Question 1

Which of the following best describes the main difference between mitosis and meiosis in terms of chromosome number in the resulting cells?

Accepted Answer

Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically diverse haploid cells.

Question 2

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 3

Which event during meiosis is primarily responsible for generating genetic diversity among gametes?

Accepted Answer

Crossing over between homologous chromosomes during prophase I

Question 4

A human male with a mutation in a gene located on the Y chromosome will pass this mutation to:

Accepted Answer

All of his sons

Question 5

Which of the following equations correctly represents the X/A ratio for a normal human female?

Accepted Answer

$$X/A = 1.0$$

Question 6

A woman who is heterozygous for an X-linked recessive disorder and a man who is unaffected have a son. What is the probability that their son will be affected by the disorder?

Accepted Answer

$$0.5$$

Question 7

Which of the following best explains why calico cats are almost always female?

Accepted Answer

Random X-chromosome inactivation in females leads to mosaic expression of coat color genes.

Question 8

Which checkpoint in the cell cycle ensures that all chromosomes are properly attached to the spindle before proceeding to anaphase?

Accepted Answer

Metaphase checkpoint

Question 9

If nondisjunction occurs during meiosis I in a human oocyte, what is the most likely chromosomal outcome in the resulting gametes?

Accepted Answer

Half the gametes will have an extra chromosome, and half will be missing a chromosome.

Question 10

Which of the following statements about the law of independent assortment is correct?

Accepted Answer

It is explained by the random alignment of homologous chromosomes during metaphase I of meiosis.

Question 11

A male is hemizygous for an X-linked dominant trait. If he mates with a homozygous recessive female, what proportion of their daughters will express the dominant phenotype?

Accepted Answer

$$1.0$$

Question 12

Which of the following mechanisms is used by placental mammals to achieve dosage compensation?

Accepted Answer

Random inactivation of one X chromosome in each female somatic cell

Question 13

Which of the following is NOT a function of polar microtubules during mitosis?

Accepted Answer

They embed in the kinetochore and move chromosomes.

Question 14

Which of the following best describes the outcome of crossing over during prophase I of meiosis?

Accepted Answer

It increases genetic variation among gametes.

Question 15

A woman who is a carrier for hemophilia A (an X-linked recessive disorder) has children with a man who does not have hemophilia. What is the probability that their daughter will have hemophilia?

Accepted Answer

$$0.0 ($$unless the father is affected, daughters cannot be affected)

Question 16

Which of the following is a hallmark of X-linked recessive inheritance in humans?

Accepted Answer

The trait is expressed much more often in males than in females.

Question 17

Which of the following best explains the chromosome theory of inheritance?

Accepted Answer

Genes are carried on chromosomes, and chromosome behavior during meiosis explains Mendel’s laws.

Question 18

Which of the following is true regarding the separation of chromosomes during anaphase I of meiosis?

Accepted Answer

Homologous chromosomes are separated, while sister chromatids remain attached.

Question 19

Which of the following is a direct consequence of a mutation causing nondisjunction during meiosis?

Accepted Answer

Some gametes may have an abnormal number of chromosomes, leading to aneuploidy.

Question 20

Which of the following best describes the role of the synaptonemal complex during meiosis?

Accepted Answer

It facilitates the pairing and synapsis of homologous chromosomes during prophase I.

Cell Division and Chromosome Heredity: Structured Study Notes

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