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1. Plants, animals and fungi are made up of many cells – thus, they are called “ multicellular organisms.” We talked in class about three types of evidence that those groups of organisms evolved multicellularity independently. In other words, plants, animals and fungi each arose independently from single-celled ancestors. What are those three pieces of evidence?Explain why each of those is evidence for the independent origin of multicellularity , and be specific! Also, list four features (other than multicellularity ) that plants, animals and fungi all have in common. What do those common features suggest to you?
note 1: "A" "C" "T" and "G" do not count as four different features that fungi plants and animals have in common.
note 2: note 1 is a hint
2. You are working for the centers for disease control, and you get a call on the phone from your field office in Michigan. 10 people have become sick with a flu-like illness that has never before been described. You fly out to Michigan and investigate. One of the sick individuals is a mink farmer. You go to visit him in the hospital, and he tells you that he was bit by one of his animals on January 10. He started to feel sick on January 17. His wife, who works as a teacher in a local day care center, then got sick on January 20, and then, in the next week, several of the kids who attend that day care, and three of their parents, also became sick. Blood samples taken from the patients have shown that they have a new variant of a flu virus. Blood samples from the minks from the farm show that several of them have the same flu virus as well. But the minks are perfectly healthy.
Is this virus causing the illnesses in those patients or not? Formulate a hypothesis to explain the information above, and come up with two or three experiments to test that hypothesis. For EACH experiment, suggest what the different possible results might be. Finally, say what you would conclude from those results.
3. For this question, let’s assume that the new mink virus did cause the flu-like illness in humans. How would you explain why the minks are not sick?
4a) It’s San Jose in the year 2005, and they are considering instituting a needle-exchange program to try to slow the spread of HIV among the intravenous drug users in the city. A city council meeting has been called on the topic, and you have been asked to speak as an expert witness. You are asked to address the following questions in your presentation: First, do needle exchange programs encourage the use of drugs? And second, is there any evidence that needle exchange programs actually slow the spread of HIV among intravenous drug users? You know that these politicians need to hear specific information on these questions. Luckily, on the train up to San Jose from Salinas , you were reading your copy of “The Global Impact of HIV” by Plot et al.
You get up in front of the city council and say….
4b) Your cousin is HIV positive, and is supposed to be taking a cocktail of two drugs: one is a protease inhibitor, and the other is a reverse transcriptase inhibitor. Your cousin tells you that the drugs have become too expensive for him, so what he has decided to do is to take only the protease inhibitor for a while (2 years or so), and then switch to taking only the reverse transcriptase inhibitor. He knows you are a biology student, and therefore you know quite a bit about HIV and AIDS, so he asks you if this is a good idea. What would you tell him? Your cousin wants all the relevant information, so make sure you tell him about how the human immune system reacts to HIV, how the drugs work, and how HIV responds to these drugs.
5) According to Charles Darwin, artificial selection (for example, animal breeding) is similar to natural selection. What’s the difference? And assuming that everyone agrees that artificial selection has resulted in changes in animals and plants under domestication, then what does Darwin say is the logical step that you need to make in order to agree that the natural selection has resulted in changes in animals and plants in nature? (in other words, how does Darwin use artificial selection to explain natural selection).
"As man can produce, and certainly has produced, a great result by his methodical and unconscious means of selection, what may not natural selection effect? Man can act only on external and visible characters: Nature, if I may be allowed to personify the natural preservation or survival of the fittest, cares nothing for appearances, except in so far as they are useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good; Nature only for that of the being which she tends. Every selected character is fully exercised by her, as is implied by the fact of their selection. Man...feeds a long and a short-beaked pigeon on the same food...he exposes sheep with long and short wool to the same climate; does not allow the most vigorous males to struggle for the females; he does not rigidly destroy all inferior animals, but protects during each varying season, as far as lies in his power, all his productions. He often begins his selection by some half-monstrous form, or at least by some modification prominent enough to catch the eye or to be plainly useful to him. Under nature, the slightest differences of structure or constitution may well turn the nicely-balanced scale in the struggle for life, and so be preserved. How fleeting are the wishes and efforts of man! How short his time, and consequently how poor will be his results, compared with those accumulated by Nature during whole geological periods! Can we wonder, then, that Nature's productions should be far "truer" in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly bear the stamp of far higher workmanship?"
"No one supposes that all the individuals of the same species are cast in the same actual mould. These individual differences are of the highest importance for us, for they are often inherited, as must be familiar to every one; and they thus afford materials for natural selection to act on and accumulate, in the same manner as man accumulates in any given direction individual differences in his domesticated productions."
"Owing to this struggle, variations...if they be in any degree [helpful] to the individuals of a species...will tend to the preservation of such individuals, and will generally be inherited by the offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals...born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term natural selection, in order to mark its relation to man's power of selection."
"A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase.
There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair."
6. Say one cool thing that you learned from each of the other eight mad cow disease presentations (except your own group’s presentation). Remember: I have them on film, so I KNOW what they said!!
7. Are viruses alive? Either can be argued, but justify your answer with specific details concerning the make up of viruses and the make up of other living organisms. You will want to be clear about your definition of living things.
8. In the 15th to 17th century, many native South Americans became sick and died from diseases brought over from Europe by the explorers/conquistadores. Jared Diamond, in his book “Guns Germs and Steel,” argues that zoonoses (animal derived diseases – see the Weiss article from Feb 18) were more likely to be passed FROM Europeans TO native South Americans rather than the reverse. Using Weiss’s article as a source (and your knowledge of how immune systems work), do you agree with Jared Diamond? If so, why? And if not, why not? Be specific!!
Note: You do not need to read “Guns Germs and Steel” to answer this question (although it is a great book, and we will read excerpts later in the semester)!
HINT: think about the common sources of zoonoses and the conditions under which they are likely to spread to humans
6 CO2 + 12 H2O + energy (from the sun) C6H12O6 + 6 H2O + 6 O2
6 CO2 + + 6 H2O + energy (ATP) C6H12O6 + 6 O2
cellular respiration is (essentially)
photosynthesis in reverse !!