Q: In a population, the frequency of allele $$A is$$ $$p = 0.7$$ and the frequency of allele $$a is$$ $$q = 0.3. $$According to the Hardy-Weinberg equation, what is the expected frequency of heterozygotes ($$Aa$$)? $$\text{Hardy-Weinberg: } p^2$ + 2pq + q^2$ = 1$$

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

Question 1

Which of the following best describes the main mechanism by which natural selection leads to evolution in a population?

Accepted Answer

Individuals with favorable phenotypes survive and reproduce more successfully, increasing the frequency of those traits in the next generation.

Question 2

A population of insects is exposed to a new pesticide. After several generations, most individuals are resistant to the pesticide. Which process best explains this change?

Accepted Answer

Natural selection, where individuals with resistance alleles survive and reproduce more than susceptible individuals.

Question 3

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Accepted Answer

Small population size

Question 4

In a population, the frequency of allele $$A is$$ $$p = 0.7$$ and the frequency of allele $$a is$$ $$q = 0.3. $$According to the Hardy-Weinberg equation, what is the expected frequency of heterozygotes ($$Aa$$)?

$$	ext{Hardy-Weinberg: } p^2$ + 2pq + q^2$ = 1$$

Accepted Answer

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

Question 5

Which of the following is an example of genetic drift?

Accepted Answer

A hurricane randomly kills most of a small bird population, leaving only a few survivors to repopulate the area.

Question 6

Which statement best distinguishes homologous structures from analogous structures?

Accepted Answer

Homologous structures are inherited from a common ancestor, while analogous structures arise independently due to similar selective pressures.

Question 7

Which of the following provides the strongest evidence for the common ancestry of all eukaryotes?

Accepted Answer

Presence of membrane-bound organelles, linear chromosomes, and genes containing introns in all eukaryotes.

Question 8

A population of fish is split by the formation of a new river, and over time, the two groups diverge genetically and can no longer interbreed. This is an example of:

Accepted Answer

Allopatric speciation

Question 9

Which of the following is a postzygotic reproductive barrier?

Accepted Answer

Hybrid offspring are sterile and cannot produce their own offspring.

Question 10

Which process is most likely responsible for the rapid emergence of many new species following a mass extinction event?

Accepted Answer

Adaptive radiation

Question 11

Which of the following best explains why antibiotic resistance in bacteria is considered an example of ongoing evolution?

Accepted Answer

Bacteria with mutations that confer resistance survive and reproduce in the presence of antibiotics, increasing the frequency of resistance alleles.

Question 12

Which of the following is a shared derived character (synapomorphy) useful for constructing a phylogenetic tree?

Accepted Answer

A trait that is present in an ancestor and all its descendants, but not in more distant relatives.

Question 13

Which of the following is a key assumption of the RNA world hypothesis for the origin of life?

Accepted Answer

RNA molecules were capable of self-replication and catalysis before the evolution of DNA and proteins.

Question 14

A population of lizards has two color morphs: green and brown. In a forest environment, green lizards are more likely to survive, but in a desert environment, brown lizards have higher survival. What does this scenario illustrate about natural selection?

Accepted Answer

The fitness of a phenotype depends on the environment, and different environments can favor different traits.

Question 15

Which of the following is an example of artificial selection?

Accepted Answer

Humans breeding cows to produce more milk over generations.

Question 16

Which of the following best describes the founder effect?

Accepted Answer

A small group of individuals establishes a new population, leading to a change in allele frequencies compared to the original population.

Question 17

Which of the following is a reason why natural selection cannot produce perfect organisms?

Accepted Answer

Evolution is limited by historical constraints and existing genetic variation.

Question 18

Which of the following is a real-world example of gene flow?

Accepted Answer

Pollen from one population of wildflowers fertilizes plants in a neighboring population, introducing new alleles.

Question 19

Which of the following statements about the fossil record is accurate?

Accepted Answer

The fossil record provides detailed evidence of evolutionary change, but is incomplete due to the rarity of fossilization.

Question 20

Which of the following best describes punctuated equilibrium?

Accepted Answer

Long periods of little evolutionary change interrupted by brief periods of rapid speciation.

Study Guidance for Unit 7: Natural Selection and Evolutionary Biology

Study Guide - Practice Questions

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