Quiz: Alleles and Inherited Traits — 10 questions

1. What is an allele?

A. A version of a gene at a particular chromosome position

B. A visible trait produced by several different genes

C. A complete set of chromosomes inherited from one parent

D. A cell that carries genetic information to offspring

Answer: (A)

Explanation

An allele is a version of a gene found at a particular position on a chromosome.

2. How many alleles for a gene does an individual typically inherit, and how are they obtained?

A. Two alleles, with one inherited from each parent

B. Four alleles, with two inherited from each parent

C. Two alleles, both inherited from the mother

D. One allele, inherited from each parent in alternating generations

Answer: (A)

Explanation

An individual inherits two alleles for a gene: one allele comes from each parent.

3. An individual has two identical alleles for a particular trait. What term describes this genetic state?

A. Homozygous

B. Heterozygous

C. Dominant

D. Recessive

Answer: (A)

Explanation

An individual is homozygous when the two alleles for a trait are identical. Heterozygous refers to two different alleles.

4. An individual has two different alleles for a particular trait. What term describes this genetic state?

A. Homozygous

B. Dominant

C. Heterozygous

D. Recessive

Answer: (C)

Explanation

An individual is heterozygous when the two alleles for a trait are different. Homozygous means the alleles are identical.

5. How many copies of a dominant allele are needed for the associated trait to be visible in an individual's appearance?

A. No copies, because appearance is independent of alleles

B. Two identical copies

C. One copy

D. Two different copies

Answer: (C)

Explanation

A dominant trait is visible when an individual has just one copy of the relevant allele.

6. What happens to a recessive trait when a dominant trait is present?

A. The recessive trait becomes dominant in appearance

B. The recessive trait changes into a different allele

C. The recessive trait is visible with one allele copy

D. The recessive trait is dominated by the dominant trait

Answer: (D)

Explanation

A recessive trait is dominated by a dominant trait. In contrast, a dominant trait can be visible with one allele copy.

7. Which term describes the combination of allelic symbols representing the alleles for a trait?

A. Physical characteristic

B. Punnett square

C. Phenotype

D. Genotype

Answer: (D)

Explanation

A genotype is the allelic combination that represents the alleles for a trait. A phenotype is the trait’s physical expression.

8. A person has a particular hair color that can be observed directly. What does this observable characteristic represent?

A. The person’s inherited gene combination

B. The person’s allele pair notation

C. The person’s phenotype

D. The person’s genotype

Answer: (C)

Explanation

A phenotype is the physical expression of a trait, such as observable hair color. A genotype refers to the underlying allelic combination.

9. What does a Punnett square primarily show?

A. The physical development of offspring over time

B. The exact genetic makeup of every ancestor

C. The observable traits of one individual

D. The possible inherited gene combinations and their likelihoods

Answer: (D)

Explanation

A Punnett square displays the combinations of genes offspring could inherit and the likelihood of each combination. It does not describe one individual’s genotype directly or track development over time.

10. When constructing a Punnett square, what should be done after identifying the alleles contributed by both parents?

A. Replace the parental alleles with the offspring’s observed characteristics

B. Determine the offspring’s physical traits without considering allele combinations

C. Record only the dominant allele from each parent

D. Combine the parental alleles to identify possible offspring combinations

Answer: (D)

Explanation

The parental alleles are combined in the square to determine possible gene combinations in the offspring and the likelihood of each. Ignoring recessive alleles would produce incomplete results.