Question 1

In pea plants, a single gene affects both flower color and the color of the seed coat. This phenomenon, where one gene influences multiple phenotypic traits, is known as:

Accepted Answer

Pleiotropy

Question 2

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

Accepted Answer

A and B

Question 3

What is the basic difference between incomplete dominance and epistasis in terms of the number of genes involved?

Accepted Answer

Incomplete dominance involves one gene, while epistasis involves two or more genes.

Question 4

A classmate claims that the blending hypothesis is supported by the appearance of pink snapdragons from red and white parents. How would you respond using Mendelian genetics?

Accepted Answer

Pink snapdragons result from incomplete dominance, where the heterozygote shows an intermediate phenotype, but the parental traits can reappear in later generations.

Question 5

A rooster with gray feathers and a hen of the same phenotype produce offspring in the following ratio: 15 gray, 6 black, and 5 white chicks. What is the most likely genetic explanation for this result?

Accepted Answer

Epistasis involving two genes affecting feather color.

Question 6

Which of the following best describes codominance?

Accepted Answer

Both alleles in the heterozygote are fully expressed, resulting in a phenotype that shows both traits distinctly.

Question 7

In a dihybrid cross between two heterozygous pea plants for seed color (Yy) and seed shape (Rr), what is the expected phenotypic ratio in the F2 generation, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 8

Which of the following is an example of environmental influence on phenotype?

Accepted Answer

The coat color of the Arctic fox changing from brown in summer to white in winter due to temperature-sensitive pigment production.

Question 9

Human height is determined by:

Accepted Answer

Polygenic inheritance, where multiple genes contribute to the phenotype.

Question 10

If a trait is controlled by a single gene with two alleles, and the heterozygote displays a phenotype intermediate between the two homozygotes, this is an example of:

Accepted Answer

Incomplete dominance

Question 11

A family has a pattern of shirt-striping that appears to be inherited as a single-gene trait. If both parents are heterozygous for the trait, what is the expected genotypic ratio among their children?

Accepted Answer

$$1:2:1$$

Question 12

Which of the following best explains why genetic variation is important for the perpetuation of a species?

Accepted Answer

It ensures that some individuals may have traits that help them survive changing environments.

Question 13

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment production masks the expression of a gene for pigment color in mice.

Question 14

If a plant with genotype $$Rr ($$round seeds) is crossed with a plant with genotype $$rr ($$wrinkled seeds), what is the expected phenotypic ratio of the offspring?

Accepted Answer

$$1$$ round : $$1$$ wrinkled

Question 15

Which of the following best describes pleiotropy?

Accepted Answer

A single gene affects multiple, seemingly unrelated phenotypic traits.

Question 16

A cross between two heterozygous snapdragons (with pink flowers) results in what phenotypic ratio among the offspring?

Accepted Answer

$$1$$ red : $$2$$ pink : $$1$$ white

Question 17

Which of the following scenarios best illustrates polygenic inheritance?

Accepted Answer

Human skin color, which is influenced by several genes, resulting in a wide range of phenotypes.

Question 18

If a trait is influenced by both genetic and environmental factors, which of the following is the best example?

Accepted Answer

The color of hydrangea flowers changing depending on soil pH.

Question 19

In a cross involving two genes, if the observed phenotypic ratio in the offspring is $$9:7$$ instead of the expected $$9:3:3:1$$, what is the most likely explanation?

Accepted Answer

Epistasis, where one gene masks the effect of another.

Question 20

Which of the following best explains why the blending hypothesis was rejected in favor of Mendel's particulate hypothesis?

Accepted Answer

Blending inheritance could not explain the reappearance of parental traits in later generations.

Mendel and the Genetic Idea: Complex Patterns of Inheritance (Section 14.3)

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