Question 1

Which of the following best describes incomplete dominance in a genetic cross?

Accepted Answer

The heterozygote expresses a phenotype that is intermediate between the two homozygotes.

Question 2

A woman with type AB blood and a man with type O blood have a child. What are the possible blood types of their child?

Accepted Answer

Type A or Type B

Question 3

Which equation correctly represents the expected phenotypic ratio from a monohybrid cross with complete dominance?

Accepted Answer

$$3:1$$

Question 4

In a population, a dominant allele codes for a functional enzyme, while a recessive allele codes for a non-functional enzyme. If the substrate is limiting, what is the likely outcome for the heterozygote?

Accepted Answer

The heterozygote will have a phenotype similar to the dominant homozygote.

Question 5

A cross between two yellow mice (heterozygous for a lethal allele) produces offspring in a 2:1 ratio of yellow to gray. What is the most likely explanation?

Accepted Answer

The yellow allele is lethal in the homozygous state.

Question 6

Which of the following best explains why individuals with the genotype $$I^A I^B$$ for the ABO blood group express both A and B antigens on their red blood cells?

Accepted Answer

Co-dominance

Question 7

A woman who is heterozygous for an X-linked recessive disorder has irregular patches of skin lacking sweat glands. What is the genetic explanation for this pattern?

Accepted Answer

Random X-chromosome inactivation in different cells

Question 8

Which of the following is an example of overdominance?

Accepted Answer

Heterozygotes for sickle cell anemia are resistant to malaria and do not have sickle cell disease.

Question 9

Which of the following best describes epistasis?

Accepted Answer

One gene masks the expression of another gene at a different locus.

Question 10

A man with normal clotting and a woman who is a carrier for hemophilia (X-linked recessive) have a son who has hemophilia. What is the genotype of the mother?

Accepted Answer

$$X^h X^+$$

Question 11

Which of the following is true about penetrance?

Accepted Answer

Penetrance refers to the proportion of individuals with a particular genotype that actually express the expected phenotype.

Question 12

In a case of duplicate recessive epistasis, what phenotypic ratio is expected in the F2 generation from a dihybrid cross?

Accepted Answer

$$9:7$$

Question 13

Which of the following is a real-world example of a sex-influenced trait?

Accepted Answer

Pattern baldness in humans

Question 14

A geneticist observes that a certain trait appears only in males and is passed from father to all sons. What is the most likely mode of inheritance?

Accepted Answer

Y-linked

Question 15

Which of the following best explains why the sickle cell allele is found at high frequency in regions where malaria is prevalent?

Accepted Answer

Heterozygotes have increased resistance to malaria.

Question 16

Which of the following is an example of a gene with multiple alleles and an allelic series?

Accepted Answer

The flower color gene with alleles $$C^+$$, $$C^{50}$$, $$C^{20}$$, and $$C^0$$

Question 17

Which of the following best describes the difference between dominance and epistasis?

Accepted Answer

Dominance involves alleles of the same gene, while epistasis involves interactions between different genes.

Question 18

A woman with genotype $$X^h X^+ ($$carrier for hemophilia) and a man with genotype $$X^+ Y$$ have a daughter. What is the probability that the daughter is a carrier for hemophilia?

Accepted Answer

$$0.5$$

Question 19

Which of the following is a likely outcome of a mismatched blood transfusion (e.g., type A blood given to a type B recipient)?

Accepted Answer

The recipient's immune system will attack the donor red blood cells.

Extensions and Modifications of Mendel’s Laws: Advanced Patterns of Inheritance

Study Guide - Practice Questions

Study Guide - Flashcards