BIOLOGY 171 Study Guide - Midterm Guide: Speciation, Polyploid, Species

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tanwoodchuck448

10 Apr 2014

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Lecture 19: compare and contrast all the evolutionary processes in terms of effects on genetic variation and allele frequencies, natural selection, sexual selection, genetic drift, gene flow, mutation, only evolutionary processes can change allele frequencies, explain the hardy weinberg principle in your own words, states that after one generation of random mating, genotype frequencies for two alleles at one gene will be: p2+2pq+q2=1, genotype and allele frequencies will remain constant in succeeding generations as long as certain assumptions are met, explain the assumptions of hardy weinberg equilibrium, population size is very large no genetic drift, population is closed no gene flow, no mutations occurring at the gene under study, mating is random no sexual selection, no inbreeding, all genotypes in population have equal chance of surviving and reproducing no selection, apply the hwe model to make predictions about allele and genotype frequencies in a population, p (freq. of a) = aa + aa/2, q (freq. of a)= aa + aa/2.

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I need this in 15 min!Please help!!!1

A gene in a population of sexually reproducing organisms with the following genotype frequencies is at Hardy-Weinberg Equilibrium: BB 100, Bb 800, bb 100

A) true B)false C) can not be determined

Which of the following evolutionary forces would be the best explanation for the genotype frequencies in the population in the above question?

A) genetic drift B) there are no evolutionary forces acting on this gene population C)assortive mating D) Overdominance E)Directional selection

If a population is at Hardy-Weinberg equilibrium, which of the following allele frequencies would yield the smallest number of heterozygotes? A)

A=0.25, B=0.75 B) A=0.75, B=0.25

C)A=0.50, B=0.50

D)A=0.10, B=0.90

Fixation occurs when one allele becomes the only allele for a gene in a population, meaning that all other alleles for that gene have been lost. True or false

azurepug898

Q1. What are alleles?Different forms of the same gene.Different genes.The different characteristics of an organism.Genes found only in humans.Q2. If you add up the frequency of homozygotes + the frequency of heterozygotes for one gene (i.e. at one locus) in a population, what number do you get?Q3. People who are heterozygous for the sickle-cell allele:Are susceptible to malaria but not sickle-cell anemia.Are susceptible to sickle-cell anemia but not malaria.Are not susceptible to either sickle-cell anemia or malaria.Are susceptible to both sickle-cecell anemia and malaria.Q4. In the case study in this lab, which genotype is represented by "2pq" in the Hardy-Weinberg equation?Homozygous HbAHomozygous HbSHeterozygous HbA/HbSNo specific genotypeQ5. Suppose that, in an isolated village, the proportion of individuals that have sickle-cell anemia is 0.1 (or 1 of every 10 people). What proportion of the population should be sickle-cell carriers, according to Hardy-Weinberg expectations?Q6. When you simulated the elimination of malaria at the beginning of the lab, once the allele frequencies stabilized, what was the frequency of the HbA allele?Q7. When you investigated regional differences, what was the frequency (over many generations) of the HbS allele in the village in the "slightly wet" part of Africa?Q8. What is the number of deaths due to sickle-cell anemia in a region without mosquitoes expected to be?Very lowVery highModerateRelated to the frequency of malaria allelesQ9. As long as there are multiple alleles of a gene in a population, why will the frequencies of the alleles always change over time?Because natural selection changes all allele frequencies in populations over time.Because genetic drift causes random fluctuations of allele frequencies in populations.Because diseases will eliminate some of the alleles, generating fluctuations in their frequencies.Because allele frequencies fluctuate before the alleles eventually become fixed.Q10. Imagine a huge population with a gene that has ten functionally equivalent, neutral alleles. A small but genetically representative group of individuals from the big population is transported to an island, forming a small population. Which of the statements below best describes what will likely happen over time, and why?Because natural selection doesn't act on neutral alleles, the frequencies in the two populations should remain the same over time.Genetic drift will cause one allele to first become fixed in the island population, and later to become fixed in the original, large population.Genetic drift will result in the allele frequencies of the two populations diverging over time, with alleles being lost sooner in the island population.The allele frequencies of the two populations will change similarly due to a combination of genetic drift natural selection.

indigosnake469

1. A) Explain how changes in the environment drive evolutionary change. B) Provide and explain an example

2. A) Explain how the Hardy-Weinberg equation allows us to find evidence of evolution. B) Could processes other than Natural Selection result in deviation from the Hardy-Weinberg equilibrium? List and explain each one: C) define what the process is and D) the effect it has on the allele frequency.

3. A gene that is responsible for multiple traits (pleiotropy), for example the same allele causes sickle-cell anemia and provides resistance to malaria. Would a gene that controls these two traits respond equally to natural selection favoring malaria resistance as a non-pleitropic gene that only controls malaria resistance? Explain your answer.

4. A) Explain how lack of genetic variation limits evolution and provide an example. B) Explain how epistasis limits evolution and provide an example

Questions 5-6 are based on the following:

Letâs say you are studying a population of Japanese four oâclock plants. In these plants, the allele for red color flower shows incomplete dominance over the allele for white flowers. This is very convenient for this experiment because you can distinguish the heterozygous (pink flowers) from the homozygous dominant (red flowers). For your experiment, you produced a large number of plants, 25% had red flowers, 25% had white flowers and 50% had pink flowers. You transplanted them into different habitats and left some in the lab (using the same proportions in all the habitats). You waited a few years, while plants reproduce for a few generations and then you go back and resample the populations youâve transplanted.

5. In the lab you ensured that all individuals receive all requirements to grow and reproduce and mate randomly. A) What do you expect the distribution of the phenotypes after a few generations breeding in the lab? B) Is the lab population in Hardy-Weinberg equilibrium? Yes/No, explain

6. In habitat A, you find that you only have red flowering plants and white flowering plants but there are no pink flowering plants. A) Is the population in habitat A in Hardy-Weinberg equilibrium? Yes/No, explain. B) Which one(s) of the five agents of evolutionary change could be responsible for these results? Explain. C) What type(s) of selection (stabilizing, disruptive, directional, oscillating, etc...) could be responsible for the results in habitat A? Explain

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BIOLOGY 171 Study Guide - Midterm Guide: Speciation, Polyploid, Species

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