Question 1

Which of the following best describes Mendel’s conclusion about how traits are passed from one generation to the next?

Accepted Answer

Traits are inherited as discrete units, which we now call genes.

Question 2

Which equation correctly represents the relationship between genotype and phenotype frequencies in a population under Hardy-Weinberg equilibrium?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 3

A cell with 2n = 6 undergoes meiosis. How many chromosomes will each gamete contain?

Accepted Answer

3

Question 4

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis results in genetically identical cells, while meiosis increases genetic diversity.

Question 5

A heterozygous individual for a gene with incomplete dominance is crossed with a homozygous recessive individual. What phenotypic ratio is expected in the offspring?

Accepted Answer

1:1

Question 6

Which of the following best explains why X-linked recessive traits are more common in males than females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will result in the trait.

Question 7

If a child is born with Down syndrome due to nondisjunction, at which stage did the error most likely occur?

Accepted Answer

Anaphase I or II of meiosis

Question 8

Which of the following is an example of codominance?

Accepted Answer

A person with AB blood type expressing both A and B antigens.

Question 9

A woman who is heteroplasmic for a mitochondrial mutation has children with a man who is wild-type. What is the expected outcome for their children?

Accepted Answer

All children may inherit the mutation, but the proportion of mutant mitochondria can vary.

Question 10

Which of the following best describes the effect of a pericentric inversion on recombination?

Accepted Answer

It can suppress recombination within the inverted region, leading to abnormal gametes.

Question 11

Which of the following is a real-world example of a lethal allele?

Accepted Answer

The homozygous dominant genotype for the yellow coat color in mice ($$YY) is $$lethal.

Question 12

Which of the following best explains the concept of independent assortment?

Accepted Answer

Alleles of different genes segregate independently during gamete formation.

Question 13

A pedigree shows a trait that appears only in males and is passed from father to all sons. What is the most likely mode of inheritance?

Accepted Answer

Y-linked inheritance

Question 14

Which of the following is a consequence of X-inactivation in mammals?

Accepted Answer

Females are mosaics for X-linked gene expression.

Question 15

Which of the following best describes the outcome of a cross between two heterozygotes for a gene showing incomplete dominance?

Accepted Answer

1:2:1 phenotypic ratio

Question 16

Which of the following is a likely result of a Robertsonian translocation?

Accepted Answer

Fusion of two acrocentric chromosomes to form a single chromosome.

Question 17

A geneticist observes that a certain trait is inherited only from the mother, regardless of the father's genotype. What is the most likely explanation?

Accepted Answer

Mitochondrial inheritance

Question 18

Which of the following best describes the effect of a null allele?

Accepted Answer

It results in complete loss of function of the gene product.

Question 19

Which of the following is a real-world example of incomplete dominance?

Accepted Answer

A cross between red and white snapdragons produces pink offspring.

Question 20

Which of the following best explains why crossing over during meiosis is important for genetic diversity?

Accepted Answer

It creates new combinations of alleles on chromosomes.

Genetics Study Guide: Core Concepts and Objectives

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