Question 1

A pea plant with genotype $$Yy ($$yellow seeds) is self-fertilized. According to Mendel's law of segregation, what proportion of the offspring will have green seeds if yellow is dominant to green?

Accepted Answer

$$\frac{1}{4}$$

Question 2

Which of the following best explains why a testcross is used in genetics?

Accepted Answer

To determine whether an individual with a dominant phenotype is homozygous or heterozygous

Question 3

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

Accepted Answer

A or B

Question 4

In a dihybrid cross between two individuals heterozygous for both traits ($$AaBb 	imes AaBb$$), what is the expected phenotypic ratio in the F2 generation, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 5

A geneticist observes that a single gene affects multiple traits in a mouse, including fur color, eye color, and tail length. This is an example of:

Accepted Answer

Pleiotropy

Question 6

If a woman who is a carrier for an X-linked recessive disorder (e.g., hemophilia) has children with a normal male, what is the probability that their son will have the disorder?

Accepted Answer

$$\frac{1}{2}$$

Question 7

Which of the following scenarios best illustrates incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered snapdragons produces pink-flowered offspring.

Question 8

In a pedigree, a trait appears in every generation and affected individuals have at least one affected parent. This pattern is most consistent with:

Accepted Answer

Autosomal dominant inheritance

Question 9

Which of the following best describes the law of independent assortment?

Accepted Answer

Alleles of different genes assort independently during gamete formation

Question 10

A couple has a child with cystic fibrosis, an autosomal recessive disorder. Neither parent has the disease. What is the probability that their next child will also have cystic fibrosis?

Accepted Answer

$$\frac{1}{4}$$

Question 11

Which of the following is an example of codominance?

Accepted Answer

A person with type AB blood expresses both A and B antigens equally.

Question 12

A man with genotype $$X^A Y$$ and a woman with genotype $$X^A X^a$$ have a daughter. What is the probability that the daughter is a carrier for an X-linked recessive trait?

Accepted Answer

$$\frac{1}{2}$$

Question 13

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute to a single trait, resulting in continuous variation

Question 14

If two heterozygous individuals ($$Aa) $$are crossed, what is the probability that their first two children will both be homozygous recessive?

Accepted Answer

$$\frac{1}{16}$$

Question 15

A gene for coat color in mice is epistatic to a gene for pigment deposition. If a mouse is homozygous recessive for the epistatic gene, what will be its phenotype?

Accepted Answer

It will lack pigment regardless of the pigment deposition gene

Question 16

Which of the following is NOT a feature of Mendel's experimental design that contributed to his success?

Accepted Answer

He selected traits influenced by environmental factors

Question 17

A wild-type fruit fly has red eyes, while a mutant has white eyes. If the gene for eye color is X-linked and red is dominant, what is the expected outcome of a cross between a white-eyed female and a red-eyed male?

Accepted Answer

All daughters will have red eyes; all sons will have white eyes

Question 18

Which of the following best explains why some genetic disorders are more common in males than females?

Accepted Answer

Males have only one X chromosome, so recessive X-linked alleles are always expressed

Question 19

A couple, both with genotype $$Aa$$ for a dominant disorder, are expecting a child. What is the probability that their child will be unaffected?

Accepted Answer

$$\frac{1}{4}$$

Question 20

Which of the following is an example of a multifactorial trait?

Accepted Answer

Height, which is influenced by both genetics and nutrition

Mendelian Genetics and Extensions: Principles of Inheritance

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