9 Mar 2018

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

haploid genotypes of all the gametes produced by a diploid individual
ABO blood type conferred by an individual gamete
genotype of either the paternal or maternal chromosomal complement
multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.
Is reduced by sexual reproduction.
Is increased by crossing-over during meiosis.
Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates
it eliminates all haplotypes from the population
it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time
the two loci (or, more specifically, their protein products) do not interact
the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.
In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.
Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.
All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium
low frequency and low linkage disequilibrium
low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.



8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.



9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over
recombination creating novel genotypes that can resist infection by parasites
mutation load is reduced by novel adaptive mutations
the ability of sex to fix multiple

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Collen Von
Collen VonLv2
9 Mar 2018

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