Question 1

Which of the following best describes incomplete dominance?

Accepted Answer

A mix of alleles creates a new, intermediate phenotype that is distinct from either parent.

Question 2

A dihybrid cross in squash plants heterozygous for two loci affecting fruit color results in a 12:3:1 phenotypic ratio. What type of genetic interaction does this illustrate?

Accepted Answer

Dominant epistasis

Question 3

Which of the following is true about genes located on different chromosomes?

Accepted Answer

They assort independently during gamete formation.

Question 4

In a chi-square test, which formula is used to calculate the test statistic?

Accepted Answer

$$\$$chi^2$$ = \sum \frac{(O-E)^2$}{E}$$

Question 5

A cross between two Labrador Retrievers heterozygous for two loci affecting coat color produces a 9:3:4 phenotypic ratio. What is the most likely explanation?

Accepted Answer

Recessive epistasis

Question 6

Which of the following statements about lethal alleles is correct?

Accepted Answer

A lethal allele results in the death of an organism, often altering expected Mendelian ratios.

Question 7

If two genes are located on the same chromosome and are close together, which of the following is most likely?

Accepted Answer

They are likely to be inherited together due to genetic linkage.

Question 8

Which of the following best describes codominance?

Accepted Answer

Both alleles are visible in the phenotype, such as AB blood type in humans.

Question 9

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 10

In a dihybrid cross where both parents are heterozygous for two unlinked genes (AaBb x AaBb), what is the expected proportion of offspring with the genotype aabb?

Accepted Answer

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

Question 11

Which of the following is a key feature of dominant epistasis?

Accepted Answer

A dominant allele at one locus masks the expression of alleles at a second locus.

Question 12

A geneticist performs a chi-square test and obtains a $$\$$chi^2$$ value of 0.455 with 1 degree of freedom. The critical value at p=0.05$ is 3.841. What should the geneticist conclude?

Accepted Answer

Fail to reject the null hypothesis; the observed data do not significantly deviate from the expected.

Question 13

Which of the following scenarios best illustrates the concept of multiple alleles?

Accepted Answer

A gene for blood type in humans with alleles IA, IB, and i.

Question 14

If a trait skips generations in a pedigree and appears equally in males and females, what is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 15

In a test cross between a heterozygous individual (Tt) and a homozygous recessive individual (tt), what proportion of the offspring are expected to display the dominant phenotype?

Accepted Answer

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

Question 16

Which of the following is NOT a characteristic of a dominant trait in a pedigree?

Accepted Answer

Trait skips generations.

Question 17

A researcher observes a 3:1 phenotypic ratio in the F2 generation of a monohybrid cross. What does this suggest about the alleles involved?

Accepted Answer

The alleles show complete dominance.

Question 18

Which of the following best explains why the expected phenotypic ratio in a dihybrid cross may deviate from 9:3:3:1?

Accepted Answer

The genes are located on the same chromosome and are linked.

Question 19

A couple, both carriers for a recessive genetic disorder (heterozygous), want to know the probability that their child will be affected. What is the probability?

Accepted Answer

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

Question 20

Which of the following is a correct statement about the product rule in genetics?

Accepted Answer

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

Genetic Interactions, Linkage, and Patterns of Inheritance: Study Notes for Genetics

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