Q: A cross between a red-flowered snapdragon (R1R1) and a white-flowered snapdragon (R2R2) produces all pink-flowered offspring (R1R2). If two pink-flowered snapdragons are crossed, what is the expected phenotypic ratio in the F2 generation?

$$1 \text{ red} : 2 \text{ pink} : 1 \text{ white}$$

Q: In a cross between two yellow mice (genotype $$A^Y A$$), what is the expected genotypic ratio among the viable offspring?

$$2 \text{ yellow} : 1 \text{ agouti}$$

Question 1

Which of the following best describes incomplete dominance?

Accepted Answer

A situation where the heterozygote displays a phenotype intermediate between the two homozygotes.

Question 2

A cross between a red-flowered snapdragon (R1R1) and a white-flowered snapdragon (R2R2) produces all pink-flowered offspring (R1R2). If two pink-flowered snapdragons are crossed, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$1 	ext{ red} : 2 	ext{ pink} : 1 	ext{ white}$$

Question 3

Which of the following is an example of codominance?

Accepted Answer

ABO blood type in humans, where IA and IB alleles are both expressed in the AB phenotype.

Question 4

A couple with genotypes IAIO and IBIO for the ABO blood group have children. What is the probability that their child will be a universal donor?

Accepted Answer

$$0.25$$

Question 5

Which of the following best explains why the Bombay phenotype can result in an individual with genotype IAIB appearing as blood type O?

Accepted Answer

A mutation in the H locus prevents the formation of the H antigen, so A and B antigens cannot be expressed.

Question 6

In a cross between two yellow mice (genotype $$A^Y A$$), what is the expected genotypic ratio among the viable offspring?

Accepted Answer

$$2 	ext{ yellow} : 1 	ext{ agouti}$$

Question 7

A woman with normal color vision and a man with normal color vision have a son who is color blind. Which of the following is the most likely genotype of the mother?

Accepted Answer

Heterozygous (Cc)

Question 8

Which of the following statements about pleiotropy is correct?

Accepted Answer

Pleiotropy occurs when a single gene affects multiple traits.

Question 9

Which of the following best describes penetrance?

Accepted Answer

The percentage of individuals with a given genotype who express the expected phenotype.

Question 10

A cross between two true-breeding white pea plants (AAbb × aaBB) produces all purple F1 offspring. When these F1 plants are self-crossed, the F2 generation shows a 9:7 ratio of purple to white plants. What genetic phenomenon explains this result?

Accepted Answer

Epistasis (complementary gene interaction)

Question 11

Which of the following is true about mitochondrial inheritance in humans?

Accepted Answer

Mitochondrial genes are inherited only from the mother.

Question 12

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

Accepted Answer

A and B only

Question 13

Which of the following best describes the concept of genetic anticipation?

Accepted Answer

A trait that appears earlier and more severely in successive generations.

Question 14

In a dihybrid cross involving two genes with simple dominance, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 15

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

Accepted Answer

Pattern baldness in humans

Question 16

A striped corn mutant from Mexico is crossed with a striped mutant from Peru, and all offspring are green. What does this result indicate?

Accepted Answer

The mutations are in different genes (complementation).

Question 17

Which of the following best describes the molecular basis of the O blood type in the ABO system?

Accepted Answer

The O allele encodes a non-functional glycosyltransferase enzyme.

Question 18

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

Accepted Answer

Males are hemizygous for X-linked genes.

Question 19

A temperature-sensitive mutation in a Himalayan rabbit causes dark fur only on the cooler parts of the body. What genetic concept does this illustrate?

Accepted Answer

Conditional mutation

Question 20

Which of the following is an example of extranuclear inheritance?

Accepted Answer

Inheritance of mitochondrial diseases

Modification of Mendelian Ratios: Non-Mendelian Inheritance Patterns

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