Ls15 midterm review guide PDF

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LS15 midterm review guide...

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LS15 Midterm Review Guide (bruincast on CCLE): 6 short answer (cannot write on back of page, must fit in the space provided), 20 multiple choice When explaining, use examples (experiments or case studies) to strengthen your argument.

1. What is scientific thinking? What is it for and how does it work? (E.g. How would you figure out _________?) “here is my hypothesis, here’s my prediction, experiment, how I interpret it…” Scientific thinking is making an observation, proposing a hypothesis, formulating a prediction, conducting a crucial experiment, and coming up with a conclusion/analysis. Scientific  thinking illuminates situations in which we should change what we think. 2. How does a hypothesis differ from a theory or a prediction? Hypothesis is a proposed explanation  of an observation you make. Prediction comes from hypothesis. Theory is something that everyone seems to believe is true and much evidence has proved it to be true. Hypothesis is an assumption made before any research has been completed for the sake of testing. 3. What does it mean to control an experiment? To control an experiment means the conductor of the experiment changes only one variable between subjects to isolate results he or she is testing for. We use the concept of control in scientific thinking. When we talk about controlled or non-controlled experiments, it doesn’t define the usefulness of the experiment. The real question is HOW WELL the experiment was controlled. (e.g. report about sleep, comparing people’s sleep. Some lumped in groups of two groups: less than 7 hours and more than 8 hours. They looked and figured out that people who got less sleep were more prone to sickness. This was not a well-controlled experiment because the two groups did not only differ in the one thing you are interested in.) The  accuracy of conclusions depends on the level of control the experiment has reached. 4. Compare and contrast superstition, anecdotal observations, and pseudoscience. Be able to give examples. Superstition is a widely held unjustifiable belief in supernatural causation. Anecdotal observation is evidence collected based on personal testimony and observations. We are overly biased by observations that are not based on careful study and/or not representative of the norm. Pseudoscience is a collection of beliefs or practices mistakenly regarded as being based on scientific method. Pseudoscience and anecdotal observations can be almost unbearably appealing, but should not influence our beliefs. An example of a superstition would be knocking on wood in order to bring good luck and ward off bad fortune. An example of an anecdotal observation would be if I assumed drinking Emergen-C Vitamin C drinks reduces my chances of getting sick, even though I have not conducted an experiment to prove it to be true. An example of pseudoscience is “9 out of 10 doctors recommend brand X.” You must be alert and ask questions such as

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“How do you know what you claim to know?” Another example is: “Vaccines cause autism.” With more and more observations that support a hypothesis, do you eventually prove it to be true? If not, what happens? No, you can only prove a hypothesis to be false but never true. A single piece of evidence that contradicts a hypothesis is sufficient for us to reject it. You can never conclude that a hypothesis is true because you are at risk of future evidence showing up that contradicts it. You may say that as more and more evidence and experiments come out, you can have more and more confidence  that the hypothesis is reliable and/or true. Any hypothesis must be rejected if there is a counterexample that disproves it. What is evolution? How can it occur? Provide an example. Evolution is the gradual change in allele frequency within a population (e.g. birth weight in babies, babies who are too heavy or too light, then the fitness goes down. We are losing alleles on the very left and very right of the distribution (stabilizing selection, mean value does not change but the alleles that influence really low or really high decrease in frequency). Turkey breasts - directional selection. Fur color - camouflage and adaptation.) Evolution can occur through four ways: Mutation (random change in a single allele), Genetic Drift (non-directed change in the frequency of an allele within a population, either bottleneck or founders effect), Gene Flow/Migration (where same species from multiple populations breed together to stabilize allele frequency), and Natural selection (three conditions: variability, heritability, and differential reproductive success, there are three kinds: stabilizing, directional, and disruptive selection, as well as artificial and sexual selection) What is Natural Selection? How does it work? Natural selection is one of four mechanisms by which evolution (change in alleles in a population) can occur under three conditions: variability, heritability, and reproduction success. What ideas and information influenced Darwin? Galapagos, one species of finch, go to another island in Ecuador. He realized that there was change occurring. Darwin saw giant armadillos that shared a similar--but bigger--anatomy with the current armadillo species. a. Two observations: finch variation on the mainland (Ecuador) near Galapagos, 1 species of finch and then you go 600 miles off the coast and now you got 13-14 islands and every one seems to have its own species. He thought, maybe y’all used to be the same population. Darwin imagined that the island species might be

all species modified from one original mainland species. The second observation was the giant armadillo (glyptodont) fossil that was similar the armadillos he saw in Argentina. 9. Why does artificial selection almost always work? (need to have 3 things of natural selection) You are providing differential reproductive success. Making very tiny horses by selecting the smallest 20% of the smallest 20% of the smallest 20% etc… It

always works because it satisfies the 3 conditions of natural selection. It won't work for all things, such as languages humans speak. 10. How is genetic drift related to Mendel’s first law? Make sure to be able to concisely and precisely define the terms in the question and apply it. Mendel’s first law of segregation said that, you have parents who have diploids and it is random which chromosome they have gets put into gamete, so where does the random change of allele frequency come into his law of segregation. Genetic drift is random change in allele frequency and its one of the 4 mechanisms by which evolution can occur. Mendel’s first law of segregation states that parents have two copies of each chromosome but they produce gametes that only have one copy of each chromosome, and it is random which chromosome they have gets put into the gamete. At fertilization, we re-establish diploid numbers. 11. Sexual selection. What is it and why does it lead to tradeoffs? Use  an example. It is a special type of natural selection (3 conditions satisfied). The differential reproduction success is decided by one or the other sex. The tradeoff could be a trait that attracts the opposite sex more but it decreases your chance of survivial. (e.g. male peacocks and their feathers attract females more but it makes them more prone to predators) 12. Reaction Norms. What are they and how does the slope describe the relationship between genotypes and phenotypes? DESCRIBES INTERACTION BETWEEN NATURE VS. NURTURE. A reaction norm shows the set of all phenotypic expressions possible for a given genotype across all possible environmental conditions. A steeper slope means phenotypes differ a lot for a single genotype when it is raised in different environments. A flatter slope means the phenotype is always the same for a single genotype, regardless of the environmental condition. (USC example: The x-axis is environmental variable, the y-axis is phenotype. If that norm of reaction was flat, then we could say, for that given genotype, it does not matter what environment you are in.) When they examine reaction norms, they will change the y-intercepts to see which one has an outcome. See for a given genotype, all the different types of phenotypes you can get. 13. What is evolutionary fitness? Why does evolution lead to selfish behaviors at the expense of those best for the species? (Discussion Section notes) Relative reproductive success compared to other individuals in a population in a specific environment. Evolution leads to selfish behaviors because you will try to pass on your own genes to the best of your ability. 14. Using an example, explain what evolutionary mismatch is. Evolved traits that were once advantageous but became maladaptive due to changes in the environment. Most  important concepts in evolutionary biology. In the world we evolved in, our stress response was commonly about things with extremely high risk. Our cortisol is designed to make our bodies really good at fight or flight response. Because we learn to deal with

stress, we expose ourselves to chronic fight or flight cortisol battles that have a lot of bad effects on us. An example is if you are anxious because you are late to class nowadays. Back then, you would only have an anxious fight-or-flight response if it was a life-threatening situation, but it is not necessary (even maladaptive) now because of the obvious change in environment. 15. How do dominant and recessive alleles differ? The full motive inheritance of eye color is not a single gene with two alleles. The real situation is more complex than this. If they have BB or Bb they still have brown eyes. The dominant allele masks the effect of the recessive. E.g. one allele codes for a version of lactose that doesn't work (does not break down milk sugar) but the other allele works. But if you have one copy that does work, then the individual is fine, because the one copy that works covers up the one that doesn't. 16. What is Mendel’s first law (of segregation)? Why do offspring look like their parents? There is no perfect resemblance because there are two parents who both pass their genes to the offspring. Practice explaining the law and explain why offsprings do not look exactly like their parents. 17. Why don't full siblings look identical to each other? In other words, why are their phenotypes not identical? (how you sound, behavior, physical capabilities, etc.) If you grew up in a family of many siblings, and some pairs resemble each other a lot and others not so much. Explain. Which of your parents' two gene copies you end up with is chosen at random because of Mendel’s law of segregation. You and your siblings’ double gene copies are different. Environmental factors can also alter phenotypes (steep norm of reaction). 18. How is Mendel’s law of segregation relevant to gamete production? 19. Mendel studied peas. To what extent does that limit his application of his discovery of other organisms? Experiments are expensive. For example, you can use animals in experiments and apply it to humans. Mendel studies heritability for humans, turkeys, dogs, horses, etc.. but he never conducted the experiments with those. Mendel applied study results to humans because peas share the same characteristics: sexual reproduction, gametes are haploid, peas are diploid. 20. How do you predict offspring genotypes for sex-linked traits? Be able to say “hey, you have some white-eyed male flies crossed with red-eyed female flies,” sex-linked trait, white eyes is recessive. Therefore, the gene we’re talking about is on X chromosome. Be able to make a punnett square. ALL SEX-LINKED TRAITS ARE LINKED TO X CHROMOSOME. 21. In a pedigree, figure out individual genotypes and how its traits is passed down (dominant or recessive, sex-linked or autosomal?) KHAN ACADEMY 22. How does sex determination among different species vary? Humans: Males have XY, Females have XX. Birds: Males have XX, females have XY. Turtles all have same sex

chromosomes, sex is determined by environment. Ants, bees, wasps, sex determination is done through HAPLODIPLOIDY: Females are diploid, Males are haploid. (1 full set of chromosomes or two) 23. Does having a particular genotype ensure you will have a particular phenotype? No, a genotype can code for many phenotypes, PLEIOTROPY . In addition, not all norms of reaction are flat. Example: one genotype can lead to death or happy life. 24. Using blood types, explain how multiple alleles can come together in a population in different phenotypes. You inherit one from mom and one from dad. But there is a whole range in a population as a whole. Understand Mendel’s law of segregation and how heritability works. a. In the ABO blood groups, you can either have Blood types A, B, AB, or O. O is recessive, while A and B are dominant. Mendel’s law of segregation states that each gamete can only receive one allele and, at fertilization, the two alleles from each parent (selected at random) will join together to give you a full set of chromosomes. A can be expressed by AA or AO. B can be expressed by BB or BO. AB can be expressed by AB. O can be expressed by OO. AB is an example of codominance in alleles. 25. What is fitness and inclusive fitness and how does belding’s ground squirrels help us understand them? Fitness is your relative reproductive success. Inclusive fitness is really how well the alleles you carry do relative to the alleles that other people carry. Some of your alleles can be passed on not by your own reproduction but by your siblings passing them on, so if you help them, you can have high fitness. The calling of the squirrel is a suicide act but lets her relatives survive to reproduce. A female does something that reduces her own direct reproductive success, but it causes her indirect reproductive success to be really high by allowing lots of her relatives to survive. 26. What does Hamilton’s rule help us understand? Why we see kindness to kin. Why we help those who are closely related to us? Doing something that comes as a cost to you but benefits someone else. Hamilton’s rule says everytime B*R-C>0, natural selection is going to favor that behavior 27. Describe the evidence in support of Hamilton’s rule. The closer related they are, higher probability acts of kindness between those individuals occur. If we have extra kidney, we don't give to someone who actually needs it, but we do for our relatives. Be able to give at least five different pieces of evidence in support of Hamilton’s rule. 28. How do you calculate the coefficient of relatedness (r)? Why is that important? “r” is important because in order to know what Hamilton’s rule is going to tell you about something, you must know what r is. R  is the probability that the allele in one individual is also in the other, therefore when you are maximizing your fitness, you want to help your own alleles be represented next generation, so you're more likely to be kind to the person who is likely to share the same allele with you.

29. Unexpected cooperation and conflict. When and why do we see that? We talked about kindness in three separate distinctions. “Maladaptive Behavior” “MUTUAL BENEFIT” “RECIPROCAL ALTRUISM” “EVOLUTIONARY MISMATCH” real answer: “WE DON’T”, because we have a complete theory of kindness. If you see something that looks like kindness, it is selfishness towards a kin. OR it is kindness towards an unrelated individual who is likely to pay them back. IT IS NEVER UNEXPECTED. 30. Reciprocal altruism. Under what conditions should we see it? 31. What are rules of thumb and how are they relevant to evolution and behavior? Rules of thumb are instincts that are a reflection of maladaptive behavior that almost always serve an individual well. Squirrel goes “I am an old female, I have lots of relatives” and acts accordingly, she does not calculate coefficient of relatedness. Rule of thumb says natural selection can cause individuals to behave in certain ways to cause an outcome 32. Describe three strategies to increasing cooperation among unrelated individuals. 33. What is the Ultimatum Game? How is it related to reciprocal altruism? Economists thought everyone will maximize utility, but that is not true. In reality, we propose the “25 for me, 15 for you” because they think that the 35-5 will be rejected. The ultimatum game reveals that people make generous offers and people who were going to reject the stingy offer accepts it from a machine, it violates sense of justice. The ultimatum game generates testable predictions. a. One of the conditions of reciprocal altruism is that we need to keep tabs on “cheaters” and keep up good reputation. From a biological perspective, people would likely turn down free money if the proposer consciously proposed the stingy offer in order to “punish them.” However, if the proposer’s offer was decided by a random computer generator, then the receivers would most likely accept the offer. If Jay phelan put up pictures on Kerckhoff building of us with our names on it, and showing how stingy or generous we are, then we are more likely to change our offer as the proposer from a stingy one to a more generous one. This is because we want to be seen as more generous to keep up a good reputation. The results are not how economists, who thought people only cared about maximizing utility, expected. 34. What are STR Loci and how do they differ? Use this in a description of how DNA fingerprinting works. a. STR loci are units of 4 to 5 nucleotides in a DNA strand. They differ in the number of times those units repeat on the DNA. DNA fingerprinting works in criminology by matching the STR loci of individuals to that of a specific crime scene. Usually, we need to find 13 STRs to accurately conclude who the perpetrator is. If the number of STRs identified is not high, then there would be

multiple matches, but they could not have all committed the crime. What that means is if there were 10 alleles in a population, it would be 1/10 times 1/10, or 1/100. In the US, that would be approximately 3 million people who match. The DNA fragment containing each STR is amplified using PCR, which is polymerase chain reaction, using heat to break them apart and then pairing them with new nucleotides to produce billions of copies of that DNA strand. The fragments are separated by size using gel electrophoresis. Small bands move fast and large bands move slow. 35. Although the science-underlying DNA fingerprinting is universally accepted, why are there still reasonable criticism about its use. a. Overlap of STRs. Alleles that have small differences in size (number of STR) between them, they can look very similar. b. How many STRs should they compare? c. Can the jury understand the likelihood of a match? d. Human error. 30% false eyewitness....