Q: A population of birds has two alleles for feather color: B (black) and b (brown). If the frequency of allele B is 0.7 and the population is in Hardy-Weinberg equilibrium, what is the expected frequency of heterozygous individuals?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

Which of the following best describes the main contribution of Alfred Russel Wallace to the theory of evolution?

Accepted Answer

He independently conceived the theory of natural selection and prompted Darwin to publish his own work.

Question 2

Which equation represents the Hardy-Weinberg equilibrium for a gene with two alleles, A and a, with frequencies $$p$$ and $$q$$?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 3

A population of birds has two alleles for feather color: B (black) and b (brown). If the frequency of allele B is 0.7 and the population is in Hardy-Weinberg equilibrium, what is the expected frequency of heterozygous individuals?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Question 4

Which of the following is an example of stabilizing selection?

Accepted Answer

Human birth weight, where both very low and very high weights have higher mortality.

Question 5

Which of the following is NOT a postzygotic reproductive barrier?

Accepted Answer

Temporal isolation

Question 6

Which scenario best illustrates the concept of ecological (habitat) isolation?

Accepted Answer

Two species of frogs live in the same region but breed in different types of water bodies.

Question 7

Which of the following best describes the role of a keystone species in a community, as demonstrated by Dr. Robert Paine’s experiments?

Accepted Answer

Its removal causes a dramatic shift in community structure and loss of biodiversity.

Question 8

Which of the following equations best represents exponential population growth?

Accepted Answer

$$\frac{dN}{dt} = rN$$

Question 9

A population of rabbits grows according to the logistic growth model. If the carrying capacity ($$K) is 500 $$and the current population size ($$N) is 250$$, which equation gives the rate of population growth?

Accepted Answer

$$\frac{dN}{dt} = rN \left(1 - \frac{N}{K}\right)$$

Question 10

Which of the following is a real-world example of biomagnification?

Accepted Answer

Increasing concentrations of DDT in predatory birds at the top of the food chain.

Question 11

Which of the following best explains why genetic drift has a greater effect in small populations?

Accepted Answer

Random fluctuations in allele frequencies are more pronounced due to fewer individuals.

Question 12

Which of the following is an example of mutualism?

Accepted Answer

Bees pollinating flowers while feeding on nectar.

Question 13

Which of the following is a density-dependent factor that can regulate population size?

Accepted Answer

Competition for food resources

Question 14

Which of the following best describes the Biological Species Concept (BSC)?

Accepted Answer

A species is a group of interbreeding natural populations that are reproductively isolated from other such groups.

Question 15

Which of the following scenarios best illustrates disruptive selection?

Accepted Answer

A population of finches where both small and large beak sizes are favored over intermediate sizes.

Question 16

Which of the following is an example of allopatric speciation?

Accepted Answer

A river divides a population of squirrels, leading to the evolution of two distinct species.

Question 17

Which of the following best describes the effect of competitive exclusion?

Accepted Answer

Two species competing for the same limiting resource cannot coexist indefinitely.

Question 18

Which of the following is a prediction of the Hardy-Weinberg principle?

Accepted Answer

Allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary forces.

Question 19

Which of the following best explains why the biomass of organisms decreases at higher trophic levels in a food pyramid?

Accepted Answer

Energy is lost as heat at each trophic transfer, resulting in less biomass available to higher trophic levels.

Question 20

Which of the following is a real-world example of natural selection documented by Peter and Rosemary Grant?

Accepted Answer

Changes in beak size of Galápagos finches in response to drought conditions.

Evolution and Ecology: Community and Population Biology Study Guide

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