Question 1

Which of the following best describes Mendel’s Second Law (Law of Independent Assortment)?

Accepted Answer

Alleles of different genes assort independently of one another during gamete formation if they are on different chromosomes.

Question 2

In a dihybrid cross between two heterozygous pea plants (YyRr x YyRr), what is the probability of obtaining an offspring with yellow, wrinkled seeds? (Yellow is dominant to green, round is dominant to wrinkled.)

Accepted Answer

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

Question 3

If a plant with genotype A/A B/b C/c d/d is self-crossed, how many different genotypes can be produced among the offspring?

Accepted Answer

6

Question 4

Which of the following is a direct consequence of independent assortment during meiosis?

Accepted Answer

Each gamete receives a random combination of maternal and paternal chromosomes.

Question 5

A cross between two pea plants produces the following F2 phenotypic ratio: 9:3:3:1. What does this ratio indicate about the genes involved?

Accepted Answer

The genes are on different chromosomes and assort independently.

Question 6

In a cross between two individuals heterozygous for three genes (RrYyPp x RrYyPp), what is the probability of producing an offspring that is homozygous recessive for all three genes?

Accepted Answer

$$\frac{1}{64}$$

Question 7

Which of the following best explains why mitochondrial genes are usually inherited maternally?

Accepted Answer

Egg cells contribute most of the cytoplasm (and organelles) to the zygote.

Question 8

If you cross a pale Chagrian male heterozygous for long horns (Ll) with a blue, heterozygous female with short horns (ll), what is the expected phenotypic ratio for horn length in their offspring?

Accepted Answer

1 long : 1 short

Question 9

A plant has two pigment genes, A and B. Each dominant allele produces 10 units of pigment, and each recessive allele produces 1 unit. What is the total pigment in a plant with genotype AaBb?

Accepted Answer

22 units

Question 10

In a population, a continuous trait such as height is observed to follow a bell-shaped curve. What is the most likely genetic explanation for this pattern?

Accepted Answer

The trait is influenced by multiple genes with additive effects (polygenic inheritance).

Question 11

If a diploid organism has 4 pairs of chromosomes, how many different combinations of chromosomes can be produced in its gametes due to independent assortment?

Accepted Answer

$$2^4 = 16$

Question 12

Which of the following is NOT a requirement for Mendel’s Second Law to apply to two genes?

Accepted Answer

The genes must be closely linked on the same chromosome.

Question 13

In a cross AaBb x AaBb, what is the probability of producing an offspring with genotype AABB?

Accepted Answer

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

Question 14

Which of the following best describes the product rule in probability as applied to genetics?

Accepted Answer

The probability of two independent events occurring together is the product of their individual probabilities.

Question 15

If you self-cross a plant with genotype A/A B/b C/c d/d, how many different phenotypes can be produced among the offspring?

Accepted Answer

4

Question 16

Which stage of meiosis is most critical for the independent assortment of chromosomes?

Accepted Answer

Metaphase I

Question 17

In a polygenic inheritance system where each dominant allele adds 10 cm to height and each recessive allele adds 2 cm, what is the expected height of an individual with genotype H1/h1 H2/h2 h3/h3?

Accepted Answer

26 cm

Question 18

Which of the following scenarios would most likely result in a 1:1:1:1 phenotypic ratio in the offspring?

Accepted Answer

A test cross between a dihybrid and a homozygous recessive individual.

Question 19

Which of the following statements about Punnett squares is TRUE when analyzing more than two genes?

Accepted Answer

Punnett squares become increasingly complex and impractical as the number of genes increases.

Question 20

Which of the following best describes heteroplasmy?

Accepted Answer

The presence of multiple types of mitochondrial DNA within a single cell.

Mendel’s Second Law: Independent Assortment and Probability in Genetics

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