Question 1

In a dihybrid cross between two heterozygous pea plants (RrYy x RrYy), what is the expected phenotypic ratio of the offspring?

Accepted Answer

$$9:3:3:1$$

Question 2

Which of the following best describes a dihybrid organism?

Accepted Answer

An organism that is heterozygous for two specific genes.

Question 3

If a pea plant with genotype RrYy is crossed with a pea plant with genotype rryy, what fraction of the offspring will have round and yellow seeds? (Assume R = round, r = wrinkled, Y = yellow, y = green)

Accepted Answer

$$1/2$$

Question 4

Which of the following is a consequence of independent assortment?

Accepted Answer

Heterozygous individuals can produce gametes with all possible allele combinations.

Question 5

In a dihybrid cross of AaBb x AaBb, what fraction of the offspring will be homozygous recessive for both traits?

Accepted Answer

$$1/16$$

Question 6

Which of the following statements is correct regarding monohybrid and dihybrid crosses?

Accepted Answer

A monohybrid cross involves one gene, while a dihybrid cross involves two genes.

Question 7

If black fur (B) is dominant to brown fur (b) and short tails (T) are dominant to long tails (t), what fraction of the progeny from a BbTt x BbTt cross will be expected to have black fur and long tails?

Accepted Answer

$$3/16$$

Question 8

Which of the following genotype combinations would result in a wrinkled green pea?

Accepted Answer

rryy

Question 9

What is the probability that an offspring from a cross between RrYy and rryy will be homozygous dominant for both traits?

Accepted Answer

$$0$$

Question 10

Which of the following best explains why the phenotypic ratio in a dihybrid cross is $$9:3:3:1$$?

Accepted Answer

Because the alleles for each gene assort independently during gamete formation.

Question 11

If a plant with genotype RrYy is self-crossed, what is the probability that an offspring will have the genotype RrYy?

Accepted Answer

$$1/8$$

Question 12

Which of the following crosses would produce only heterozygous offspring for both traits?

Accepted Answer

RRYY x rryy

Question 13

A plant with genotype RrYy is crossed with a plant with genotype RRYy. What is the probability that an offspring will be homozygous dominant for both traits?

Accepted Answer

$$1/8$$

Question 14

Which of the following is NOT a possible gamete produced by a plant with genotype RrYy?

Accepted Answer

RR

Question 15

If two plants with genotype RrYy are crossed, what is the probability that an offspring will be round and green?

Accepted Answer

$$3/16$$

Dihybrid Crosses and Mendelian Genetics

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