anything is possible when you play with something you fully don’t understand. Cancer research is possibly the most important reason for embryo cloning. Neuro-Oncologists believe that embryonic study will advance understanding of the rapid cell growth of cancer. Cancer cells develop at approximately the same speed as embryonic cells do. By studying the embryonic cell growth, scientists may be able to determine how to stop cancer growth in turn. Some ask is it worth the risk? Others oppose this question with, is it worth the risk to not know it’s full potential and how it can help us?. These questions are few of the hundreds now argued throughout the world in courts and legislatures.
*Charles Darwin And Imperialism
Charles Darwin And Imperialism
England went through dramatic changes in the 19th century. English culture, socio-economic structure and politics where largely influenced by the principles of science. Many social expressions occurred due to these changes. Transformations which categorized this time period could be observed in social institutions; for instance: the switch from popular Evangelicalism to atheism, emergence of feminism and the creation of new political ideologies (Liberalism, Conservatism and Radicalism). These are just a few of the changes that took place. All of this social alteration can be attributed to the importance of science. The English people began to trust more in empiricism and logical thought than in faith and glory of the empire . One who contributed greatly to this transformation was Charles Darwin. In his two most famous works, The Origin of Species and The Decent of Man, Darwin introduces the concept of "the survival of the fittest" and "natural selection". The Darwinian ideas introduced into English society justified a great number of political policies and social movements. England at the turn of the century was still a largest power in the international system. The English perceived, through the justification of Darwinism, they were fit to be the imperial hegemon in the world. The issue this essay will deal with is Imperialism and how Darwinism justified its practice. Darwin argued in his work, The Decent of Man, "When civilised nations come into contact with barbarians the struggle is short except where a deadly climate gives its aid to the native race. . . the grade of civilisation seems to be a most important element in success in competing nations."(Darwin, Decent of Man, p. 297). In this observation, Darwin connotated superiority to civilized nations. In this same work, he referred to the indigenous people as "savages, barbarians and tribal men". This immediately transfers a condescending attitude toward the "uncivilised people". Darwin classified them as tribes while the English and other Aryan cultures were a race. These claims of basic inequality gave the English the "jurisdiction" philosophically, to exploit the colonies to a greater level than previously attained. The drive to "Christianize" the colonies was abandoned, politically. The view shifted from "owing the primitive world" education and Christianity, to a more self-interested "we English are naturally better". Therefore, the we should be exploiting you, because, that is why you are here. Charles Darwin had a tremendous amount of influence on the scientific community and the English population. It can be seen that Darwinism played a large part in justifying the imperial behavior of England. Darwin's studies on nature and the behavior of animals had unlocked "Pandora's Box" in a manner of speaking. He studies reveal how close to nature humanity really is. The English empire quickly saw themselves as a dominant predatorial species of the world. In conclusion, the English empire used Darwinian concept to justify the on-going process of imperialism. Charles Darwin's ideas elevated the ego's of the English people to over-estimate themselves socially and globally. The affects of Darwinism can be seen throughout the spectrum of social interaction both in the animal kingdom and human society.
England went through dramatic changes in the 19th century. English culture, socio-economic structure and politics where largely influenced by the principles of science. Many social expressions occurred due to these changes. Transformations which categorized this time period could be observed in social institutions; for instance: the switch from popular Evangelicalism to atheism, emergence of feminism and the creation of new political ideologies (Liberalism, Conservatism and Radicalism). These are just a few of the changes that took place. All of this social alteration can be attributed to the importance of science. The English people began to trust more in empiricism and logical thought than in faith and glory of the empire . One who contributed greatly to this transformation was Charles Darwin. In his two most famous works, The Origin of Species and The Decent of Man, Darwin introduces the concept of "the survival of the fittest" and "natural selection". The Darwinian ideas introduced into English society justified a great number of political policies and social movements. England at the turn of the century was still a largest power in the international system. The English perceived, through the justification of Darwinism, they were fit to be the imperial hegemon in the world. The issue this essay will deal with is Imperialism and how Darwinism justified its practice. Darwin argued in his work, The Decent of Man, "When civilised nations come into contact with barbarians the struggle is short except where a deadly climate gives its aid to the native race. . . the grade of civilisation seems to be a most important element in success in competing nations."(Darwin, Decent of Man, p. 297). In this observation, Darwin connotated superiority to civilized nations. In this same work, he referred to the indigenous people as "savages, barbarians and tribal men". This immediately transfers a condescending attitude toward the "uncivilised people". Darwin classified them as tribes while the English and other Aryan cultures were a race. These claims of basic inequality gave the English the "jurisdiction" philosophically, to exploit the colonies to a greater level than previously attained. The drive to "Christianize" the colonies was abandoned, politically. The view shifted from "owing the primitive world" education and Christianity, to a more self-interested "we English are naturally better". Therefore, the we should be exploiting you, because, that is why you are here. Charles Darwin had a tremendous amount of influence on the scientific community and the English population. It can be seen that Darwinism played a large part in justifying the imperial behavior of England. Darwin's studies on nature and the behavior of animals had unlocked "Pandora's Box" in a manner of speaking. He studies reveal how close to nature humanity really is. The English empire quickly saw themselves as a dominant predatorial species of the world. In conclusion, the English empire used Darwinian concept to justify the on-going process of imperialism. Charles Darwin's ideas elevated the ego's of the English people to over-estimate themselves socially and globally. The affects of Darwinism can be seen throughout the spectrum of social interaction both in the animal kingdom and human society.
sábado, 13 de enero de 2007
*The Nature of Science and Biology
THE NATURE OF SCIENCE AND BIOLOGY
Biology: The Science of Our Lives
Biology literally means "the study of life". Biology is such a broad field, covering the minute workings of chemical machines inside our cells, to broad scale concepts of ecosystems and global climate change. Biologists study intimate details of the human brain, the composition of our genes, and even the functioning of our reproductive system. Biologists recently all but completed the deciphering of the human genome, the sequence of deoxyribonucleic acid (DNA) bases that may determine much of our innate capabilities and predispositions to certain forms of behavior and illnesses. DNA sequences have played major roles in criminal cases (O.J. Simpson, as well as the reversal of death penalties for many wrongfully convicted individuals), as well as the impeachment of President Clinton (the stain at least did not lie). We are bombarded with headlines about possible health risks from favorite foods (Chinese, Mexican, hamburgers, etc.) as well as the potential benefits of eating other foods such as cooked tomatoes. Informercials tout the benefits of metabolism-adjusting drugs for weight loss. Many Americans are turning to herbal remedies to ease arthritis pain, improve memory, as well as improve our moods.
Can a biology book give you the answers to these questions? No, but it will enable you learn how to sift through the biases of investigators, the press, and others in a quest to critically evaluate the question. To be honest, five years after you are through with this class it is doubtful you would remember all the details of meatbolism. However, you will know where to look and maybe a little about the process of science that will allow you to make an informed decision. Will you be a scientist? Yes, in a way. You may not be formally trained as a science major, but you can think critically, solve problems, and have some idea about what science can and cannoit do. I hope you will be able to tell the shoe from the shinola.
Science and the Scientific Method
Science is an objective, logical, and repeatable attempt to understand the principles and forces operating in the natural universe. Science is from the Latin word, scientia, to know. Good science is not dogmatic, but should be viewed as an ongoing process of testing and evaluation. One of the hoped-for benefits of students taking a biology course is that they will become more familiar with the process of science.
Humans seem innately interested in the world we live in. Young children drive their parents batty with constant "why" questions. Science is a means to get some of those whys answered. When we shop for groceries, we are conducting a kind of scientific experiment. If you like Brand X of soup, and Brand Y is on sale, perhaps you try Brand Y. If you like it you may buy it again, even when it is not on sale. If you did not like Brand Y, then no sale will get you to try it again.
In order to conduct science, one must know the rules of the game (imagine playing Monopoly and having to discover the rules as you play! Which is precisely what one does with some computer or videogames (before getting the cheatbook). The scientific method is to be used as a guide that can be modified. In some sciences, such as taxonomy and certain types of geology, laboratory experiments are not necessarily performed. Instead, after formulating a hypothesis, additional observations and/or collections are made from different localities.
Steps in the scientific method commonly include:
Observation: defining the problem you wish to explain.
Hypothesis: one or more falsifiable explanations for the observation.
Experimentation: Controlled attempts to test one or more hypotheses.
Conclusion: was the hypothesis supported or not? After this step the hypothesis is either modified or rejected, which causes a repeat of the steps above.
After a hypothesis has been repeatedly tested, a hierarchy of scientific thought develops. Hypothesis is the most common, with the lowest level of certainty. A theory is a hypothesis that has been repeatedly tested with little modification, e.g. The Theory of Evolution. A Law is one of the fundamental underlying principles of how the Universe is organized, e.g. The Laws of Thermodynamics, Newton's Law of Gravity. Science uses the word theory differently than it is used in the general population. Theory to most people, in general nonscientific use, is an untested idea. Scientists call this a hypothesis.
Scientific experiments are also concerned with isolating the variables. A good science experiment does not simultaneously test several variables, but rather a single variable that can be measured against a control. Scientific controlled experiments are situations where all factors are the same between two test subjects, except for the single experimental variable.
Consider a commonly conducted science fair experiment. Sandy wants to test the effect of gangsta rap music on pea plant growth. She plays loud rap music 24 hours a day to a series of pea plants grown under light, and watered every day. At the end of her experiment she concludes gangsta rap is conducive to plant growth. Her teacher grades her project very low, citing the lack of a control group for the experiment. Sandy returns to her experiment, but this time she has a separate group of plants under the same conditions as the rapping plants, but with soothing Led Zeppelin songs playing. She comes to the same conclusion as before, but now has a basis for comparison. Her teacher gives her project a better grade.
Biology: The Science of Our Lives
Biology literally means "the study of life". Biology is such a broad field, covering the minute workings of chemical machines inside our cells, to broad scale concepts of ecosystems and global climate change. Biologists study intimate details of the human brain, the composition of our genes, and even the functioning of our reproductive system. Biologists recently all but completed the deciphering of the human genome, the sequence of deoxyribonucleic acid (DNA) bases that may determine much of our innate capabilities and predispositions to certain forms of behavior and illnesses. DNA sequences have played major roles in criminal cases (O.J. Simpson, as well as the reversal of death penalties for many wrongfully convicted individuals), as well as the impeachment of President Clinton (the stain at least did not lie). We are bombarded with headlines about possible health risks from favorite foods (Chinese, Mexican, hamburgers, etc.) as well as the potential benefits of eating other foods such as cooked tomatoes. Informercials tout the benefits of metabolism-adjusting drugs for weight loss. Many Americans are turning to herbal remedies to ease arthritis pain, improve memory, as well as improve our moods.
Can a biology book give you the answers to these questions? No, but it will enable you learn how to sift through the biases of investigators, the press, and others in a quest to critically evaluate the question. To be honest, five years after you are through with this class it is doubtful you would remember all the details of meatbolism. However, you will know where to look and maybe a little about the process of science that will allow you to make an informed decision. Will you be a scientist? Yes, in a way. You may not be formally trained as a science major, but you can think critically, solve problems, and have some idea about what science can and cannoit do. I hope you will be able to tell the shoe from the shinola.
Science and the Scientific Method
Science is an objective, logical, and repeatable attempt to understand the principles and forces operating in the natural universe. Science is from the Latin word, scientia, to know. Good science is not dogmatic, but should be viewed as an ongoing process of testing and evaluation. One of the hoped-for benefits of students taking a biology course is that they will become more familiar with the process of science.
Humans seem innately interested in the world we live in. Young children drive their parents batty with constant "why" questions. Science is a means to get some of those whys answered. When we shop for groceries, we are conducting a kind of scientific experiment. If you like Brand X of soup, and Brand Y is on sale, perhaps you try Brand Y. If you like it you may buy it again, even when it is not on sale. If you did not like Brand Y, then no sale will get you to try it again.
In order to conduct science, one must know the rules of the game (imagine playing Monopoly and having to discover the rules as you play! Which is precisely what one does with some computer or videogames (before getting the cheatbook). The scientific method is to be used as a guide that can be modified. In some sciences, such as taxonomy and certain types of geology, laboratory experiments are not necessarily performed. Instead, after formulating a hypothesis, additional observations and/or collections are made from different localities.
Steps in the scientific method commonly include:
Observation: defining the problem you wish to explain.
Hypothesis: one or more falsifiable explanations for the observation.
Experimentation: Controlled attempts to test one or more hypotheses.
Conclusion: was the hypothesis supported or not? After this step the hypothesis is either modified or rejected, which causes a repeat of the steps above.
After a hypothesis has been repeatedly tested, a hierarchy of scientific thought develops. Hypothesis is the most common, with the lowest level of certainty. A theory is a hypothesis that has been repeatedly tested with little modification, e.g. The Theory of Evolution. A Law is one of the fundamental underlying principles of how the Universe is organized, e.g. The Laws of Thermodynamics, Newton's Law of Gravity. Science uses the word theory differently than it is used in the general population. Theory to most people, in general nonscientific use, is an untested idea. Scientists call this a hypothesis.
Scientific experiments are also concerned with isolating the variables. A good science experiment does not simultaneously test several variables, but rather a single variable that can be measured against a control. Scientific controlled experiments are situations where all factors are the same between two test subjects, except for the single experimental variable.
Consider a commonly conducted science fair experiment. Sandy wants to test the effect of gangsta rap music on pea plant growth. She plays loud rap music 24 hours a day to a series of pea plants grown under light, and watered every day. At the end of her experiment she concludes gangsta rap is conducive to plant growth. Her teacher grades her project very low, citing the lack of a control group for the experiment. Sandy returns to her experiment, but this time she has a separate group of plants under the same conditions as the rapping plants, but with soothing Led Zeppelin songs playing. She comes to the same conclusion as before, but now has a basis for comparison. Her teacher gives her project a better grade.
7th grade Rain Forest assignment
Life Science 7th Grade
Understanding Animals of the Rain Forest
7th grade needs to articulate everything they already learned last semester.
We will have a corner in our lab dedicated to the: “Amazon Rainforest”.
You need to pick one animal of each class that lives in the amazon rainforest: (fish, amphibian, reptile, bird and mammal).
Describe the animal’s important features, habitat, behaviour, special adaptations, eating habits, circulatory system (notize the evolution of the heart from fish to mammals)
Since we have been studying Human Biology, you will compare all the systems we studied (digestive, respiratory, excretory, nervous and circulatory) with the mammal’s you picked.
In class we will put together all the animals that you studied and you will make presentations for your classmates and some special guests.
This website will help you pick your mammal
http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/index.html
Good luck
Understanding Animals of the Rain Forest
7th grade needs to articulate everything they already learned last semester.
We will have a corner in our lab dedicated to the: “Amazon Rainforest”.
You need to pick one animal of each class that lives in the amazon rainforest: (fish, amphibian, reptile, bird and mammal).
Describe the animal’s important features, habitat, behaviour, special adaptations, eating habits, circulatory system (notize the evolution of the heart from fish to mammals)
Since we have been studying Human Biology, you will compare all the systems we studied (digestive, respiratory, excretory, nervous and circulatory) with the mammal’s you picked.
In class we will put together all the animals that you studied and you will make presentations for your classmates and some special guests.
This website will help you pick your mammal
http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/index.html
Good luck
Mammals on the internet (8th Grade Option B )
8th Grade
"MAMMALS" ON THE INTERNET (option B for 8th grade students who want to work on the internet)
NAME:________________________
FOLLOW DIRECTIONS CAREFULLY!!
ONCE YOUR COMPUTER IS TURNED ON TO THE INTERNET, THEN:
____#1. Go to: http://animaldiversity.ummz.umich.edu
____#2. Under "Shortcuts", click on "Mammals"
#3. Answer the following questions from "Mammalia":
A.The three main characteristics of mammals are:
1. ________________________________________________
2._________________________________________________
3._________________________________________________
B. Mammal hair is made of what?_____________________________
C. Mammals replace teeth only once during their lives. This is called ______________. The first set of teeth are called _____________________
D. Class Mammalia contains ____orders and about _____species.
#4. Move farther down - click on "lnsectivora".
A. Animals of this order feed mainly on _______________
B. Most insectivores are: LARGE or SMALL
C. The sense least used by insectivores is _____________
#5. Click on "Back" or "Mammalia" - then click on "Lagomorpha".
A. These animals are: TERRESTRIAL or AQUATIC
B. Click on family "Leporidae", then click on "eastern cottontail". The classification of the eastern cottontail is:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
C. Are rabbits: CARNIVOROUS or HERBIVOROUS
D. How do rabbits benefit humans? ___________________________________________
#6. Click on "Mammalia" - then click on "Cetacea".
A. Examples of this order are: _____________________________________________
B. Are cetaceans: TERRESTRIAL or AQUATIC
C. Baleen whales feed on ________________________________________________
D. Click on "Delphinidae" - then click on "killer whale" - classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
E. Are killer whales predators? ________
F. Most of the food of the killer whale is_________________and _____________________
G. Are killer whales: SOLITARY or SOCIAL
#7. Click on "Mammalia" - then click on "Artiodactyla".
A. Deer have_____chambers in their stomachs.
B. Click on "Cervidae", this family includes_________, ___________ , and ______________
C. Click on the "whitetail deer" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
D. Whitetail deer feed on _____________________
E. The negative impact that deer have on humans is ______________________________
#8. Click on "Atriodactyla" then click on "Giraffidae".
A. This family has _______ living species, and .
B. Click on the "giraffe" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
#9. Click on "Mammalia" then on "Perissodactyla"
A. This order includes _______________, _____________, and __________________.
B. Click on "Equidae". The first one-toed horse, _______ , lived in the late_____________
C. Click on "Burchell's zebra" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
D. Are Zebras: SOLITARY or SOCIAL.
#10. Of the mammals classified above, _________ and _________ are most closely related.
EXTRA CREDIT
#11. Click on "Mammalia" - then find "Special Topics Contents" and click on that. Then click on "wings" of bats. Do bats have a thumb?
"MAMMALS" ON THE INTERNET (option B for 8th grade students who want to work on the internet)
NAME:________________________
FOLLOW DIRECTIONS CAREFULLY!!
ONCE YOUR COMPUTER IS TURNED ON TO THE INTERNET, THEN:
____#1. Go to: http://animaldiversity.ummz.umich.edu
____#2. Under "Shortcuts", click on "Mammals"
#3. Answer the following questions from "Mammalia":
A.The three main characteristics of mammals are:
1. ________________________________________________
2._________________________________________________
3._________________________________________________
B. Mammal hair is made of what?_____________________________
C. Mammals replace teeth only once during their lives. This is called ______________. The first set of teeth are called _____________________
D. Class Mammalia contains ____orders and about _____species.
#4. Move farther down - click on "lnsectivora".
A. Animals of this order feed mainly on _______________
B. Most insectivores are: LARGE or SMALL
C. The sense least used by insectivores is _____________
#5. Click on "Back" or "Mammalia" - then click on "Lagomorpha".
A. These animals are: TERRESTRIAL or AQUATIC
B. Click on family "Leporidae", then click on "eastern cottontail". The classification of the eastern cottontail is:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
C. Are rabbits: CARNIVOROUS or HERBIVOROUS
D. How do rabbits benefit humans? ___________________________________________
#6. Click on "Mammalia" - then click on "Cetacea".
A. Examples of this order are: _____________________________________________
B. Are cetaceans: TERRESTRIAL or AQUATIC
C. Baleen whales feed on ________________________________________________
D. Click on "Delphinidae" - then click on "killer whale" - classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
E. Are killer whales predators? ________
F. Most of the food of the killer whale is_________________and _____________________
G. Are killer whales: SOLITARY or SOCIAL
#7. Click on "Mammalia" - then click on "Artiodactyla".
A. Deer have_____chambers in their stomachs.
B. Click on "Cervidae", this family includes_________, ___________ , and ______________
C. Click on the "whitetail deer" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
D. Whitetail deer feed on _____________________
E. The negative impact that deer have on humans is ______________________________
#8. Click on "Atriodactyla" then click on "Giraffidae".
A. This family has _______ living species, and .
B. Click on the "giraffe" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
#9. Click on "Mammalia" then on "Perissodactyla"
A. This order includes _______________, _____________, and __________________.
B. Click on "Equidae". The first one-toed horse, _______ , lived in the late_____________
C. Click on "Burchell's zebra" and classify:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
D. Are Zebras: SOLITARY or SOCIAL.
#10. Of the mammals classified above, _________ and _________ are most closely related.
EXTRA CREDIT
#11. Click on "Mammalia" - then find "Special Topics Contents" and click on that. Then click on "wings" of bats. Do bats have a thumb?
HOW TO MAKE FIELD NOTES (8th Grade)
HOW TO MAKE FIELD NOTES
Your objective is to create an accurate written record of your field activities, investigations,
observations and thoughts. You should record date and location information in a
very detailed manner so that others can know exactly when, where, and under what
conditions your work was done. This will enable you or others to return to the same
areas in the future to verify findings and observe changes over time.
GENERAL FORMAT
Follow this format in your field notes:
1. Field notes should be divided into two sections: Journal and Species Accounts
2. Write on one side of the paper. Leave a generous left margin as shown in the examples.
3. Write your name in the upper left-hand corner
4. Write the year in the upper right-hand corner underneath your name.
5. Write the day and month in the upper left margin.
6. Write “Journal” in the top margin of your journal pages, and the name of the species
in the top margin of your species account pages.
7. Write in complete sentences and paragraphs. You can think of field notes as a letter
to a friend or relative explaining what you saw. Or think of them as a letter to someone
visiting the area 20 years later who is unfamiliar with the area.
FOR THE JOURNAL SECTION:
1. Put a heading on the top line of each page which identifies your location. You
should include specific site, city, county and state. Underline the heading. (Joseph
Grinnell underlined his location with a wavy line.)
2. Note the purpose of the trip (Why?)
3. Note who went on the trip with you (Who?).
4. Note the time of day of each important observation (When?).
5. Information about the places you visit should be written so that someone unfamiliar
with the area can find your exact location using maps and your description. Tell where
you started and where you went. Include what road or trail you walked on, or the
general route you took if you did not follow a road. (Where?).
6. Include notes on the weather, elevation, topography, geology, soil, water, vegetation
types, plant phenology (what life stage they are in), and evidence of disturbance (fire,
grazing, cultivation, etc.) (What?).
7. Be accurate. If you have to guess about something, identify your guess as a guess. It
is appropriate to speculate about things and to ask questions. Do include your feelings,
intuitions and thoughts! Just be sure you don’t mislead a reader into thinking your
thoughts are facts!
8. Be detailed and quantify your data as much as possible. “Saw some ducks on the
pond” is not as useful as “saw 12 pintail (7 males and 5 females) on the southeast end
of Olcott Lake about 5 m from the shore.”
9. Sketches and drawings can be very useful. Rough sketches and diagrams add details
and depth to your notes.
10. You may take temporary notes on a smaller field notebook, then transcribe your
notes into your permanent journal. You should transcribe as soon as possible after you
leave the field, and always the same day as your trip.
SPECIES ACCOUNTS
1. Create a page for each species you observe. This is the place for more detailed
descriptions and observations of an individual or group of one particular species.
Include sights, sounds, smells, textures, patterns, sizes, shapes, colors, and movements.
Include numbers of individuals, sizes, frequencies and behaviors.
Your objective is to create an accurate written record of your field activities, investigations,
observations and thoughts. You should record date and location information in a
very detailed manner so that others can know exactly when, where, and under what
conditions your work was done. This will enable you or others to return to the same
areas in the future to verify findings and observe changes over time.
GENERAL FORMAT
Follow this format in your field notes:
1. Field notes should be divided into two sections: Journal and Species Accounts
2. Write on one side of the paper. Leave a generous left margin as shown in the examples.
3. Write your name in the upper left-hand corner
4. Write the year in the upper right-hand corner underneath your name.
5. Write the day and month in the upper left margin.
6. Write “Journal” in the top margin of your journal pages, and the name of the species
in the top margin of your species account pages.
7. Write in complete sentences and paragraphs. You can think of field notes as a letter
to a friend or relative explaining what you saw. Or think of them as a letter to someone
visiting the area 20 years later who is unfamiliar with the area.
FOR THE JOURNAL SECTION:
1. Put a heading on the top line of each page which identifies your location. You
should include specific site, city, county and state. Underline the heading. (Joseph
Grinnell underlined his location with a wavy line.)
2. Note the purpose of the trip (Why?)
3. Note who went on the trip with you (Who?).
4. Note the time of day of each important observation (When?).
5. Information about the places you visit should be written so that someone unfamiliar
with the area can find your exact location using maps and your description. Tell where
you started and where you went. Include what road or trail you walked on, or the
general route you took if you did not follow a road. (Where?).
6. Include notes on the weather, elevation, topography, geology, soil, water, vegetation
types, plant phenology (what life stage they are in), and evidence of disturbance (fire,
grazing, cultivation, etc.) (What?).
7. Be accurate. If you have to guess about something, identify your guess as a guess. It
is appropriate to speculate about things and to ask questions. Do include your feelings,
intuitions and thoughts! Just be sure you don’t mislead a reader into thinking your
thoughts are facts!
8. Be detailed and quantify your data as much as possible. “Saw some ducks on the
pond” is not as useful as “saw 12 pintail (7 males and 5 females) on the southeast end
of Olcott Lake about 5 m from the shore.”
9. Sketches and drawings can be very useful. Rough sketches and diagrams add details
and depth to your notes.
10. You may take temporary notes on a smaller field notebook, then transcribe your
notes into your permanent journal. You should transcribe as soon as possible after you
leave the field, and always the same day as your trip.
SPECIES ACCOUNTS
1. Create a page for each species you observe. This is the place for more detailed
descriptions and observations of an individual or group of one particular species.
Include sights, sounds, smells, textures, patterns, sizes, shapes, colors, and movements.
Include numbers of individuals, sizes, frequencies and behaviors.
Practice how to make field notes (8th grade assignment OPTION A)
Biology 8th Grade (Option A)
Practice your observations
Write Convincing Details
8th graders have begun last year to make field notebooks. This month we will be in charge of filling those field notes.
There are 3 reasons for the class to keep field notes:
1. To learn to make observations outdoors.
2. To help you remember the animals (and other events of natural history) you encounter outside and where you saw them.
3. To document behaviours or study differences among individuals.
Seven Steps to good details
1. Always carry a notebook to write details. Your notebook needs to be small enough to be carried wherever you go. Start every page with the date and time of your observations, a reference of the weather that day is always helpful.
2. Write details immediately. Short-term memory holds specific details for a very short time. Memory may also start to add details that were never seen if left too long.
3. Do drawings and write notes.
4. Describe only what you see. A mistake often made is listing characters of other animals, that are not shared by the observed . Save the elimination of similar species for formal details written later.
5. Don't forget to describe leg colors, bill colors and behavioral details like tail wagging and wing flicking (when you observe a bird).
6. Where possible, call in other observers (family or friends).
7. Write a description from your notes.
If you need more information on how to keep your field notebook (look for HOW TO MAKE FIELD NOTES in the blog's teacher's publications). You will find a more detailed document
Practice your observations
Write Convincing Details
8th graders have begun last year to make field notebooks. This month we will be in charge of filling those field notes.
There are 3 reasons for the class to keep field notes:
1. To learn to make observations outdoors.
2. To help you remember the animals (and other events of natural history) you encounter outside and where you saw them.
3. To document behaviours or study differences among individuals.
Seven Steps to good details
1. Always carry a notebook to write details. Your notebook needs to be small enough to be carried wherever you go. Start every page with the date and time of your observations, a reference of the weather that day is always helpful.
2. Write details immediately. Short-term memory holds specific details for a very short time. Memory may also start to add details that were never seen if left too long.
3. Do drawings and write notes.
4. Describe only what you see. A mistake often made is listing characters of other animals, that are not shared by the observed . Save the elimination of similar species for formal details written later.
5. Don't forget to describe leg colors, bill colors and behavioral details like tail wagging and wing flicking (when you observe a bird).
6. Where possible, call in other observers (family or friends).
7. Write a description from your notes.
If you need more information on how to keep your field notebook (look for HOW TO MAKE FIELD NOTES in the blog's teacher's publications). You will find a more detailed document
A brief History of Life (10th grade assignment)
A Brief History of Life
Biologists studying evolution do a variety of things: population geneticists study the process as it is occurring; systematists seek to determine relationships between species and paleontologists seek to uncover details of the unfolding of life in the past. Discerning these details is often difficult, but hypotheses can be made and tested as new evidence comes to light. This section should be viewed as the best hypothesis scientists have as to the history of the planet. The material here ranges from some issues that are fairly certain to some topics that are nothing more than informed speculation. For some points there are opposing hypotheses -- I have tried to compile a consensus picture. In general, the more remote the time, the more likely the story is incomplete or in error.
Life evolved in the sea. It stayed there for the majority of the history of earth.
The first replicating molecules were most likely RNA. RNA is a nucleic acid similar to DNA. In laboratory studies it has been shown that some RNA sequences have catalytic capabilities. Most importantly, certain RNA sequences act as polymerases -- enzymes that form strands of RNA from its monomers. This process of self replication is the crucial step in the formation of life. This is called the RNA world hypothesis.
The common ancestor of all life probably used RNA as its genetic material. This ancestor gave rise to three major lineages of life. These are: the prokaryotes ("ordinary" bacteria), archaebacteria (thermophilic, methanogenic and halophilic bacteria) and eukaryotes. Eukaryotes include protists (single celled organisms like amoebas and diatoms and a few multicellular forms such as kelp), fungi (including mushrooms and yeast), plants and animals. Eukaryotes and archaebacteria are the two most closely related of the three. The process of translation (making protein from the instructions on a messenger RNA template) is similar in these lineages, but the organization of the genome and transcription (making messenger RNA from a DNA template) is very different in prokaryotes than in eukaryotes and archaebacteria. Scientists interpret this to mean that the common ancestor was RNA based; it gave rise to two lineages that independently formed a DNA genome and hence independently evolved mechanisms to transcribe DNA into RNA.
The first cells must have been anaerobic because there was no oxygen in the atmosphere. In addition, they were probably thermophilic ("heat-loving") and fermentative. Rocks as old as 3.5 billion years old have yielded prokaryotic fossils. Specifically, some rocks from Australia called the Warrawoona series give evidence of bacterial communities organized into structures called stromatolites. Fossils like these have subsequently been found all over the world. These mats of bacteria still form today in a few locales (for example, Shark Bay Australia). Bacteria are the only life forms found in the rocks for a long, long time --eukaryotes (protists) appear about 1.5 billion years ago and fungi-like things appear about 900 million years ago (0.9 billion years ago).
Photosynthesis evolved around 3.4 billion years ago. Photosynthesis is a process that allows organisms to harness sunlight to manufacture sugar from simpler precursors. The first photosystem to evolve, PSI, uses light to convert carbon dioxide (CO2) and hydrogen sulfide (H2S) to glucose. This process releases sulfur as a waste product. About a billion years later, a second photosystem (PS) evolved, probably from a duplication of the first photosystem. Organisms with PSII use both photosystems in conjunction to convert carbon dioxide (CO2) and water (H2O) into glucose. This process releases oxygen as a waste product. Anoxygenic (or H2S) photosynthesis, using PSI, is seen in living purple and green bacteria. Oxygenic (or H2O) photosynthesis, using PSI and PSII, takes place in cyanobacteria. Cyanobacteria are closely related to and hence probably evolved from purple bacterial ancestors. Green bacteria are an outgroup. Since oxygenic bacteria are a lineage within a cluster of anoxygenic lineages, scientists infer that PSI evolved first. This also corroborates with geological evidence.
Green plants and algae also use both photosystems. In these organisms, photosynthesis occurs in organelles (membrane bound structures within the cell) called chloroplasts. These organelles originated as free living bacteria related to the cyanobacteria that were engulfed by ur-eukaryotes and eventually entered into an endosymbiotic relationship. This endosymbiotic theory of eukaryotic organelles was championed by Lynn Margulis. Originally controversial, this theory is now accepted. One key line of evidence in support of this idea came when the DNA inside chloroplasts was sequenced -- the gene sequences were more similar to free-living cyanobacteria sequences than to sequences from the plants the chloroplasts resided in.
After the advent of photosystem II, oxygen levels increased. Dissolved oxygen in the oceans increased as well as atmospheric oxygen. This is sometimes called the oxygen holocaust. Oxygen is a very good electron acceptor and can be very damaging to living organisms. Many bacteria are anaerobic and die almost immediately in the presence of oxygen. Other organisms, like animals, have special ways to avoid cellular damage due to this element (and in fact require it to live.) Initially, when oxygen began building up in the environment, it was neutralized by materials already present. Iron, which existed in high concentrations in the sea was oxidized and precipitated. Evidence of this can be seen in banded iron formations from this time, layers of iron deposited on the sea floor. As one geologist put it, "the world rusted." Eventually, it grew to high enough concentrations to be dangerous to living things. In response, many species went extinct, some continued (and still continue) to thrive in anaerobic microenvironments and several lineages independently evolved oxygen respiration.
The purple bacteria evolved oxygen respiration by reversing the flow of molecules through their carbon fixing pathways and modifying their electron transport chains. Purple bacteria also enabled the eukaryotic lineage to become aerobic. Eukaryotic cells have membrane bound organelles called mitochondria that take care of respiration for the cell. These are endosymbionts like chloroplasts. Mitochondria formed this symbiotic relationship very early in eukaryotic history, all but a few groups of eukaryotic cells have mitochondria. Later, a few lineages picked up chloroplasts. Chloroplasts have multiple origins. Red algae picked up ur-chloroplasts from the cyanobacterial lineage. Green algae, the group plants evolved from, picked up different urchloroplasts from a prochlorophyte, a lineage closely related to cyanobacteria.
Animals start appearing prior to the Cambrian, about 600 million years ago. The first animals dating from just before the Cambrian were found in rocks near Adelaide, Australia. They are called the Ediacarian fauna and have subsequently been found in other locales as well. It is unclear if these forms have any surviving descendants. Some look a bit like Cnidarians (jellyfish, sea anemones and the like); others resemble annelids (earthworms). All the phyla (the second highest taxonomic category) of animals appeared around the Cambrian. The Cambrian 'explosion' may have been a result of higher oxygen concentrations enabling larger organisms with higher metabolisms to evolve. Or it might be due to the spreading of shallow seas at that time providing a variety of new niches. In any case, the radiation produced a wide variety of animals.
Some paleontologists think more animal phyla were present then than now. The animals of the Burgess shale are an example of Cambrian animal fossils. These fossils, from Canada, show a bizarre array of creatures, some which appear to have unique body plans unlike those seen in any living animals.
The extent of the Cambrian explosion is often overstated. Although quick, the Cambrian explosion is not instantaneous in geologic time. Also, there is evidence of animal life prior to the Cambrian. In addition, although all the phyla of animals came into being, these were not the modern forms we see today. Our own phylum (which we share with other mammals, reptiles, birds, amphibians and fish) was represented by a small, sliver-like thing called Pikaia. Plants were not yet present. Photosynthetic protists and algae were the bottom of the food chain. Following the Cambrian, the number of marine families leveled off at a little less than 200.
The Ordovician explosion, around 500 million years ago, followed. This 'explosion', larger than the Cambrian, introduced numerous families of the Paleozoic fauna (including crinoids, articulate brachiopods, cephalopods and corals). The Cambrian fauna, (trilobites, inarticulate brachiopods, etc.) declined slowly during this time. By the end of the Ordovician, the Cambrian fauna had mostly given way to the Paleozoic fauna and the number of marine families was just over 400. It stayed at this level until the end of the Permian period.
Plants evolved from ancient green algae over 400 million years ago. Both groups use chlorophyll a and b as photosynthetic pigments. In addition, plants and green algae are the only groups to store starch in their chloroplasts. Plants and fungi (in symbiosis) invaded the land about 400 million years ago. The first plants were moss-like and required moist environments to survive. Later, evolutionary developments such as a waxy cuticle allowed some plants to exploit more inland environments. Still mosses lack true vascular tissue to transport fluids and nutrients. This limits their size since these must diffuse through the plant. Vascular plants evolved from mosses. The first vascular land plant known is Cooksonia, a spiky, branching, leafless structure. At the same time, or shortly thereafter, arthropods followed plants onto the land. The first land animals known are myriapods -- centipedes and millipedes.
Vertebrates moved onto the land by the Devonian period, about 380 million years ago. Ichthyostega, an amphibian, is the among the first known land vertebrates. It was found in Greenland and was derived from lobe-finned fishes called Rhipidistians. Amphibians gave rise to reptiles. Reptiles had evolved scales to decrease water loss and a shelled egg permitting young to be hatched on land. Among the earliest well preserved reptiles is Hylonomus, from rocks in Nova Scotia.
The Permian extinction was the largest extinction in history. It happened about 250 million years ago. The last of the Cambrian Fauna went extinct. The Paleozoic fauna took a nose dive from about 300 families to about 50. It is estimated that 96% of all species (50% of all Families) met their end. Following this event, the Modern fauna, which had been slowly expanding since the Ordovician, took over.
The Modern fauna includes fish, bivalves, gastropods and crabs. These were barely affected by the Permian extinction. The Modern fauna subsequently increased to over 600 marine families at present. The Paleozoic fauna held steady at about 100 families. A second extinction event shortly following the Permian kept animal diversity low for awhile.
During the Carboniferous (the period just prior to the Permian) and in the Permian the landscape was dominated by ferns and their relatives. After the Permian extinction, gymnosperms (ex. pines) became more abundant. Gymnosperms had evolved seeds, from seedless fern ancestors, which helped their ability to disperse. Gymnosperms also evolved pollen, encased sperm which allowed for more outcrossing.
Dinosaurs evolved from archosaur reptiles, their closest living relatives are crocodiles. One modification that may have been a key to their success was the evolution of an upright stance. Amphibians and reptiles have a splayed stance and walk with an undulating pattern because their limbs are modified from fins. Their gait is modified from the swimming movement of fish. Splay stanced animals cannot sustain continued locomotion because they cannot breathe while they move; their undulating movement compresses their chest cavity. Thus, they must stop every few steps and breath before continuing on their way. Dinosaurs evolved an upright stance similar to the upright stance mammals independently evolved. This allowed for continual locomotion. In addition, dinosaurs evolved to be warm-blooded. Warmbloodedness allows an increase in the vigor of movements in erect organisms. Splay stanced organisms would probably not benefit from warm- bloodedness. Birds evolved from sauriscian dinosaurs. Cladistically, birds are dinosaurs. The transitional fossil Archaeopteryx has a mixture of reptilian and avian features.
Angiosperms evolved from gymnosperms, their closest relatives are Gnetae. Two key adaptations allowed them to displace gymnosperms as the dominant fauna -- fruits and flowers. Fruits (modified plant ovaries) allow for animal-based seed dispersal and deposition with plenty of fertilizer. Flowers evolved to facilitate animal, especially insect, based pollen dispersal. Petals are modified leaves. Angiosperms currently dominate the flora of the world -- over three fourths of all living plants are angiosperms.
Insects evolved from primitive segmented arthropods. The mouth parts of insects are modified legs. Insects are closely related to annelids. Insects dominate the fauna of the world. Over half of all named species are insects. One third of this number are beetles.
The end of the Cretaceous, about 65 million years ago, is marked by a minor mass extinction. This extinction marked the demise of all the lineages of dinosaurs save the birds. Up to this point mammals were confined to nocturnal, insectivorous niches. Once the dinosaurs were out of the picture, they diversified. Morgonucudon , a contemporary of dinosaurs, is an example of one of the first mammals. Mammals evolved from therapsid reptiles. The finback reptile Diametrodon is an example of a therapsid. One of the most successful lineages of mammals is, of course, humans. Humans are neotenous apes. Neoteny is a process which leads to an organism reaching reproductive capacity in its juvenile form. The primary line of evidence for this is the similarities between young apes and adult humans. Louis Bolk compiled a list of 25 features shared between adult humans and juvenile apes, including facial morphology, high relative brain weight, absence of brow ridges and cranial crests.
The earth has been in a state of flux for 4 billion years. Across this time, the abundance of different lineages varies wildly. New lineages evolve and radiate out across the face of the planet, pushing older lineages to extinction, or relictual existence in protected refugia or suitable microhabitats. Organisms modify their environments. This can be disastrous, as in the case of the oxygen holocaust. However, environmental modification can be the impetus for further evolutionary change. Overall, diversity has increased since the beginning of life. This increase is, however, interrupted numerous times by mass extinctions. Diversity appears to have hit an all-time high just prior to the appearance of humans. As the human population has increased, biological diversity has decreased at an ever-increasing pace. The correlation is probably causal.
Q&A.
1. List and describe 10 areas of study in Biology. (Ex: evolutionary biology)
2. Describe the celluar differences between the prokaryotes ("ordinary" bacteria), archaebacteria (thermophilic, methanogenic and halophilic bacteria) and eukaryotes. Eukaryotes include protists (single celled organisms like amoebas and others).
3. Where do scientists believe life originated?
4. Modern biology is based on several great ideas, or theories: The Cell Theory, Theory of Evolution by Natural Selection, Gene Theory, Homeostasis. Write the main statements that each of these theories hold.
5. Explain the importance of photosynthesis in nature.
6. What events happened during the “Cambrian explosion”?
7. Why do scientists believe flowering plants evolved?
8. What are endosymbionts? What organelles in modern cells are believed to have evolved from endosymbiontic organisms?
9. When did the first animals appear on Earth?
10. Contrast Creationism and Evolution. Write a short essay explaining both points of view; state your personal opinions (conclusions) and the reasons why you came to that conclusion.
Biologists studying evolution do a variety of things: population geneticists study the process as it is occurring; systematists seek to determine relationships between species and paleontologists seek to uncover details of the unfolding of life in the past. Discerning these details is often difficult, but hypotheses can be made and tested as new evidence comes to light. This section should be viewed as the best hypothesis scientists have as to the history of the planet. The material here ranges from some issues that are fairly certain to some topics that are nothing more than informed speculation. For some points there are opposing hypotheses -- I have tried to compile a consensus picture. In general, the more remote the time, the more likely the story is incomplete or in error.
Life evolved in the sea. It stayed there for the majority of the history of earth.
The first replicating molecules were most likely RNA. RNA is a nucleic acid similar to DNA. In laboratory studies it has been shown that some RNA sequences have catalytic capabilities. Most importantly, certain RNA sequences act as polymerases -- enzymes that form strands of RNA from its monomers. This process of self replication is the crucial step in the formation of life. This is called the RNA world hypothesis.
The common ancestor of all life probably used RNA as its genetic material. This ancestor gave rise to three major lineages of life. These are: the prokaryotes ("ordinary" bacteria), archaebacteria (thermophilic, methanogenic and halophilic bacteria) and eukaryotes. Eukaryotes include protists (single celled organisms like amoebas and diatoms and a few multicellular forms such as kelp), fungi (including mushrooms and yeast), plants and animals. Eukaryotes and archaebacteria are the two most closely related of the three. The process of translation (making protein from the instructions on a messenger RNA template) is similar in these lineages, but the organization of the genome and transcription (making messenger RNA from a DNA template) is very different in prokaryotes than in eukaryotes and archaebacteria. Scientists interpret this to mean that the common ancestor was RNA based; it gave rise to two lineages that independently formed a DNA genome and hence independently evolved mechanisms to transcribe DNA into RNA.
The first cells must have been anaerobic because there was no oxygen in the atmosphere. In addition, they were probably thermophilic ("heat-loving") and fermentative. Rocks as old as 3.5 billion years old have yielded prokaryotic fossils. Specifically, some rocks from Australia called the Warrawoona series give evidence of bacterial communities organized into structures called stromatolites. Fossils like these have subsequently been found all over the world. These mats of bacteria still form today in a few locales (for example, Shark Bay Australia). Bacteria are the only life forms found in the rocks for a long, long time --eukaryotes (protists) appear about 1.5 billion years ago and fungi-like things appear about 900 million years ago (0.9 billion years ago).
Photosynthesis evolved around 3.4 billion years ago. Photosynthesis is a process that allows organisms to harness sunlight to manufacture sugar from simpler precursors. The first photosystem to evolve, PSI, uses light to convert carbon dioxide (CO2) and hydrogen sulfide (H2S) to glucose. This process releases sulfur as a waste product. About a billion years later, a second photosystem (PS) evolved, probably from a duplication of the first photosystem. Organisms with PSII use both photosystems in conjunction to convert carbon dioxide (CO2) and water (H2O) into glucose. This process releases oxygen as a waste product. Anoxygenic (or H2S) photosynthesis, using PSI, is seen in living purple and green bacteria. Oxygenic (or H2O) photosynthesis, using PSI and PSII, takes place in cyanobacteria. Cyanobacteria are closely related to and hence probably evolved from purple bacterial ancestors. Green bacteria are an outgroup. Since oxygenic bacteria are a lineage within a cluster of anoxygenic lineages, scientists infer that PSI evolved first. This also corroborates with geological evidence.
Green plants and algae also use both photosystems. In these organisms, photosynthesis occurs in organelles (membrane bound structures within the cell) called chloroplasts. These organelles originated as free living bacteria related to the cyanobacteria that were engulfed by ur-eukaryotes and eventually entered into an endosymbiotic relationship. This endosymbiotic theory of eukaryotic organelles was championed by Lynn Margulis. Originally controversial, this theory is now accepted. One key line of evidence in support of this idea came when the DNA inside chloroplasts was sequenced -- the gene sequences were more similar to free-living cyanobacteria sequences than to sequences from the plants the chloroplasts resided in.
After the advent of photosystem II, oxygen levels increased. Dissolved oxygen in the oceans increased as well as atmospheric oxygen. This is sometimes called the oxygen holocaust. Oxygen is a very good electron acceptor and can be very damaging to living organisms. Many bacteria are anaerobic and die almost immediately in the presence of oxygen. Other organisms, like animals, have special ways to avoid cellular damage due to this element (and in fact require it to live.) Initially, when oxygen began building up in the environment, it was neutralized by materials already present. Iron, which existed in high concentrations in the sea was oxidized and precipitated. Evidence of this can be seen in banded iron formations from this time, layers of iron deposited on the sea floor. As one geologist put it, "the world rusted." Eventually, it grew to high enough concentrations to be dangerous to living things. In response, many species went extinct, some continued (and still continue) to thrive in anaerobic microenvironments and several lineages independently evolved oxygen respiration.
The purple bacteria evolved oxygen respiration by reversing the flow of molecules through their carbon fixing pathways and modifying their electron transport chains. Purple bacteria also enabled the eukaryotic lineage to become aerobic. Eukaryotic cells have membrane bound organelles called mitochondria that take care of respiration for the cell. These are endosymbionts like chloroplasts. Mitochondria formed this symbiotic relationship very early in eukaryotic history, all but a few groups of eukaryotic cells have mitochondria. Later, a few lineages picked up chloroplasts. Chloroplasts have multiple origins. Red algae picked up ur-chloroplasts from the cyanobacterial lineage. Green algae, the group plants evolved from, picked up different urchloroplasts from a prochlorophyte, a lineage closely related to cyanobacteria.
Animals start appearing prior to the Cambrian, about 600 million years ago. The first animals dating from just before the Cambrian were found in rocks near Adelaide, Australia. They are called the Ediacarian fauna and have subsequently been found in other locales as well. It is unclear if these forms have any surviving descendants. Some look a bit like Cnidarians (jellyfish, sea anemones and the like); others resemble annelids (earthworms). All the phyla (the second highest taxonomic category) of animals appeared around the Cambrian. The Cambrian 'explosion' may have been a result of higher oxygen concentrations enabling larger organisms with higher metabolisms to evolve. Or it might be due to the spreading of shallow seas at that time providing a variety of new niches. In any case, the radiation produced a wide variety of animals.
Some paleontologists think more animal phyla were present then than now. The animals of the Burgess shale are an example of Cambrian animal fossils. These fossils, from Canada, show a bizarre array of creatures, some which appear to have unique body plans unlike those seen in any living animals.
The extent of the Cambrian explosion is often overstated. Although quick, the Cambrian explosion is not instantaneous in geologic time. Also, there is evidence of animal life prior to the Cambrian. In addition, although all the phyla of animals came into being, these were not the modern forms we see today. Our own phylum (which we share with other mammals, reptiles, birds, amphibians and fish) was represented by a small, sliver-like thing called Pikaia. Plants were not yet present. Photosynthetic protists and algae were the bottom of the food chain. Following the Cambrian, the number of marine families leveled off at a little less than 200.
The Ordovician explosion, around 500 million years ago, followed. This 'explosion', larger than the Cambrian, introduced numerous families of the Paleozoic fauna (including crinoids, articulate brachiopods, cephalopods and corals). The Cambrian fauna, (trilobites, inarticulate brachiopods, etc.) declined slowly during this time. By the end of the Ordovician, the Cambrian fauna had mostly given way to the Paleozoic fauna and the number of marine families was just over 400. It stayed at this level until the end of the Permian period.
Plants evolved from ancient green algae over 400 million years ago. Both groups use chlorophyll a and b as photosynthetic pigments. In addition, plants and green algae are the only groups to store starch in their chloroplasts. Plants and fungi (in symbiosis) invaded the land about 400 million years ago. The first plants were moss-like and required moist environments to survive. Later, evolutionary developments such as a waxy cuticle allowed some plants to exploit more inland environments. Still mosses lack true vascular tissue to transport fluids and nutrients. This limits their size since these must diffuse through the plant. Vascular plants evolved from mosses. The first vascular land plant known is Cooksonia, a spiky, branching, leafless structure. At the same time, or shortly thereafter, arthropods followed plants onto the land. The first land animals known are myriapods -- centipedes and millipedes.
Vertebrates moved onto the land by the Devonian period, about 380 million years ago. Ichthyostega, an amphibian, is the among the first known land vertebrates. It was found in Greenland and was derived from lobe-finned fishes called Rhipidistians. Amphibians gave rise to reptiles. Reptiles had evolved scales to decrease water loss and a shelled egg permitting young to be hatched on land. Among the earliest well preserved reptiles is Hylonomus, from rocks in Nova Scotia.
The Permian extinction was the largest extinction in history. It happened about 250 million years ago. The last of the Cambrian Fauna went extinct. The Paleozoic fauna took a nose dive from about 300 families to about 50. It is estimated that 96% of all species (50% of all Families) met their end. Following this event, the Modern fauna, which had been slowly expanding since the Ordovician, took over.
The Modern fauna includes fish, bivalves, gastropods and crabs. These were barely affected by the Permian extinction. The Modern fauna subsequently increased to over 600 marine families at present. The Paleozoic fauna held steady at about 100 families. A second extinction event shortly following the Permian kept animal diversity low for awhile.
During the Carboniferous (the period just prior to the Permian) and in the Permian the landscape was dominated by ferns and their relatives. After the Permian extinction, gymnosperms (ex. pines) became more abundant. Gymnosperms had evolved seeds, from seedless fern ancestors, which helped their ability to disperse. Gymnosperms also evolved pollen, encased sperm which allowed for more outcrossing.
Dinosaurs evolved from archosaur reptiles, their closest living relatives are crocodiles. One modification that may have been a key to their success was the evolution of an upright stance. Amphibians and reptiles have a splayed stance and walk with an undulating pattern because their limbs are modified from fins. Their gait is modified from the swimming movement of fish. Splay stanced animals cannot sustain continued locomotion because they cannot breathe while they move; their undulating movement compresses their chest cavity. Thus, they must stop every few steps and breath before continuing on their way. Dinosaurs evolved an upright stance similar to the upright stance mammals independently evolved. This allowed for continual locomotion. In addition, dinosaurs evolved to be warm-blooded. Warmbloodedness allows an increase in the vigor of movements in erect organisms. Splay stanced organisms would probably not benefit from warm- bloodedness. Birds evolved from sauriscian dinosaurs. Cladistically, birds are dinosaurs. The transitional fossil Archaeopteryx has a mixture of reptilian and avian features.
Angiosperms evolved from gymnosperms, their closest relatives are Gnetae. Two key adaptations allowed them to displace gymnosperms as the dominant fauna -- fruits and flowers. Fruits (modified plant ovaries) allow for animal-based seed dispersal and deposition with plenty of fertilizer. Flowers evolved to facilitate animal, especially insect, based pollen dispersal. Petals are modified leaves. Angiosperms currently dominate the flora of the world -- over three fourths of all living plants are angiosperms.
Insects evolved from primitive segmented arthropods. The mouth parts of insects are modified legs. Insects are closely related to annelids. Insects dominate the fauna of the world. Over half of all named species are insects. One third of this number are beetles.
The end of the Cretaceous, about 65 million years ago, is marked by a minor mass extinction. This extinction marked the demise of all the lineages of dinosaurs save the birds. Up to this point mammals were confined to nocturnal, insectivorous niches. Once the dinosaurs were out of the picture, they diversified. Morgonucudon , a contemporary of dinosaurs, is an example of one of the first mammals. Mammals evolved from therapsid reptiles. The finback reptile Diametrodon is an example of a therapsid. One of the most successful lineages of mammals is, of course, humans. Humans are neotenous apes. Neoteny is a process which leads to an organism reaching reproductive capacity in its juvenile form. The primary line of evidence for this is the similarities between young apes and adult humans. Louis Bolk compiled a list of 25 features shared between adult humans and juvenile apes, including facial morphology, high relative brain weight, absence of brow ridges and cranial crests.
The earth has been in a state of flux for 4 billion years. Across this time, the abundance of different lineages varies wildly. New lineages evolve and radiate out across the face of the planet, pushing older lineages to extinction, or relictual existence in protected refugia or suitable microhabitats. Organisms modify their environments. This can be disastrous, as in the case of the oxygen holocaust. However, environmental modification can be the impetus for further evolutionary change. Overall, diversity has increased since the beginning of life. This increase is, however, interrupted numerous times by mass extinctions. Diversity appears to have hit an all-time high just prior to the appearance of humans. As the human population has increased, biological diversity has decreased at an ever-increasing pace. The correlation is probably causal.
Q&A.
1. List and describe 10 areas of study in Biology. (Ex: evolutionary biology)
2. Describe the celluar differences between the prokaryotes ("ordinary" bacteria), archaebacteria (thermophilic, methanogenic and halophilic bacteria) and eukaryotes. Eukaryotes include protists (single celled organisms like amoebas and others).
3. Where do scientists believe life originated?
4. Modern biology is based on several great ideas, or theories: The Cell Theory, Theory of Evolution by Natural Selection, Gene Theory, Homeostasis. Write the main statements that each of these theories hold.
5. Explain the importance of photosynthesis in nature.
6. What events happened during the “Cambrian explosion”?
7. Why do scientists believe flowering plants evolved?
8. What are endosymbionts? What organelles in modern cells are believed to have evolved from endosymbiontic organisms?
9. When did the first animals appear on Earth?
10. Contrast Creationism and Evolution. Write a short essay explaining both points of view; state your personal opinions (conclusions) and the reasons why you came to that conclusion.
viernes, 12 de enero de 2007
*EVOLUTION (Anatomy and Embryology)
Comparative Anatomy and Embryology
The biochemical universals are the most impressive and the most recently discovered, but certainly they are not the only vestiges of creation by means of evolution. Comparative anatomy and embryology proclaim the evolutionary origins of the present inhabitants of the world. In 1555 Pierre Belon established the presence of homologous bones in the superficially very different skeletons of man and bird. Later anatomists traced the homologies in the skeletons, as well as in other organs, of all vertebrates. Homologies are also traceable in the external skeletons of arthropods as seemingly unlike as a lobster, a fly, and a butterfly. Examples of homologies can be multiplied indefinitely. Embryos of apparently quite diverse animals often exhibit striking similarities. A century ago these similarities led some biologists (notably the German zoologist Ernst Haeckel) to be carried by their enthusiasm as far as to interpret the embryonic similarities as meaning that the embryo repeats in its development the evolutionary history of its species: it was said to pass through stages in which it resembles its remote ancestors. In other words, early-day biologists supposed that by studying embryonic development one can, as it were, read off the stages through which the evolutionary development had passed. This so-called biogenetic law is no longer credited in its original form. And yet embryonic similarities are undeniable impressive and significant. Probably everybody knows the sedentary barnacles which seem to have no similarity to free-swimming crustaceans, such as the copepods. How remarkable that barnacles pass through a free-swimming larval stage, the nauplius! At that stage of its development a barnacle and a Cyclops look unmistakably similar. They are evidently relatives. The presence of gill slits in human embryos and in embryos of other terrestrial vertebrates is another famous example. Of course, at no stage of its development is a human embryo a fish, nor does it ever have functioning gills. But why should it have unmistakable gill slits unless its remote ancestors did respire with the aid of gills? It is the Creator again playing practical jokes? Adaptive radiation: Hawaii’s Flies There are about 2,000 species of drosophilid flies in the world as a whole. About a quarter of them occur in Hawaii, although the total area of the archipelago is only about that of the state of New Jersey. All but 17 of the species in Hawaii are endemic (found nowhere else). Furthermore, a great majority of the Hawaiian endemics do not occur throughout the archipelago: they are restricted to single islands or even to a part of an island. What is the explanation of this extraordinary proliferation of drosophilid species in so small a territory? Recent work of H. L. Carson, H. T. Spieth, D. E. Hardy, and others makes the situation understandable. The Hawaiian Islands are of volcanic origin; they were never parts of any continent. Their ages are between 5.6 and 0.7 million years. Before man came there inhabitants were descendants of immigrants that had been transported across the ocean by air currents and other accidental means. A single drosophilid species, which arrived in Hawaii first, before there were numerous competitors, faced the challenge of an abundance of many unoccupied ecologic niches. Its descendants responded to this challenge by evolutionary adaptive radiation, the products of which are the remarkable Hawaiian drosophilids of today. To forestall a possible misunderstanding, let it be made clear that the Hawaiian endemics are by no means so similar to each other that they could be mistaken for variants of the same species; if anything, they are more diversified than are drosophilids elsewhere. The largest and the smallest drosophilid species are both Hawaiian. They exhibit an astonishing variety of behavior patterns. Some of them have become adapted to ways of life quite extraordinary for a drosophilid fly, such as being parasites in egg cocoons of spiders. Oceanic islands other than Hawaii, scattered over the wide Pacific Ocean, are not conspicuously rich in endemic species of drosophilids. The most probable explanation of this fact is that these other islands were colonized by drosophilid after most ecologic niches had already been filled by earlier arrivals. This surely is a hypothesis, but it is a reasonable one. Antievolutionists might perhaps suggest an alternative hypothesis: in a fit of absentmindedness, the Creator went on manufacturing more and more drosophilid species for Hawaii, until there was an extravagant surfeit of them in this archipelago. I leave it up to you to decide which hypothesis makes sense. Strength and Acceptance of the Theory Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts some of them interesting or curious but making no meaningful picture as a whole. This is not to imply that we know everything that can and should be known about biology and about evolution. Any competent biologist is aware of a multitude of problems yet unresolved and of questions yet unanswered. After all, biologic research shows no sign of approaching completion; quite the opposite is true. Disagreements and clashes of opinion are rife among biologists, as they should be in a living and growing science. Antievolutionists mistake, or pretend to mistake, these disagreements as indications of dubiousness of the entire doctrine of evolution. Their favorite sport is stringing together quotations, carefully and sometimes expertly taken out of context, to show that nothing is really established or agreed upon among evolutionists. Some of my colleagues and myself have been amused and amazed to read ourselves quoted in a way showing that we are really antievolutionists under the skin. Let me try to make crystal clear what is established beyond reasonable doubt, and what needs further study, about evolution. Evolution as a process that has always gone on in the history of the earth can be doubted only by those who are ignorant of the evidence or are resistant to evidence, owing to emotional blocks or to plain bigotry. By contrast, the mechanisms that bring evolution about certainly need study and clarification. There are no alternatives to evolution as history that can withstand critical examination. Yet we are constantly learning new and important facts about evolutionary mechanisms. It is remarkable that more than a century ago Darwin was able to discern so much about evolution without having available to him the key facts discovered since. The development of genetics after 1900 especially of molecular genetics, in the last two decades has provided information essential to the understanding of evolutionary mechanisms. But much is in doubt and much remains to be learned. This is heartening and inspiring for any scientist worth his salt. Imagine that everything is completely known and that science has nothing more to discover: what a nightmare! Does the evolutionary doctrine clash with religious faith? It does not. It is a blunder to mistake the Holy Scriptures for elementary textbooks of astronomy, geology, biology, and anthropology. Only if symbols are construed to mean what they are not intended to mean can there arise imaginary, insoluble conflicts. As pointed out above, the blunder leads to blasphemy: the Creator is accused of systematic deceitfulness. One of the great thinkers of our age, Pierre Teilhard de Chardin, wrote the following: "Is evolution a theory, a system, or a hypothesis? It is much more it is a general postulate to which all theories, all hypotheses, all systems much henceforward bow and which they must satisfy in order to be thinkable and true. Evolution is a light which illuminates all facts, a trajectory which all lines of though must follow this is what evolution is." Of course, some scientists, as well as some philosophers and theologians, disagree with some parts of Teilhard’s teachings; the acceptance of his worldview falls short of universal. But there is no doubt at all that Teilhard was a truly and deeply religious man and that Christianity was the cornerstone of his worldview. Moreover, in his worldview science and faith were not segregated in watertight compartments, as they are with so many people. They were harmoniously fitting parts of his worldview. Teilhard was a creationist, but one who understood that the Creation is realized in this world by means of evolution.
The biochemical universals are the most impressive and the most recently discovered, but certainly they are not the only vestiges of creation by means of evolution. Comparative anatomy and embryology proclaim the evolutionary origins of the present inhabitants of the world. In 1555 Pierre Belon established the presence of homologous bones in the superficially very different skeletons of man and bird. Later anatomists traced the homologies in the skeletons, as well as in other organs, of all vertebrates. Homologies are also traceable in the external skeletons of arthropods as seemingly unlike as a lobster, a fly, and a butterfly. Examples of homologies can be multiplied indefinitely. Embryos of apparently quite diverse animals often exhibit striking similarities. A century ago these similarities led some biologists (notably the German zoologist Ernst Haeckel) to be carried by their enthusiasm as far as to interpret the embryonic similarities as meaning that the embryo repeats in its development the evolutionary history of its species: it was said to pass through stages in which it resembles its remote ancestors. In other words, early-day biologists supposed that by studying embryonic development one can, as it were, read off the stages through which the evolutionary development had passed. This so-called biogenetic law is no longer credited in its original form. And yet embryonic similarities are undeniable impressive and significant. Probably everybody knows the sedentary barnacles which seem to have no similarity to free-swimming crustaceans, such as the copepods. How remarkable that barnacles pass through a free-swimming larval stage, the nauplius! At that stage of its development a barnacle and a Cyclops look unmistakably similar. They are evidently relatives. The presence of gill slits in human embryos and in embryos of other terrestrial vertebrates is another famous example. Of course, at no stage of its development is a human embryo a fish, nor does it ever have functioning gills. But why should it have unmistakable gill slits unless its remote ancestors did respire with the aid of gills? It is the Creator again playing practical jokes? Adaptive radiation: Hawaii’s Flies There are about 2,000 species of drosophilid flies in the world as a whole. About a quarter of them occur in Hawaii, although the total area of the archipelago is only about that of the state of New Jersey. All but 17 of the species in Hawaii are endemic (found nowhere else). Furthermore, a great majority of the Hawaiian endemics do not occur throughout the archipelago: they are restricted to single islands or even to a part of an island. What is the explanation of this extraordinary proliferation of drosophilid species in so small a territory? Recent work of H. L. Carson, H. T. Spieth, D. E. Hardy, and others makes the situation understandable. The Hawaiian Islands are of volcanic origin; they were never parts of any continent. Their ages are between 5.6 and 0.7 million years. Before man came there inhabitants were descendants of immigrants that had been transported across the ocean by air currents and other accidental means. A single drosophilid species, which arrived in Hawaii first, before there were numerous competitors, faced the challenge of an abundance of many unoccupied ecologic niches. Its descendants responded to this challenge by evolutionary adaptive radiation, the products of which are the remarkable Hawaiian drosophilids of today. To forestall a possible misunderstanding, let it be made clear that the Hawaiian endemics are by no means so similar to each other that they could be mistaken for variants of the same species; if anything, they are more diversified than are drosophilids elsewhere. The largest and the smallest drosophilid species are both Hawaiian. They exhibit an astonishing variety of behavior patterns. Some of them have become adapted to ways of life quite extraordinary for a drosophilid fly, such as being parasites in egg cocoons of spiders. Oceanic islands other than Hawaii, scattered over the wide Pacific Ocean, are not conspicuously rich in endemic species of drosophilids. The most probable explanation of this fact is that these other islands were colonized by drosophilid after most ecologic niches had already been filled by earlier arrivals. This surely is a hypothesis, but it is a reasonable one. Antievolutionists might perhaps suggest an alternative hypothesis: in a fit of absentmindedness, the Creator went on manufacturing more and more drosophilid species for Hawaii, until there was an extravagant surfeit of them in this archipelago. I leave it up to you to decide which hypothesis makes sense. Strength and Acceptance of the Theory Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts some of them interesting or curious but making no meaningful picture as a whole. This is not to imply that we know everything that can and should be known about biology and about evolution. Any competent biologist is aware of a multitude of problems yet unresolved and of questions yet unanswered. After all, biologic research shows no sign of approaching completion; quite the opposite is true. Disagreements and clashes of opinion are rife among biologists, as they should be in a living and growing science. Antievolutionists mistake, or pretend to mistake, these disagreements as indications of dubiousness of the entire doctrine of evolution. Their favorite sport is stringing together quotations, carefully and sometimes expertly taken out of context, to show that nothing is really established or agreed upon among evolutionists. Some of my colleagues and myself have been amused and amazed to read ourselves quoted in a way showing that we are really antievolutionists under the skin. Let me try to make crystal clear what is established beyond reasonable doubt, and what needs further study, about evolution. Evolution as a process that has always gone on in the history of the earth can be doubted only by those who are ignorant of the evidence or are resistant to evidence, owing to emotional blocks or to plain bigotry. By contrast, the mechanisms that bring evolution about certainly need study and clarification. There are no alternatives to evolution as history that can withstand critical examination. Yet we are constantly learning new and important facts about evolutionary mechanisms. It is remarkable that more than a century ago Darwin was able to discern so much about evolution without having available to him the key facts discovered since. The development of genetics after 1900 especially of molecular genetics, in the last two decades has provided information essential to the understanding of evolutionary mechanisms. But much is in doubt and much remains to be learned. This is heartening and inspiring for any scientist worth his salt. Imagine that everything is completely known and that science has nothing more to discover: what a nightmare! Does the evolutionary doctrine clash with religious faith? It does not. It is a blunder to mistake the Holy Scriptures for elementary textbooks of astronomy, geology, biology, and anthropology. Only if symbols are construed to mean what they are not intended to mean can there arise imaginary, insoluble conflicts. As pointed out above, the blunder leads to blasphemy: the Creator is accused of systematic deceitfulness. One of the great thinkers of our age, Pierre Teilhard de Chardin, wrote the following: "Is evolution a theory, a system, or a hypothesis? It is much more it is a general postulate to which all theories, all hypotheses, all systems much henceforward bow and which they must satisfy in order to be thinkable and true. Evolution is a light which illuminates all facts, a trajectory which all lines of though must follow this is what evolution is." Of course, some scientists, as well as some philosophers and theologians, disagree with some parts of Teilhard’s teachings; the acceptance of his worldview falls short of universal. But there is no doubt at all that Teilhard was a truly and deeply religious man and that Christianity was the cornerstone of his worldview. Moreover, in his worldview science and faith were not segregated in watertight compartments, as they are with so many people. They were harmoniously fitting parts of his worldview. Teilhard was a creationist, but one who understood that the Creation is realized in this world by means of evolution.
jueves, 11 de enero de 2007
ESSAY ASSIGNMENT (11th - 12th grade)
IB Biology 11th – 12th Grade
The IB program encourages students to write essays in order to develop critical thinking and writing skills.
Before writting your essays you must have read the articles posted and marked with an (*). Pick the topic of your preference. The essay format that you will find in each of the articles is scientific writing. I am NOT expecting a scientific essay from you, yet.
This is an excercise of both reading and writing, it implicates that you need to read and think before you write your personal analysis of the chosen topic. Use what you have learned so far and look below for writing tips.
Next, I will give you some hints on how to accomplish this task:
Highlight or write down keywords and the main concepts (ideas) of the articles.
Go to your Elephant and Bird books, look for the keywords and search for the concepts (use also wikipedia and google to fully understand the article). If you still have trouble understanding, you are free to ask me directly and/or post your questions and comments in the blog. I will answer A.S.A.P.
With all the information gathered ask yourself:
1. What question am I going to answer in this essay?
2. How can I best answer this question?
3. What is the most important part of my answer?
4. How can I make an introductory sentence (or thesis statement) from the most important part of my answer?
5. What facts or ideas can I use to support my introductory sentence?
6. How can I make this essay interesting?
7. Do I need more facts on this topic?
8. Where can I find more facts on this topic?
9. Should I contact my teacher?
Good luck.
Parts of an Essay
Introduction
Supporting Paragraphs
Summary Paragraph
How to Write an Essay
Prewriting Essays
Writing Essays
Editing Essays
Publishing Essays
Kinds of Essays
Definition
Classification
Description
Compare and Contrast
Sequence
Choice
Explanation
Evaluation
The IB program encourages students to write essays in order to develop critical thinking and writing skills.
Before writting your essays you must have read the articles posted and marked with an (*). Pick the topic of your preference. The essay format that you will find in each of the articles is scientific writing. I am NOT expecting a scientific essay from you, yet.
This is an excercise of both reading and writing, it implicates that you need to read and think before you write your personal analysis of the chosen topic. Use what you have learned so far and look below for writing tips.
Next, I will give you some hints on how to accomplish this task:
Highlight or write down keywords and the main concepts (ideas) of the articles.
Go to your Elephant and Bird books, look for the keywords and search for the concepts (use also wikipedia and google to fully understand the article). If you still have trouble understanding, you are free to ask me directly and/or post your questions and comments in the blog. I will answer A.S.A.P.
With all the information gathered ask yourself:
1. What question am I going to answer in this essay?
2. How can I best answer this question?
3. What is the most important part of my answer?
4. How can I make an introductory sentence (or thesis statement) from the most important part of my answer?
5. What facts or ideas can I use to support my introductory sentence?
6. How can I make this essay interesting?
7. Do I need more facts on this topic?
8. Where can I find more facts on this topic?
9. Should I contact my teacher?
Good luck.
Parts of an Essay
Introduction
Supporting Paragraphs
Summary Paragraph
How to Write an Essay
Prewriting Essays
Writing Essays
Editing Essays
Publishing Essays
Kinds of Essays
Definition
Classification
Description
Compare and Contrast
Sequence
Choice
Explanation
Evaluation
miércoles, 10 de enero de 2007
*Nothing in Biology makes sense except in the Light of Evolution
By: Theodosius Dobzhansky (1900-1975)
geneticist and evolutionary biologist.
Diversity of Living Beings.
The diversity and the unity of life are equally striking and meaningful aspects of the living world. Between 1.5 and 2 million species of animals and plants have been described and studied; the number yet to be described is probably as great. The diversity of sizes, structures, and ways of life is staggering but fascinating. Here are just a few examples.
The foot-and-mouth disease virus is a sphere 8-12 mm in diameter. The blue whale reaches 30 m in length and 135 t in weight. The simplest viruses are parasites in cells of other organisms, reduced to barest essentials minute amounts of DNA or RNA, which subvert the biochemical machinery of the host cells to replicate their genetic information, rather than that of the host.
It is a matter of opinion, or of definition, whether viruses are considered living organisms or peculiar chemical substances. The fact that such differences of opinion can exist is in itself highly significant. It means that the borderline between living and inanimate matter is obliterated. At the opposite end of the simplicity complexity spectrum you have vertebrate animals, including man. The human brain has some 12 billion neurons; the synapses between the neurons are perhaps a thousand times numerous.
Some organisms live in a great variety of environments. Man is at the top of the scale in this respect. He is not only a truly cosmopolitan species but, owing to his technologic achievements, can survive for at least a limited time on the surface of the moon and in cosmic spaces. By contrast, some organisms are amazingly specialized. Perhaps the narrowest ecologic niche of all is that of a species of the fungus family Laboulbeniaceae, which grows exclusively on the rear portion of the elytra of the beetle Aphenops cronei, which is found only in some limestone caves in southern France. Larvae of the fly Psilopa petrolei develop in seepages of crude oil in California oilfields; as far as is known they occur nowhere else. This is the only insect able to live and feed in oil, and its adult can walk on the surface of the oil only as long as no body part other than the tarsi are in contact with the oil. Larvae of the fly Drosophila carciniphila develop only in the nephric grooves beneath the flaps of the third maxilliped of the land crab Geocarcinus ruricola, which is restricted to certain islands in the Caribbean.
Is there an explanation, to make intelligible to reason this colossal diversity of living beings? Whence came these extraordinary, seemingly whimsical and superfluous creatures, like the fungus Laboulbenia, the beetle Aphenops cronei, the flies Psilopa petrolei and Drosophila carciniphila, and many, many more apparent biologic curiosities? The only explanation that makes sense is that the organic diversity has evolved in response to the diversity of environment on the planet earth. No single species, however perfect and however versatile, could exploit all the opportunities for living. Every one of the millions of species has its own way of living and of getting sustenance from the environment. There are doubtless many other possible ways of living as yet unexploited by any existing species; but one thing is clear: with less organic diversity, some opportunities for living would remain unexploited. The evolutionary process tends to fill up the available ecologic niches. It does not do so consciously or deliberately; the relations between evolution and environment are more subtle and more interesting than that. The environment does not impose evolutionary changes on its inhabitants, as postulated by the now abandoned neo-Lamarckian theories. The best way to envisage the situation is as follows: the environment presents challenges to living species, to which the later may respond by adaptive genetic changes.
An unoccupied ecologic niche, an unexploited opportunity for living, is a challenge. So is an environmental change, such as the Ice Age climate giving place to a warmer climate. Natural selection may cause a living species to respond to the challenge by adaptive genetic changes. These changes may enable the species to occupy the formerly empty ecologic niche as a new opportunity for living, or to resist the environmental change if it is unfavorable. But the response may or may not be successful. This depends on many factors, the chief of which is the genetic composition of the responding species at the time the response is called for. Lack of successful response may cause the species to become extinct. The evidence of fossils shows clearly that the eventual end of most evolutionary lines is extinction. Organisms now living are successful descendants of only a minority of the species that lived in the past and of smaller and smaller minorities the farther back you look. Nevertheless, the number of living species has not dwindled; indeed, it has probably grown with time. All this is understandable in the light of evolution theory; but what a senseless operation it would have been, on God’s part, to fabricate a multitude of species ex nihilo and then let most of them die out!
There is, of course, nothing conscious or intentional in the action of natural selection. A biologic species does not say to itself, "Let me try tomorrow (or a million years from now) to grow in a different soil, or use a different food, or subsist on a different body part of a different crab." Only a human being could make such conscious decisions. This is why the species Homo sapiens is the apex of evolution. Natural selection is at one and the same time a blind and creative process. Only a creative and blind process could produce, on the one hand, the tremendous biologic success that is the human species and, on the other, forms of adaptedness as narrow and as constraining as those of the overspecialized fungus, beetle, and flies mentioned above.
Antievolutionists fail to understand how natural selection operates. They fancy that all existing species were generated by supernatural fiat a few thousand years ago, pretty much as we find them today. But what is the sense of having as many as 2 or 3 million species living on earth? If natural selection is the main factor that brings evolution about, any number of species is understandable: natural selection does not work according to a foreordained plan, and species are produced not because they are needed for some purpose but simply because there is an environmental opportunity and genetic wherewithal to make them possible. Was the Creator in a jocular mood when he made Psilopa petrolei for California oil fields and species of Drosophila to live exclusively on some body-parts of certain land crabs on only certain islands in the Caribbean? The organic diversity becomes, however, reasonable and understandable if the Creator has created the living world not by caprice but by evolution propelled by natural selection. It is wrong to hold creation and evolution as mutually exclusive alternatives. I am a creationist and an evolutionist. Evolution is God’s, or Nature’s method of creation. Creation is not an event that happened in 4004 BC; it is a process that began some 10 billion years ago and is still under way.
geneticist and evolutionary biologist.
Diversity of Living Beings.
The diversity and the unity of life are equally striking and meaningful aspects of the living world. Between 1.5 and 2 million species of animals and plants have been described and studied; the number yet to be described is probably as great. The diversity of sizes, structures, and ways of life is staggering but fascinating. Here are just a few examples.
The foot-and-mouth disease virus is a sphere 8-12 mm in diameter. The blue whale reaches 30 m in length and 135 t in weight. The simplest viruses are parasites in cells of other organisms, reduced to barest essentials minute amounts of DNA or RNA, which subvert the biochemical machinery of the host cells to replicate their genetic information, rather than that of the host.
It is a matter of opinion, or of definition, whether viruses are considered living organisms or peculiar chemical substances. The fact that such differences of opinion can exist is in itself highly significant. It means that the borderline between living and inanimate matter is obliterated. At the opposite end of the simplicity complexity spectrum you have vertebrate animals, including man. The human brain has some 12 billion neurons; the synapses between the neurons are perhaps a thousand times numerous.
Some organisms live in a great variety of environments. Man is at the top of the scale in this respect. He is not only a truly cosmopolitan species but, owing to his technologic achievements, can survive for at least a limited time on the surface of the moon and in cosmic spaces. By contrast, some organisms are amazingly specialized. Perhaps the narrowest ecologic niche of all is that of a species of the fungus family Laboulbeniaceae, which grows exclusively on the rear portion of the elytra of the beetle Aphenops cronei, which is found only in some limestone caves in southern France. Larvae of the fly Psilopa petrolei develop in seepages of crude oil in California oilfields; as far as is known they occur nowhere else. This is the only insect able to live and feed in oil, and its adult can walk on the surface of the oil only as long as no body part other than the tarsi are in contact with the oil. Larvae of the fly Drosophila carciniphila develop only in the nephric grooves beneath the flaps of the third maxilliped of the land crab Geocarcinus ruricola, which is restricted to certain islands in the Caribbean.
Is there an explanation, to make intelligible to reason this colossal diversity of living beings? Whence came these extraordinary, seemingly whimsical and superfluous creatures, like the fungus Laboulbenia, the beetle Aphenops cronei, the flies Psilopa petrolei and Drosophila carciniphila, and many, many more apparent biologic curiosities? The only explanation that makes sense is that the organic diversity has evolved in response to the diversity of environment on the planet earth. No single species, however perfect and however versatile, could exploit all the opportunities for living. Every one of the millions of species has its own way of living and of getting sustenance from the environment. There are doubtless many other possible ways of living as yet unexploited by any existing species; but one thing is clear: with less organic diversity, some opportunities for living would remain unexploited. The evolutionary process tends to fill up the available ecologic niches. It does not do so consciously or deliberately; the relations between evolution and environment are more subtle and more interesting than that. The environment does not impose evolutionary changes on its inhabitants, as postulated by the now abandoned neo-Lamarckian theories. The best way to envisage the situation is as follows: the environment presents challenges to living species, to which the later may respond by adaptive genetic changes.
An unoccupied ecologic niche, an unexploited opportunity for living, is a challenge. So is an environmental change, such as the Ice Age climate giving place to a warmer climate. Natural selection may cause a living species to respond to the challenge by adaptive genetic changes. These changes may enable the species to occupy the formerly empty ecologic niche as a new opportunity for living, or to resist the environmental change if it is unfavorable. But the response may or may not be successful. This depends on many factors, the chief of which is the genetic composition of the responding species at the time the response is called for. Lack of successful response may cause the species to become extinct. The evidence of fossils shows clearly that the eventual end of most evolutionary lines is extinction. Organisms now living are successful descendants of only a minority of the species that lived in the past and of smaller and smaller minorities the farther back you look. Nevertheless, the number of living species has not dwindled; indeed, it has probably grown with time. All this is understandable in the light of evolution theory; but what a senseless operation it would have been, on God’s part, to fabricate a multitude of species ex nihilo and then let most of them die out!
There is, of course, nothing conscious or intentional in the action of natural selection. A biologic species does not say to itself, "Let me try tomorrow (or a million years from now) to grow in a different soil, or use a different food, or subsist on a different body part of a different crab." Only a human being could make such conscious decisions. This is why the species Homo sapiens is the apex of evolution. Natural selection is at one and the same time a blind and creative process. Only a creative and blind process could produce, on the one hand, the tremendous biologic success that is the human species and, on the other, forms of adaptedness as narrow and as constraining as those of the overspecialized fungus, beetle, and flies mentioned above.
Antievolutionists fail to understand how natural selection operates. They fancy that all existing species were generated by supernatural fiat a few thousand years ago, pretty much as we find them today. But what is the sense of having as many as 2 or 3 million species living on earth? If natural selection is the main factor that brings evolution about, any number of species is understandable: natural selection does not work according to a foreordained plan, and species are produced not because they are needed for some purpose but simply because there is an environmental opportunity and genetic wherewithal to make them possible. Was the Creator in a jocular mood when he made Psilopa petrolei for California oil fields and species of Drosophila to live exclusively on some body-parts of certain land crabs on only certain islands in the Caribbean? The organic diversity becomes, however, reasonable and understandable if the Creator has created the living world not by caprice but by evolution propelled by natural selection. It is wrong to hold creation and evolution as mutually exclusive alternatives. I am a creationist and an evolutionist. Evolution is God’s, or Nature’s method of creation. Creation is not an event that happened in 4004 BC; it is a process that began some 10 billion years ago and is still under way.
jueves, 4 de enero de 2007
GUIDE TO BIOLOGY EXTENDED ESSAY
THE EXTENDED ESSAY FOR BIOLOGY
1st quarter: Subject Idea and Research Approach (General Theme, sources of information and methods for analysis)
2nd quarter: Research Question and Hypothesis (based on the research question)
Mid-Term: Preliminar Title, Research Question and Hypothesis, Review of reference sources.
3rd quarter: Outline (Rough Draft) Variable definition, Analysis and interpretation of data, Conclusions
4th quarter: Final Drafts for 12th grade also including:
· An abstract of the research project
· Research Question and Hypothesis
· Introduction (Background information)
· Data Analysis and evaluation of the obtained results
. Argument
. Conclusion
. Text references (bibliographic entries especially for web based resources)
· Diagrams and illustrations
. Appendix (if necessary)
Read the following Report if you have any doubts
1st quarter: Subject Idea and Research Approach (General Theme, sources of information and methods for analysis)
2nd quarter: Research Question and Hypothesis (based on the research question)
Mid-Term: Preliminar Title, Research Question and Hypothesis, Review of reference sources.
3rd quarter: Outline (Rough Draft) Variable definition, Analysis and interpretation of data, Conclusions
4th quarter: Final Drafts for 12th grade also including:
· An abstract of the research project
· Research Question and Hypothesis
· Introduction (Background information)
· Data Analysis and evaluation of the obtained results
. Argument
. Conclusion
. Text references (bibliographic entries especially for web based resources)
· Diagrams and illustrations
. Appendix (if necessary)
Read the following Report if you have any doubts
EXTENDED ESSAY REPORTS – MAY 2004 Biology
The extended essay in biology is an opportunity for candidates to apply independent research skills and methodology appropriate to the subject. The subject matter must be biological, must lend itself to investigation through biological research methods, must be at a theoretical level which is suitable for pre-university students and must allow the candidate sufficient room to demonstrate personal initiative and engagement. The report is intended to provide feedback on the performance of candidates and to act as a guide for the supervision of future candidates. As such it is primarily addressed to supervisors, in an effort to highlight those areas where candidates are in need of specific guidance and supervision.
The quality, and to a lesser extent the quantity, of supervision received by a candidate can a play a major role in the success of an extended essay. Comments made by the supervisor on the circumstance surrounding the research and level of personal involvement of the candidates can also be of considerable assistance to the examiners.
Range and suitability of the work submitted
Appropriate topics in biology include ecology, genetics, evolution, animal and plant physiology, biochemistry, biotechnology, microbiology, and a wide variety of human biology topics including behaviour, exercise physiology, health, drugs, nutrition and diseases. The most successful research based papers had a small number of clearly defined and easily manipulated independent variables and a quantifiable and easily measured dependent variable. Successful essays often rely on a small amount of simple equipment and can be carried out in the school laboratory or in the local environment.
While literature-based essays per se are not inappropriate, those that rely exclusively on web-based sources run the risk of failing to adequately meet particular criteria (especially the subject specific). These essays are often poorly illustrated and inadequately referenced and show little or no sense of the reliability, or otherwise, of the sources accessed. They tend also to be accumulations of fact with little or no attempt to analyse or critically evaluate.
Choice of topic is crucial to the overall success of the essay and candidates need guidance in selecting an appropriate topic. Inappropriate and or poorly focused topics include ethical, social and religious aspects of biological issues, political and economic aspects of environmental policy, and diagnosis and treatment of disorders and diseases. This is an area where supervisors need to exert more influence. The topic should result from a discussion between the candidate and the supervisor during which a process of identifying, discussing, assessing and narrowing down a suitable area for research is undertaken, and the interest and motivation of the candidate are channeled in an appropriate direction.
Candidate performance against each criterion
General assessment criteria
Criterion A Research question
Essays with a clearly defined, well focused research question tended to be those that were based on experimental work carried out by the candidate. The best essays include a hypothesis or small number of hypotheses which are based on the research question. Good essays will also refer to the research question in the discussion and will establish the extent to which it has been answered in the conclusion. Candidates need guidance on how to avoid inappropriate, poorly focused, or even trivial, research questions. Some reading and preliminary research should take place before the final selection of the research question. Candidates must ensure that the research question is stated "in the early part of the essay" (in the first two pages or so).
Criterion B Approach to the research question
Most candidates are able to select a broadly suitable research approach. Weaknesses occur in the case of experimentally based essays when the candidate fails to establish suitable experimental controls or fails to elaborate on all of the relevant variables. A weakness in the approach to library-based essays is often the heavy or even exclusive reliance on one type of source (web-based sources or newspaper articles). Few candidates attempt to explain or justify the research approach and in some cases it is evident that the candidate has not been involved in this part of the research process. This is especially evident in cases where the topic is part of a bigger research project with its well established approach. It is helpful and appropriate to give a brief account of preliminary research that was used to arrive at the final approach.
Criterion C Analysis/interpretation
Examiners report a wide range of standards for the criterion, ranging from essays with no analysis to very sophisticated statistical treatments. While candidates should be encouraged to use statistical analysis where appropriate, they must also be selective about the techniques used and should be encouraged to explain and justify their approach. Simply graphing the raw data does not represent data analysis. It is often helpful, if there is a large body of raw data, for this to be included in an appendix and for summary charts and tables to be in the main body of the essay.
Library-based essays often fail to address this criterion well. The exceptions include cases where the candidate analyses published data or attempts to re-evaluate information from a range of sources.
Criterion D Argument/evaluation
In order to build up an effective argument, the candidate must regularly refer back to the research question and/or hypothesis. This helps to make the argument explicit. The candidate must make it clear how the data and information being presented in the essay help to answer the research question. Few candidates take a systematic approach to building up an argument. Weak essays introduce new ideas and arguments, that are not related to either the research question or the data/information presented, at a late stage in the discussion.
Criterion E Conclusion
While few candidates had difficulty writing a conclusion restating the main findings of the research, examiners report that in many cases candidates fail to refer to unresolved questions and new questions that have arisen as a result of the research. In a good conclusion the candidate will refer back to the research question or the hypothesis derived from this and say to what extent the question has been answered or the hypothesis supported.
Criterion F Abstract
Few candidates pay attention to the requirement for three aspects to an abstract: research question, scope and conclusion. Weak essays have an abstract which is a kind of "justification" for the choice of topic or simply a summary of the introduction. The most difficult aspect of this criterion seems to be dealing adequately with the scope of the research. Few candidates point out how the research was conducted or how the limits of the research were defined. This is particularly noticeable in library-based essays.
Criterion G Formal presentation
The use of word processing and data analysis software has raised the standard of presentation generally to the extent that even weak candidates can produce a well presented essay. There are still a number of problems where candidates need guidance:
· Candidates need to be selective about what they include in the appendix. An appendix should only be part of the essay if it is necessary. Important data should be in the body of the essay.
· Many candidates do not follow a consistent, standard style for in text referencing. Some candidates are clearly confused about citations, quotations, footnotes, endnotes and bibliographic references and are clearly in need of guidance on this. Most library-based essays are poorly referenced.
· Some essays have no obvious structure. This is often reflected in a table of contents along the lines of "introduction, body, and conclusion". In other cases candidates use headings in the table of contents which do not appear in the text of the essay.
· Candidates tend not to make good use of supporting illustrative material. On the one hand diagrams and pictures are sometimes copied directly from the sources and included in the essay with no commentary or no attempt to explain or highlight their context. Photographs should be carefully selected and should only be included if they enhance the quality of work.
Criterion H Holistic judgement
A well written comment from the school or external supervisor can help to establish the level of inventiveness and flair displayed by the candidate and can be of great assistance to the examiner in awarding the most appropriate level of achievement for this criterion. As mentioned above, however, many supervisors fail to provide any comment and it is left up to the examiner to try to glean the level of personal engagement of the candidate. It is particularly difficult for candidates who undertake library based research, or experimental research at an outside institution, to demonstrate the attributes included in this criterion and it is therefore particularly important for the supervisors to provide an appropriate comment.
Subject assessment criteria
Candidates who perform their own research (school based, experimental or field study) tend to meet the biological criteria to a high standard. Such candidates are in a better position to demonstrate an understanding of the underlying biological principles, to provide evidence of a personal approach and to be willing (and able) to undertake a critical evaluation of their work.
Criterion J Biological study of living organisms
With the exception of those inappropriate essays mentioned earlier, most essays in this session dealt with biological issues. There is a tendency for biochemical topics to stray into chemical issues and for environmental essays to deal with geographical or even cultural and economic issues at the expense of biology. An ongoing problem relates to essays dealing with diagnosis and treatment of human diseases. These tend to score poorly if the underlying biological phenomena are not dealt with.
Criterion K Use of methods and sources appropriate to biology
Few candidates write about the reliability or appropriateness of the sources they have used. In cases where the work is carried out at a research institution or university, it is often difficult if not impossible for the candidate to provide evidence of a personal approach in the choice and application of research methods and sources used.
Criterion L Analysis of the limitations surrounding the research
This is often by far the weakest criterion. Few candidates attempt to critically evaluate their own work and seem reluctant to scrutinize the work of others. This is a crucial part of the research process and candidates need to learn not to take printed or web based information or data at face value. Candidates need to be shown that pointing out weaknesses in the data or information improves the quality of the research.
Recommendations for the supervision of future candidates
The amount of time that many supervisors spend with the candidate is insufficient (often less than one hour). Candidates need guidance on several aspects of the writing and research process and this can only be achieved on an ongoing basis. Biology is one of the most popular subject choices for the extended essay and supervisors in many schools may be stretched to meet the needs of their students. However effective supervision is a crucial part of the learning process involved in writing the extended essay. Without effective ongoing supervision the process becomes a chore for the candidate and a fruitless exercise in the end.
The reasons for the need for close and effective supervision have been amply discussed in previous reports. The evidence from this session once again is that those candidates who receive appropriate supervision rarely fail to meet the mechanical aspects of the assessment criteria and are in a better position to do well on the others, while those left to their own devices tend to do poorly.
Candidates are in need of guidance on the following points:
· writing an abstract
· constructing an effective argument
· establishing, refining and using the research question
· referencing the text
· bibliographic entries especially for web based resources
· structuring the essay (headings and sub headings)
· writing a critical evaluation
· incorporating and integrating diagrams and illustrations
· creating effective controls for experiments
· selecting material for inclusion in an appendix.
Candidates should be discouraged from submitting work which has been conducted as part of a research team at a university or research institute for the extended essay unless it can be shown that the candidate has had a sufficient level of input into the research approach and selection of methodology and sources. The supervisors at the outside institution should be apprised of the assessment criteria and be asked to ensure that the candidate will have ample opportunity to work independently. "Outsourcing" the supervision of the extended essay in this manner might seem like an "easy option" but in fact does not meet the spirit or the intent of the extended essay process and puts the candidate at a disadvantage in the assessment process. If the school cannot provide supervision for a school-based research topic in biology then the candidate should chose a different subject.
AISB RECYCLING CAMPAIGN (IB Project)
IB Biology: Grades 11 - 12
Topic: Recyling Project
The Recycling Project is an IB requirement.
The project involves all IB Biology students.
We will make the presentations the first week of school and continue the follow up throughout the semester.
Starting on January 15th, IB students will make sure everybody recycles on campus.
Objectives:
-To start the recycling campaign in AISB.
-Inform all grades and staff members about the benefits of recycling in school.
-Show everybody how to sort the trash in school from now on.
-Explain the three R’s in recycling (Reuse, Reduce, Recycle).
-Comment on the importance of reusing, reducing and recycling.
Activities:
-IB students have prepared presentations and games to show everybody in school how to carry on a recycling project on campus.
-Every classroom will be visited by IB Biology students to learn about recycling.
-Caffeteria members will also be visited during this week’s campaign.
-Staff members will also be informed about the campaign.
-Every recess and lunch break will be supervised by groups of students that will encourage everybody to use the proper bins for the trash.
Topic: Recyling Project
The Recycling Project is an IB requirement.
The project involves all IB Biology students.
We will make the presentations the first week of school and continue the follow up throughout the semester.
Starting on January 15th, IB students will make sure everybody recycles on campus.
Objectives:
-To start the recycling campaign in AISB.
-Inform all grades and staff members about the benefits of recycling in school.
-Show everybody how to sort the trash in school from now on.
-Explain the three R’s in recycling (Reuse, Reduce, Recycle).
-Comment on the importance of reusing, reducing and recycling.
Activities:
-IB students have prepared presentations and games to show everybody in school how to carry on a recycling project on campus.
-Every classroom will be visited by IB Biology students to learn about recycling.
-Caffeteria members will also be visited during this week’s campaign.
-Staff members will also be informed about the campaign.
-Every recess and lunch break will be supervised by groups of students that will encourage everybody to use the proper bins for the trash.
12th grade 2006 lesson plans
IB Biology: Grade 12
Topic: Digestion and Human Nutrition
Objectives:
- Explain the importance of nutrients in human diet.
- Discuss the characteristics of the main molecules present in food (water, carbohydrates, lipids, proteins, vitamins, and enzymes.
- Describe the organs and functions of the digestive system.
- Distinguish between absorption and assimilation.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and physiology of the digestive system.
Topic: Respiration and gas exchange
Objectives:
- Understand the control mechanisms of respiration and the functions of the organs involved.
- Discuss the phases of respiration and remark the differences between cellular respiration and gas exchange.
- Distinguish the different kinds of respiratory surfaces in kingdom Animalia.
- Explain the Human Respiratory System and the mechanism of gas exchange in the alveoli.
Content:
- Nasal passage, pharynx, larynx, trachea, lungs, bronchi, alveoli.
- The process of respiration. Anatomy and physiology of the respiratory system. A brief comparison among different phylum in Animalia kingdom.
Topic: Respiration and Circulation
Objectives:
- Understand the control mechanisms of respiration and circulation.
- State the process of diffusion between alveolar chambers and blood.
- To get familiar with the diffusion between blood and cells.
Content:
- Diffusion between alveolar chambers and blood
- Diffusion between blood and cells
- Bulk flow of O2
- The process of respiration. Control of respiration,
- Open and closed circulatory systems
Topic: Circulatory System
Objectives:
- Understand the control mechanisms of the heart in blood circulation.
- State the process that are carried out in the circulatory system.
- To get familiar with the transport systems through veins and arteries.
Content:
- The process of circulation. Control of circulation.
- Open and closed circulatory systems.
- Systemic and pulmonary circulation.
Topic: Digestion and Human Nutrition
Objectives:
- Explain the importance of nutrients in human diet.
- Discuss the characteristics of the main molecules present in food (water, carbohydrates, lipids, proteins, vitamins, and enzymes.
- Describe the organs and functions of the digestive system.
- Distinguish between absorption and assimilation.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and physiology of the digestive system.
Topic: Respiration and gas exchange
Objectives:
- Understand the control mechanisms of respiration and the functions of the organs involved.
- Discuss the phases of respiration and remark the differences between cellular respiration and gas exchange.
- Distinguish the different kinds of respiratory surfaces in kingdom Animalia.
- Explain the Human Respiratory System and the mechanism of gas exchange in the alveoli.
Content:
- Nasal passage, pharynx, larynx, trachea, lungs, bronchi, alveoli.
- The process of respiration. Anatomy and physiology of the respiratory system. A brief comparison among different phylum in Animalia kingdom.
Topic: Respiration and Circulation
Objectives:
- Understand the control mechanisms of respiration and circulation.
- State the process of diffusion between alveolar chambers and blood.
- To get familiar with the diffusion between blood and cells.
Content:
- Diffusion between alveolar chambers and blood
- Diffusion between blood and cells
- Bulk flow of O2
- The process of respiration. Control of respiration,
- Open and closed circulatory systems
Topic: Circulatory System
Objectives:
- Understand the control mechanisms of the heart in blood circulation.
- State the process that are carried out in the circulatory system.
- To get familiar with the transport systems through veins and arteries.
Content:
- The process of circulation. Control of circulation.
- Open and closed circulatory systems.
- Systemic and pulmonary circulation.
11th grade 2006 lesson plans
IB Biology: Grade 11
Topic: IB Lab: the Microscope
Objectives:
- Understand the IB format of lab preparation.
- To complete the first lab of the IB program.
- Describe the parts of the light microscope and its use.
- Learn to prepare a wet mount slide.
Content:
- Safety in the lab.
- Parts of the light microscope.
- Observing a prepared slide.
Topic: Chemical Basis of Biology
Objectives:
- Understand the properties and importance of water in living organisms.
- Describe the organic molecules.
- Learn the structural organization and main functions of carbohydrates, lipids, enzymes, proteins and nucleic acids.
Content:
- Water: Ways of bonding, properties.
- Carbohydrates: Sugars and Starches.
- Lipids: Structures and Functions in the cells and organisms.
- Proteins: Levels of organization.
- Nucleotides and Nucleic Acids: Functions, Information molecules.
- DNA.
- RNA.
Topic: IB Lab: the Microscope
Objectives:
- Understand the IB format of lab preparation.
- To complete the first lab of the IB program.
- Describe the parts of the light microscope and its use.
- Learn to prepare a wet mount slide.
Content:
- Safety in the lab.
- Parts of the light microscope.
- Observing a prepared slide.
Topic: Chemical Basis of Biology
Objectives:
- Understand the properties and importance of water in living organisms.
- Describe the organic molecules.
- Learn the structural organization and main functions of carbohydrates, lipids, enzymes, proteins and nucleic acids.
Content:
- Water: Ways of bonding, properties.
- Carbohydrates: Sugars and Starches.
- Lipids: Structures and Functions in the cells and organisms.
- Proteins: Levels of organization.
- Nucleotides and Nucleic Acids: Functions, Information molecules.
- DNA.
- RNA.
9th grade 2006 lesson plans
Biology: 9th Grade
Topic: Protists and Fungi
Objectives:
- Review characteristics of Protists
- Describe the major characteristics of Fungi.
- Compare mushrooms, yeasts and molds.
- Discuss ways in which fungi interact with other living things.
Content:
- Habitats and ways of life of fungi.
- Classification.
- Kinds of fungi: Mushrooms, Yeasts and Molds.
Topic: Digestive system and Nutrition
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion.
- Anatomy and physiology of the digestive system.
Topic: Gas exchange and Transport Systems
Objectives:
- Understand the control mechanisms of respiration and the functions of the organs involved.
- Discuss the phases of respiration and remark the differences between cellular respiration and gas exchange.
- Distinguish the different kinds of respiratory surfaces in kingdom Animalia.
- Explain the Human Respiratory System and the mechanism of gas exchange in the alveoli.
Content:
- Nasal passage, pharynx, larynx, trachea, lungs, bronchi, alveoli.
- The process of respiration. Anatomy and physiology of the respiratory system. A brief comparison among different phylum in Animalia kingdom.
Topic: Circulation and Excretion (Introduction to Homeostasis)
Objectives:
- Understand the control mechanisms of homeostasis
- Discuss the phases of the transport and excretion of substances
- State the difference between excretion and secretion
- Explain balance and self-regulation
- Understand the circulatory system and its multiple functions in the body
Content:
- Equilibrium and balance in living organisms
- Cells and the medium
- Homeostasis
Topic: Homeostasis and inner balance
Objectives:
- To integrate the different topics studied during this semester
- Understand the mechanisms of temperature regulation
- Introduction to the defense mechanisms of the body
- Understand the process of water balance
- Review excretory system
- Compare the functions of excretion and respiration in waste removal
Content:
- Temperature regulation in cold blooded and warm blooded vertebrates
- Excretion and water balance
- Immune Response
Topic: Protists and Fungi
Objectives:
- Review characteristics of Protists
- Describe the major characteristics of Fungi.
- Compare mushrooms, yeasts and molds.
- Discuss ways in which fungi interact with other living things.
Content:
- Habitats and ways of life of fungi.
- Classification.
- Kinds of fungi: Mushrooms, Yeasts and Molds.
Topic: Digestive system and Nutrition
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion.
- Anatomy and physiology of the digestive system.
Topic: Gas exchange and Transport Systems
Objectives:
- Understand the control mechanisms of respiration and the functions of the organs involved.
- Discuss the phases of respiration and remark the differences between cellular respiration and gas exchange.
- Distinguish the different kinds of respiratory surfaces in kingdom Animalia.
- Explain the Human Respiratory System and the mechanism of gas exchange in the alveoli.
Content:
- Nasal passage, pharynx, larynx, trachea, lungs, bronchi, alveoli.
- The process of respiration. Anatomy and physiology of the respiratory system. A brief comparison among different phylum in Animalia kingdom.
Topic: Circulation and Excretion (Introduction to Homeostasis)
Objectives:
- Understand the control mechanisms of homeostasis
- Discuss the phases of the transport and excretion of substances
- State the difference between excretion and secretion
- Explain balance and self-regulation
- Understand the circulatory system and its multiple functions in the body
Content:
- Equilibrium and balance in living organisms
- Cells and the medium
- Homeostasis
Topic: Homeostasis and inner balance
Objectives:
- To integrate the different topics studied during this semester
- Understand the mechanisms of temperature regulation
- Introduction to the defense mechanisms of the body
- Understand the process of water balance
- Review excretory system
- Compare the functions of excretion and respiration in waste removal
Content:
- Temperature regulation in cold blooded and warm blooded vertebrates
- Excretion and water balance
- Immune Response
8th grade 2006 lesson plans
Biology: 8th Grade
Topic: Coldblooded Vertebrates
Objectives:
- To describe the general characteristics of vertebrates.
- Compare warmblooded and coldblooded vertebrates.
Content:
- Characteristics of vertebrates
- Fish: the tree classes of fish
- Amphibians (metamorphosis on frogs)
- Reptiles and their adaptations to live on land.
Topic: Warmblooded Vertebrates
Objectives:
- To describe the general characteristics of vertebrates.
- Compare warmblooded and coldblooded vertebrates.
- Quiz on coldblooded vertebrates
Content:
- Amphibians (metamorphosis on frogs).
- Reptiles and their adaptations to live on land.
- Warmblooded vertebrates
Topic: Mammals: Monotremes, Marsupials and Placental
Objectives:
- Quiz on Cold Blooded Vertebrates.
- Mammals. Monotremes, Marsupial, Placental.
- Origin of First Mammals. Continental drift and specialization
Topic: Placental Mammals Orders: Insectivora, Edentata, Lagomorpha
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Placental Mammals Orders: Rodentia, Lagomorpha, Perissodactyla, Chiroptera
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Placental Mammals Orders: Sirenia and Cetacea
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Earth Biomes (final presentations)
Objectives:
- Describe the major characteristics of the different biomes
- List and describe the most representative animals that live in each biome
- State the most relevant types of specilization that each animal needs to develop for its adaptation in the different biomes
Topic: Coldblooded Vertebrates
Objectives:
- To describe the general characteristics of vertebrates.
- Compare warmblooded and coldblooded vertebrates.
Content:
- Characteristics of vertebrates
- Fish: the tree classes of fish
- Amphibians (metamorphosis on frogs)
- Reptiles and their adaptations to live on land.
Topic: Warmblooded Vertebrates
Objectives:
- To describe the general characteristics of vertebrates.
- Compare warmblooded and coldblooded vertebrates.
- Quiz on coldblooded vertebrates
Content:
- Amphibians (metamorphosis on frogs).
- Reptiles and their adaptations to live on land.
- Warmblooded vertebrates
Topic: Mammals: Monotremes, Marsupials and Placental
Objectives:
- Quiz on Cold Blooded Vertebrates.
- Mammals. Monotremes, Marsupial, Placental.
- Origin of First Mammals. Continental drift and specialization
Topic: Placental Mammals Orders: Insectivora, Edentata, Lagomorpha
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Placental Mammals Orders: Rodentia, Lagomorpha, Perissodactyla, Chiroptera
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Placental Mammals Orders: Sirenia and Cetacea
Objectives:
- Describe the major characteristics of each Order of Mammals.
- State the similarities and differences among the different groups within the Order.
- Explain and compare the major habits of each Order.
Topic: Earth Biomes (final presentations)
Objectives:
- Describe the major characteristics of the different biomes
- List and describe the most representative animals that live in each biome
- State the most relevant types of specilization that each animal needs to develop for its adaptation in the different biomes
7th grade 2006 lesson plans
Life Science: 7th Grade
Topic: Digestive system and Nutrition
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and fisiology of the digestive system.
Topic: Respiratory and Excretory Systems
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and fisiology of the digestive system.
Topic: Respiratory system and Respiration
Objectives:
- Explain the mechanism of respiration
- Describe the organs and functions of the respiratory system.
- Understand the importance of gas exchange (O2 and CO2)
Content:
- Nose, nostrils, pharynx, larynx, trachea, lungs, bronchi, alveoli
- The process of respiration. Anatomy and physiology of the respiratory system.
Topic: Excretion
Objectives:
- Compare different Structures for gas exchange among animals
- Understand the importance of excretion
Content:
- Kidneys, ureters, urinary bladder, urethra.
- The process of filtration in the kidneys. Anatomy and physiology of the kidney and nephron
Topic: Circulatory System
Objectives:
- Understand the process of blood circulation.
- State the functions of the heart.
- To get familiar with the transport systems through veins and arteries
Content:
- The process of circulation. Control of circulation
- The Heart
- Circulation through veins and arteries
Topic: Nervous System (Final Presentations)
Objectives:
- Describe the function of the nervous system
- Identify the structures of a neuron
- Describe a nerve impulse
- List the structures and functions of the central nervous Describe the peripheral and autonomic nervous systems
- Describe the functions of the five sense organs
- Describe the functions of the brain
Content:
- Sructure and function of the nervous system.
- The Central Nervous System
- The Peripheral Nervous System
- The senses
Topic: Digestive system and Nutrition
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and fisiology of the digestive system.
Topic: Respiratory and Excretory Systems
Objectives:
- Explain the importance of eating.
- Identify the main nutrients and how they are used by the body.
- Describe the organs and functions of the digestive system.
- Define balanced diet and tell why it is important.
Content:
- Water, minerals, carbohydrates, fats, proteins, vitamins, enzymes.
- The process of digestion. Anatomy and fisiology of the digestive system.
Topic: Respiratory system and Respiration
Objectives:
- Explain the mechanism of respiration
- Describe the organs and functions of the respiratory system.
- Understand the importance of gas exchange (O2 and CO2)
Content:
- Nose, nostrils, pharynx, larynx, trachea, lungs, bronchi, alveoli
- The process of respiration. Anatomy and physiology of the respiratory system.
Topic: Excretion
Objectives:
- Compare different Structures for gas exchange among animals
- Understand the importance of excretion
Content:
- Kidneys, ureters, urinary bladder, urethra.
- The process of filtration in the kidneys. Anatomy and physiology of the kidney and nephron
Topic: Circulatory System
Objectives:
- Understand the process of blood circulation.
- State the functions of the heart.
- To get familiar with the transport systems through veins and arteries
Content:
- The process of circulation. Control of circulation
- The Heart
- Circulation through veins and arteries
Topic: Nervous System (Final Presentations)
Objectives:
- Describe the function of the nervous system
- Identify the structures of a neuron
- Describe a nerve impulse
- List the structures and functions of the central nervous Describe the peripheral and autonomic nervous systems
- Describe the functions of the five sense organs
- Describe the functions of the brain
Content:
- Sructure and function of the nervous system.
- The Central Nervous System
- The Peripheral Nervous System
- The senses
martes, 2 de enero de 2007
*Evolution of Sexual Reproduction
Evolution of sex
The evolution of sex is a major puzzle in modern Biology. Many groups of organisms, notably the majority of animals and plants, reproduce sexually. The evolution of sex contains two related, yet distinct, themes: its origin and its maintenance. However, since the hypotheses for the origins of sex are difficult to test experimentally, most current work has been focused on the maintenance of sexual reproduction. Several explanations have been suggested by biologists including W. D. Hamilton, Alexey Kondrashov, and George C. Williams to explain how sexual reproduction is maintained in a vast array of different living organisms.
It seems that a sexual cycle is maintained because it improves the quality of progeny (fitness), despite reducing the overall number of offspring (two-fold cost of sex). In order for sex to be evolutionarily advantageous, it must be associated with a significant increase in the fitness of offspring. One of the most widely accepted explanations for the advantage of sex lies in the creation of genetic variation. There are three possible reasons why this might happen. First, sexual reproduction can bring together mutations that are beneficial into the same individual (sex aids in the spread of advantageous traits). Second, sex acts to bring together currently deleterious mutations to create severely unfit individuals that are then eliminated from the population (sex aids in the removal of deleterious genes). Last, sex creates new gene combinations that may be more fit than previously existing ones, or may simply lead to reduced competition among relatives.
The evolution of sex is a major puzzle in modern Biology. Many groups of organisms, notably the majority of animals and plants, reproduce sexually. The evolution of sex contains two related, yet distinct, themes: its origin and its maintenance. However, since the hypotheses for the origins of sex are difficult to test experimentally, most current work has been focused on the maintenance of sexual reproduction. Several explanations have been suggested by biologists including W. D. Hamilton, Alexey Kondrashov, and George C. Williams to explain how sexual reproduction is maintained in a vast array of different living organisms.
It seems that a sexual cycle is maintained because it improves the quality of progeny (fitness), despite reducing the overall number of offspring (two-fold cost of sex). In order for sex to be evolutionarily advantageous, it must be associated with a significant increase in the fitness of offspring. One of the most widely accepted explanations for the advantage of sex lies in the creation of genetic variation. There are three possible reasons why this might happen. First, sexual reproduction can bring together mutations that are beneficial into the same individual (sex aids in the spread of advantageous traits). Second, sex acts to bring together currently deleterious mutations to create severely unfit individuals that are then eliminated from the population (sex aids in the removal of deleterious genes). Last, sex creates new gene combinations that may be more fit than previously existing ones, or may simply lead to reduced competition among relatives.
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