Question 1

Which of the following best describes the main effect of stabilizing selection on a population's trait distribution?

Accepted Answer

It compresses genetic variation by reducing the frequency of both extremes, increasing the proportion of intermediate phenotypes.

Question 2

A population of birds experiences a sudden change in environment where only birds with very large or very small beaks can access food, while those with intermediate beak sizes struggle to survive. Which mode of selection is most likely occurring?

Accepted Answer

Disruptive selection

Question 3

Which of the following is NOT an assumption of Hardy-Weinberg equilibrium?

Accepted Answer

Non-random mating

Question 4

If the frequency of allele A ($p$) in a population is $0.7$, what is the expected frequency of heterozygotes ($2pq$) under Hardy-Weinberg equilibrium?

Accepted Answer

$0.42$

Question 5

A researcher observes that the genotype frequencies in a population deviate significantly from those expected under Hardy-Weinberg equilibrium. Which of the following could explain this deviation?

Accepted Answer

There is gene flow from another population.

Question 6

Which of the following best defines 'adaptation' in an evolutionary context?

Accepted Answer

A heritable trait that increases an individual's fitness in a particular environment.

Question 7

In a population, the observed genotype frequencies for a gene with two alleles (A and a) are: $AA = 0.36$, $Aa = 0.48$, $aa = 0.16$. What is the frequency of allele a ($q$)?

Accepted Answer

$0.60$

Question 8

Which scenario is an example of directional selection?

Accepted Answer

A population of bacteria where only those resistant to antibiotics survive and reproduce.

Question 9

Which of the following statements about natural selection is TRUE?

Accepted Answer

Natural selection results in the increase of traits that enhance fitness in a given environment.

Question 10

A population is in Hardy-Weinberg equilibrium for a gene with two alleles, B and b. If the frequency of genotype $bb$ is $0.09$, what is the frequency of allele B ($p$)?

Accepted Answer

$0.7$

Question 11

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype is the genetic makeup of an organism, while phenotype is the observable traits resulting from the genotype and environment.

Question 12

Which of the following is a correct step in testing for Hardy-Weinberg equilibrium in a real population?

Accepted Answer

Calculate the observed genotype frequencies from the sample.

Question 13

A population of fish is exposed to a new pollutant that kills individuals with a certain genotype. Over several generations, the frequency of that genotype decreases. This is an example of:

Accepted Answer

Natural selection

Question 14

Which of the following would violate the assumptions of Hardy-Weinberg equilibrium?

Accepted Answer

Small population size leading to genetic drift

Question 15

In a population, the frequency of allele D is $0.4$. What is the expected frequency of homozygous dominant individuals ($DD$) under Hardy-Weinberg equilibrium?

Accepted Answer

$0.16$

Question 16

Which of the following best explains why genetic variation is important for evolution by natural selection?

Accepted Answer

It allows populations to adapt to changing environments by providing raw material for selection.

Question 17

A population of rabbits has the following genotype frequencies: $RR = 0.25$, $Rr = 0.50$, $rr = 0.25$. If the population is in Hardy-Weinberg equilibrium, what is the frequency of allele r?

Accepted Answer

$0.50$

Question 18

Which of the following is an example of gene flow?

Accepted Answer

Individuals from one population migrate and breed with another population, introducing new alleles.

Question 19

Which of the following statements about evolutionary processes is correct?

Accepted Answer

Natural selection is the only evolutionary process that results in adaptation.

Question 20

A scientist wants to determine if a population is evolving at a particular gene locus. Which of the following would provide the strongest evidence that evolution is occurring?

Accepted Answer

Observed genotype frequencies differ significantly from those expected under Hardy-Weinberg equilibrium.

Evolutionary Processes and Hardy-Weinberg Equilibrium: Study Notes for General Biology

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