CLEP Biology Genetics & Biological Diversity 4 — Questions and Answers
Question 1: A woman who is a carrier for hemophilia (X^H X^h) has children with an unaffected man (X^H Y). What is the probability that a son will be affected?
- 0%
- 25%
- 50% (Correct answer)
- 100%
Correct answer: 50%
Sons receive their X chromosome only from their mother; since mom is a carrier, each son has a 50% chance of inheriting the hemophilia allele.
Question 2: Which kingdom is characterized by organisms that are eukaryotic, heterotrophic, and absorb nutrients through their cell walls?
- Plantae
- Protista
- Fungi (Correct answer)
- Animalia
Correct answer: Fungi
Fungi are eukaryotic, heterotrophic organisms that digest food externally and absorb the nutrients through their cell walls.
Question 3: What is the result of nondisjunction during meiosis II in a cell with 2n = 4?
- Gametes with n+1 and n-1 chromosomes
- All gametes with the normal number of chromosomes
- One gamete with an extra chromosome and one missing a chromosome, while two are normal (Correct answer)
- All gametes with double the normal number
Correct answer: One gamete with an extra chromosome and one missing a chromosome, while two are normal
Nondisjunction in meiosis II affects only one pair of sister chromatids, producing two abnormal gametes (n+1 and n-1) and two normal ones.
Question 4: Which of the following correctly distinguishes Archaea from Bacteria?
- Archaea have membrane-bound nuclei
- Archaea lack peptidoglycan in their cell walls (Correct answer)
- Archaea cannot survive in extreme environments
- Archaea use the same RNA polymerase as Bacteria
Correct answer: Archaea lack peptidoglycan in their cell walls
Archaea lack peptidoglycan in their cell walls (they use pseudopeptidoglycan or other polymers), which is a key biochemical distinction from Bacteria.
Question 5: In a test cross, a dominant phenotype individual is crossed with a homozygous recessive individual. A 1:1 offspring ratio indicates the dominant parent was:
- Homozygous dominant
- Heterozygous (Correct answer)
- Codominant
- Hemizygous
Correct answer: Heterozygous
A 1:1 ratio in a test cross results when the dominant-phenotype parent is heterozygous (Aa), producing Aa and aa offspring in equal proportions.
Question 6: The concept of adaptive radiation best explains which of the following observations?
- Convergent evolution of wings in bats and birds
- Divergence of Darwin's finches into many species with different beak shapes (Correct answer)
- Stabilizing selection maintaining beak size in a population
- The extinction of the dodo bird
Correct answer: Divergence of Darwin's finches into many species with different beak shapes
Adaptive radiation occurs when a single ancestral species rapidly diversifies into multiple species that exploit different ecological niches, as seen in Darwin's finches.
Question 7: What does it mean when two genes are said to be 'linked'?
- They code for proteins that interact physically
- They are located on the same chromosome (Correct answer)
- They always assort independently
- They are expressed at the same time
Correct answer: They are located on the same chromosome
Linked genes are located on the same chromosome and tend to be inherited together, violating Mendel's law of independent assortment.
CLEP Biology Genetics & Biological Diversity 4
A woman who is a carrier for hemophilia (X^H X^h) has children with an unaffected man (X^H Y).
What is the probability that a son will be affected?