Question 1

Which of the following best describes Mendel’s principle of segregation?

Accepted Answer

Alleles of a gene separate into different gametes during meiosis I.

Question 2

A pea plant with genotype $$YyRr is $$self-fertilized. What is the probability that an offspring will have yellow, wrinkled seeds? (Yellow is dominant to green, round is dominant to wrinkled.)

Accepted Answer

$$\frac{3}{16}$$

Question 3

Which experimental result would support the blending inheritance hypothesis rather than Mendel’s particulate inheritance hypothesis?

Accepted Answer

F1 offspring of a cross between round and wrinkled peas all have slightly wrinkled seeds.

Question 4

In a testcross, a pea plant with purple flowers (dominant) is crossed with a white-flowered plant (recessive). If half the offspring are purple and half are white, what is the genotype of the purple-flowered parent?

Accepted Answer

Heterozygous

Question 5

Which of the following is an example of a polymorphic trait as studied by Mendel?

Accepted Answer

Seed color in peas, which can be yellow or green

Question 6

A woman who is a carrier for an X-linked recessive disorder and a man who is unaffected have a son. What is the probability that their son will be affected?

Accepted Answer

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

Question 7

Which of the following best explains why genes located close together on the same chromosome tend to be inherited together?

Accepted Answer

They are less likely to be separated by crossing over during meiosis.

Question 8

If two heterozygous individuals ($$Aa) $$are crossed, what is the probability that their offspring will be homozygous dominant or heterozygous?

Accepted Answer

$$\frac{3}{4}$$

Question 9

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene mutation causing both lung and digestive problems in cystic fibrosis

Question 10

A dihybrid cross between two $$AaBb$$ individuals produces which phenotypic ratio in the F2 generation, assuming independent assortment?

Accepted Answer

9:3:3:1

Question 11

Which of the following statements about incomplete dominance is correct?

Accepted Answer

The heterozygote expresses a phenotype intermediate between the two homozygotes.

Question 12

In a population, a gene has three alleles: $$I^A$$, $$I^B$$, and $$i. $$Which human trait is determined by these alleles?

Accepted Answer

ABO blood type

Question 13

Which of the following best describes the chromosomal theory of inheritance?

Accepted Answer

Genes are located on chromosomes and their behavior during meiosis explains inheritance patterns.

Question 14

A Labrador retriever’s coat color is determined by two genes: one for pigment color (B = black, b = brown) and one for pigment deposition (E = deposition, e = no deposition). What is the expected coat color of the offspring from a cross between a homozygous black ($$BBEE) $$and a homozygous yellow ($$bbee) $$Labrador?

Accepted Answer

All black with genotype $$BbEe$$

Question 15

Which of the following is a quantitative trait?

Accepted Answer

Human height, which shows continuous variation

Question 16

A pedigree shows a trait that appears equally in males and females and skips generations. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 17

Which of the following best explains why males are more likely to express X-linked recessive traits?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 18

Which of the following is an example of gene interaction (epistasis)?

Accepted Answer

One gene modifies the expression of another gene, such as coat color in Labrador retrievers.

Question 19

If a trait is determined by both genetic and environmental factors, which of the following is true?

Accepted Answer

Phenotype is influenced by both genotype and environment.

Question 20

Which of the following best describes a testcross?

Accepted Answer

A cross between an individual with a dominant phenotype and a homozygous recessive individual to determine genotype.

Mendel and the Gene: Principles of Inheritance

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