Question 1

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype refers to the alleles present in an individual, while phenotype refers to the outward appearance.

Question 2

In Mendel’s monohybrid cross of Rr x Rr (where R = round, r = wrinkled), what is the probability of obtaining a wrinkled seed?

Accepted Answer

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

Question 3

A plant with genotype Rr is crossed with a plant with genotype rr. What is the expected ratio of round to wrinkled seeds in the offspring?

Accepted Answer

1 round : 1 wrinkled

Question 4

Which statement correctly explains why the r allele is recessive at the molecular level?

Accepted Answer

The r allele codes for a non-functional enzyme due to a mutation that creates an early stop codon.

Question 5

If a pea plant with round seeds (unknown genotype) is testcrossed with a wrinkled seed plant, and half the offspring have wrinkled seeds, what is the genotype of the round-seeded parent?

Accepted Answer

Rr

Question 6

Which of the following is an example of a heterozygote?

Accepted Answer

Rr

Question 7

In a dihybrid cross RrYy x RrYy, what is the probability of obtaining an offspring with genotype rryy?

Accepted Answer

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

Question 8

Which rule would you use to calculate the probability of an offspring being either RR or Rr in a monohybrid cross?

Accepted Answer

Sum Rule

Question 9

A plant with genotype RrYy produces which of the following gametes according to the FOIL method?

Accepted Answer

RY, Ry, rY, ry

Question 10

If two heterozygous plants (Rr) are crossed, what is the expected genotypic ratio among the offspring?

Accepted Answer

1 RR : 2 Rr : 1 rr

Question 11

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

Accepted Answer

Alleles for different genes assort independently because they are located on different chromosomes.

Question 12

A plant with genotype RRyy is crossed with a plant with genotype rryy. What is the genotype of all F1 offspring?

Accepted Answer

Rryy

Question 13

If the probability of a plant having round seeds is $$\frac{3}{4}$$ and yellow seeds is $$\frac{3}{4}$$, what is the probability of a plant having both round and yellow seeds in a dihybrid cross?

Accepted Answer

$$\frac{9}{16}$$

Question 14

Which of the following crosses would you use to determine if a dominant phenotype is homozygous or heterozygous?

Accepted Answer

Testcross

Question 15

In a dihybrid cross, what is the expected phenotypic ratio for the F2 generation if both genes assort independently and show complete dominance?

Accepted Answer

9:3:3:1

Question 16

A mutation in the r allele creates an early stop codon. What is the most likely consequence for the enzyme produced?

Accepted Answer

The enzyme is non-functional and cannot synthesize amylopectin.

Question 17

Which probability rule would you use to determine the chance of rolling a 2 or a 5 on a single die?

Accepted Answer

Sum Rule

Question 18

If a plant is homozygous dominant for seed shape, what is its genotype?

Accepted Answer

RR

Question 19

Which of the following best explains why a heterozygote (Rr) for seed shape has round seeds?

Accepted Answer

The R allele produces enough functional enzyme to mask the effect of the r allele.

Question 20

In a cross between two heterozygous yellow, round-seeded pea plants (RrYy x RrYy), what is the probability of obtaining an offspring with genotype RrYy?

Accepted Answer

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

Genetics: Mendelian Inheritance, Probability, and Genetic Crosses

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