Chapter 23 Quiz
Name:
Hour:
Fill in the blank with the best answer: Each is worth 2 points (10 Total)
1) _______________ is the accumulation of heritable changes within populations over
time.
Answer: Evolution
2) The genetic expression of traits (e.g., “homozygous recessive”) is called the
organism’s _______.
Answer: genotype
3) ___________ occurs when different phenotypes of the same species survive and
reproduce at different frequencies because some are better adapted to a particular
environment .
Answer: natural selection
4) ________________can be brought about either by a severe reduction in population
size, known as a population bottleneck, or by a small number of individuals’ establishing
a new population, which results in a founder effect..
Answer:Genetic drift
5) The idea of natural selection is most closely associated with _______.
Answer: Charles Darwin
Multiple Choice: Circle the best possible answer Each is worth 2 points (20 total)
6. Assume that a population is in Hardy–Weinberg equilibrium for a trait controlled by
one locus and two alleles. If the frequency of the dominant allele is 0.90, what is the
frequency of the recessive allele?
a. 0.10
b. 0.19
c. 0.81
d. None of the above
e. This cannot be answered without more information.
Answer: a
7. In a population of dovetail swallows, the frequency of the recessive a allele is 0.60.
What is the frequency of individuals homozygous dominant for the A gene?
a. 0.16
b. 0.24
c. 0.48
d. None of the above
e. This cannot be answered without more information.
Answer: c
8. There are five conditions that must be met for a population to be in Hardy–Weinberg
equilibrium. Which of the following is not one of those conditions?
a. Nonrandom mating
b. Large population size
c. No migration
d. No natural selection
e. No mutations
Answer: a
9) In the Hardy–Weinberg equation, the heterozygous individuals in a population are
represented by
a. p2.
b. 2pq.
c. q2.
d. p.
e. q.
Answer: b
10. Which of the following populations would demonstrate a population bottleneck?
a. The population of El Paso, Texas, after it has moved in its entirety to Patagonia
b. Eight male and eight female elephant seals that have survived the wreck of the Exxon
Valdez
c. A million male orangutans
d. Six male orangutans collected from a natural population in Sumatra and moved to the
San Diego Zoo
e. None of the above
Answer: b
11. _______ selection occurs when one extreme of a population contributes more
offspring to the next generation than average members of the population do.
a. Corrective
b. Directional
c. Stabilizing
d. Disruptive
e. Natural
Answer: b
12. In the Hardy–Weinberg equation, the homozygous dominant individuals in a
population are represented by
a. p2.
b. 2pq.
c. q2.
d. p.
e. q.
Answer: a
13-15. In a population of 200 individuals, 72 are homozygous recessive for the character
of eye color (cc). One hundred individuals from this population die due to a fatal disease.
Thirty-six of the survivors are homozygous recessive. Answer the following questions.
13. In the original population, the frequency of the dominant allele is
a. 0.16.
b. 0.36.
c. 0.40.
d. 0.48.
e. 0.60.
Answer: c
14. In the new population, the frequency of the dominant allele is
a. 0.16.
b. 0.36.
c. 0.40.
d. 0.48.
e. 0.60.
Answer: c
15. How many heterozygous individuals are expected in the new population?
a. 16
b. 36
c. 40
d. 48
e. 60
Answer: d
Problems: Answer in the space provide and circle your final answer(s) please. Each
is worth 4 points
16) The allele for spherical seeds in pea plants is dominant to that for wrinkled seeds. In
a population of 4000 pea plants 400 show the recessive phenotype. What is the
frequency of the homozygous dominant and heterozygous genotypes within the
population?
17) In a population of 1,000 individuals, the dominant phenotype of a trait occurs 84% of
the time. What is the frequency of the dominant and recessive alleles?
18-20 A lethal recessive condition is responsible for the death of 1 out of every 20,000
babies born in South America.
18) What is the frequency of homozygous recessive individuals in the population?
19)What is the frequency of the recessive allele in the population?
20) Assuming a population size of 300,000 people what is the number of heterozygous
individuals in the population?