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 cross between two yellow mice results in a 2:1 ratio of yellow to gray offspring. Which genetic phenomenon explains this observation?

Accepted Answer

Lethal alleles

Question 3

Which equation correctly represents the expected phenotypic ratio for a dihybrid cross under Mendelian inheritance?

Accepted Answer

$$9:3:3:1$$

Question 4

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

Accepted Answer

Type A or Type B

Question 5

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

Accepted Answer

Co-dominance

Question 6

In a population, a dominant allele shows incomplete penetrance. What does this mean?

Accepted Answer

Not all individuals with the dominant allele express the expected phenotype.

Question 7

A genetic disorder shows variable expressivity. Which of the following is true?

Accepted Answer

Individuals with the same genotype show different degrees of phenotype severity.

Question 8

Which of the following is an example of overdominance?

Accepted Answer

Individuals heterozygous for sickle cell anemia ($$Hb^A Hb^S) $$are resistant to malaria and do not have sickle cell disease.

Question 9

Which of the following best describes recessive epistasis?

Accepted Answer

A recessive allele at one gene masks the expression of alleles at another gene.

Question 10

A woman who is a carrier for hemophilia (an X-linked recessive disorder) and a non-hemophilic man have a son. What is the probability that their son will have hemophilia?

Accepted Answer

$$0.5$$

Question 11

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

Accepted Answer

Pattern baldness in humans

Question 12

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

Accepted Answer

$$9:7$$

Question 13

A man with blood type A and a woman with blood type B have a child with blood type O. What are the genotypes of the parents?

Accepted Answer

Both are heterozygotes: $$I^A i$$ and $$I^B i$$

Question 14

Which of the following scenarios best illustrates the concept of gene redundancy?

Accepted Answer

A plant with a mutation in one gene still produces the normal phenotype because another gene compensates for the loss.

Question 15

Which of the following is true about the inheritance of X-linked recessive traits?

Accepted Answer

Males are more likely to express the trait because they have only one X chromosome.

Question 16

Which of the following best explains why a woman who is heterozygous for an X-linked mutation may show irregular patches of affected tissue?

Accepted Answer

Random X-chromosome inactivation in different cells

Question 17

A geneticist observes that a certain trait is only expressed in males, regardless of genotype. What is the most likely mode of inheritance?

Accepted Answer

Y-linked inheritance

Question 18

Which of the following is a consequence of a mismatched blood transfusion?

Accepted Answer

The recipient's immune system attacks the donor red blood cells, causing agglutination.

Question 19

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

Accepted Answer

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

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

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