Question 1

Which of the following best explains why a dihybrid cross between two heterozygotes (GgWw × GgWw) produces a 9:3:3:1 phenotypic ratio in the F₂ generation?

Accepted Answer

Because the alleles of each gene segregate independently due to the random alignment of homologous chromosomes during meiosis.

Question 2

A plant with genotype Aa is crossed with another Aa plant. What is the probability that an offspring will be homozygous recessive (aa)?

Accepted Answer

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

Question 3

Which process during meiosis is primarily responsible for generating recombinant gametes in a dihybrid individual?

Accepted Answer

Crossing over between homologous chromosomes

Question 4

In a genetic scenario where two genes (B/b and Y/y) both influence body color but do not interact, what is the expected phenotypic outcome if both genes are heterozygous (BbYy)?

Accepted Answer

Four phenotypes will be observed, each corresponding to a different combination of alleles.

Question 5

Which of the following is an example of recessive epistasis?

Accepted Answer

A gene that masks the effect of another gene only when it is homozygous recessive.

Question 6

If a gene for pigment synthesis (C/c) and a gene for pigment transport (W/w) both affect eye color, what phenotype would result from the genotype ccWw?

Accepted Answer

No pigment in the eyes

Question 7

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

Accepted Answer

Alleles of genes on different chromosomes assort independently during meiosis.

Question 8

A dihybrid individual (GgWw) produces four types of gametes: GW, Gw, gW, and gw. What is the probability of producing a gamete with genotype Gw?

Accepted Answer

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

Question 9

Which of the following is NOT a source of genetic variation during inheritance?

Accepted Answer

Replication of chromosomes during mitosis

Question 10

In a cross between two pure-breeding pea plants, one with genotype GGWW (yellow, round) and one with ggww (green, wrinkled), what will be the genotype of all F₁ offspring?

Accepted Answer

GgWw

Question 11

If a mutation prevents the synthesis of pigment in the eye (cc genotype), what will be the phenotype regardless of the W gene alleles?

Accepted Answer

No pigment in the eyes

Question 12

Which of the following scenarios best illustrates gene interaction (epistasis)?

Accepted Answer

One gene masks or modifies the expression of another gene affecting the same trait.

Question 13

A wild type parakeet has genotype BBYY. If both genes contribute independently to body color, what would be the expected phenotype of a bbYy parakeet?

Accepted Answer

A different color due to the presence of the bb genotype

Question 14

Which of the following best explains why the inheritance of gene G does not affect the inheritance of gene W in a dihybrid cross?

Accepted Answer

Genes G and W are located on different chromosomes and assort independently.

Question 15

If a plant with genotype AaBb is self-crossed, what is the probability of obtaining an offspring with genotype aabb?

Accepted Answer

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

Question 16

Which of the following is a direct result of crossing over during meiosis?

Accepted Answer

Physical exchange of DNA between homologous chromosomes

Question 17

A geneticist observes that two genes on different chromosomes do not influence each other's inheritance. Which law does this observation support?

Accepted Answer

Law of Independent Assortment

Question 18

In a scenario where a precursor cannot be converted to pigment due to a mutation in the C gene (cc), but the W gene is functional, what is the expected eye color phenotype?

Accepted Answer

No pigment in the eyes

Question 19

Which of the following best describes the outcome of independent assortment during meiosis?

Accepted Answer

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

Sources of Genetic Variation and Patterns of Inheritance

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