Bsci 370 Homework 4



Download 11.24 Kb.
Date conversion06.02.2018
Size11.24 Kb.
BSCI 370 - Homework 4

1) Imagine you are grabbing two socks, one from each of two different drawers (A and B). In each drawer there are four socks, two red and two white. What is the probability that you get a red sock from A and a red sock from B? What is the probability that you pick a red sock from A and a red or white sock from B? How do these probabilities change if drawer B has 1 red and 3 white? What drawer B has 1 red, 2 white, and one yellow?
Now imagine there is only one drawer with four socks (2 red and 2 white). If you pick each sock one a time, what is the probability you will get two red socks?
3) If you are told a population is in Hardy-Weinberg equilibrium, and that the recessive genotype frequency is 0.06, what is the frequency of heterozygotes? Show your work.
4) In a species of bird, individuals with genotype MM are susceptible to avian malaria and Mm birds are resistant to avian malaria. The recessive birds, mm, are resistant to avian malaria but vulnerable to avian pox. Selection imposed by each disease is equal. Assuming the population is now in Hardy Weinberg equilibrium with both M and m alleles present in the population, and the population having never been exposed to either disease.
A. How will the allele frequencies change if at all, when the population is exposed to avian malaria:

a) M will increase


b) m will increase
c) The allele frequencies will not change
d) It is impossible to predict
B. How will the allele frequencies change if at all, when the population is exposed to avian pox:

a) M will increase

b) m will increase
c) The allele frequencies will not change
d) It is impossible to predict

C). How will the allele frequencies change if at all, when the population is exposed to BOTH avian malaria and avian pox:


a) M will increase
b) m will increase
c) The allele frequencies will not change
d) It is impossible to predict
5) A TRUE STORY: Clover is a plant that is found in many fields in Europe.

-There is a genetic polymorphism present in clover in Europe associated with the release of cyanide from the leaf tissue, when the leaf tissue is damaged.

-Individuals of type AA release lots of cyanide when the leaf is damaged, Aa individuals an intermediate amount (incomplete dominance) and aa individuals NO cyanide.

-The release of cyanide when the leaf is damaged prevents or reduces other leaves of the plant from being eaten by animals, such as slugs, cattle, etc.

-The release of cyanide also results in a nonfunctional leaf. For example, AA individuals will be avoided by leaf eating animals, because the animals leave the plant alone once the animal has tasted the cyanide, but the leaf that was partially chewed will eventually die.

-FROST damage can also lead to the release of cyanide, resulting in the destruction of the leaf.

-Individuals that are AA are most prone to frost damage, Aa less so and aa individuals not at all, due to the release of cyanide into the leaf tissue. In other words:
AA is more resistant than Aa, which is in turn more resistant than aa in terms of resistance to animals

eating it But

AA has more leaf damage following frost than Aa, which in turn has more leaf damage than aa

following frost

Use this information to address the following problems:

A. The following survivorship of genotypes was observed in a population of Clover on the Coast of England, relatively mild climate with little frost. Remember the presence of A confers increasing resistance to animals eating leaves through the expression of cyanide, but also increases the amount of frost damage.
Coast of England Genotype

AA Aa aa
# individuals before selection 100 100 100


# individuals after selection 80 40 0
However the following survivorship was observed for a population of Clover at an elevation of 8000 ft in the Swiss Alps:
Swiss Alps Genotype
AA Aa aa
# individuals before selection 100 100 100
# individuals after selection 25 50 5

With respect to the above data, do the following:




  1. Calculate the fitness of each genotype at each location

Fitness of AA Aa aa

Coast of England:

Swiss Alps:

B. Calculate the equilibrium frequency of a in the Swiss population

First calculate the ā€œsā€ or the selection coefficients for this population, then provide the


equilibrium frequency of the a allele.




The database is protected by copyright ©hestories.info 2017
send message

    Main page