Question 1

Which of the following best describes the role of the centromere during mitosis?

Accepted Answer

It is responsible for the segregation of chromosomes by attaching to spindle fibers.

Question 2

During which phase of the cell cycle does DNA replication occur, and how does this affect the number of DNA molecules per chromosome?

Accepted Answer

DNA replication occurs during S phase, doubling the number of DNA molecules per chromosome.

Question 3

A human cell in metaphase of mitosis contains 46 chromosomes. How many DNA molecules are present in this cell at this stage?

Accepted Answer

$$92$$

Question 4

Which of the following events is unique to meiosis and does NOT occur during mitosis?

Accepted Answer

Pairing of homologous chromosomes and crossing over.

Question 5

What is the genetic consequence of crossing over during prophase I of meiosis?

Accepted Answer

It increases genetic variation by exchanging genetic material between nonsister chromatids of homologous chromosomes.

Question 6

If a diploid organism has $$2n = 8$$ chromosomes, how many different combinations of chromosomes are possible in its gametes due to independent assortment?

Accepted Answer

$$2^4 = 16$

Question 7

Which protein protects centromeric cohesin from degradation during anaphase I of meiosis, and what is the consequence if this protein is nonfunctional?

Accepted Answer

Shugoshin; sister chromatids may separate prematurely.

Question 8

A grasshopper cell has 24 chromosomes before meiosis. After meiosis, how many chromosomes will be present in each gamete, and what does this demonstrate about chromosome theory?

Accepted Answer

12 chromosomes; meiosis reduces chromosome number by half, supporting the chromosome theory of inheritance.

Question 9

Which of the following best explains Mendel’s Principle of Independent Assortment at the chromosomal level?

Accepted Answer

It is due to the random distribution of homologous chromosomes during anaphase I of meiosis.

Question 10

Which of the following statements about the genetic consequences of mitosis is correct?

Accepted Answer

Mitosis produces two cells that are genetically identical to each other and to the parent cell.

Question 11

A mutation prevents the breakdown of cohesin at the centromere during anaphase II of meiosis. What is the most likely outcome?

Accepted Answer

Sister chromatids fail to separate during meiosis II, leading to gametes with abnormal chromosome numbers.

Question 12

Which of the following best describes the difference between a locus and an allele?

Accepted Answer

A locus is a specific location on a chromosome, while an allele is a version of a gene found at that locus.

Question 13

During which stage of mitosis do sister chromatids separate and move toward opposite poles?

Accepted Answer

Anaphase

Question 14

If a cell with 8 chromosomes undergoes mitosis, how many chromosomes will each daughter cell have after cytokinesis?

Accepted Answer

$$8$$

Question 15

Which of the following is a direct result of the random alignment of homologous pairs during metaphase I of meiosis?

Accepted Answer

Independent assortment of alleles on different chromosomes.

Question 16

A mutation causes shugoshin to be nonfunctional during meiosis I. What is the most likely effect on chromosome segregation?

Accepted Answer

Sister chromatids will separate during anaphase I instead of anaphase II.

Question 17

Which of the following best explains why newly formed cells from meiosis are genetically different from one another and from the parental cell?

Accepted Answer

Because of crossing over and independent assortment during meiosis.

Question 18

Which of the following is true regarding the number of chromosomes and DNA molecules during the cell cycle?

Accepted Answer

The number of DNA molecules doubles after S phase, but the number of chromosomes remains the same until anaphase.

Question 19

Which of the following is a consequence of fertilization in sexually reproducing organisms?

Accepted Answer

It restores the diploid chromosome number.

Question 20

If Mendel had studied loci that were on the same chromosome, how would his observations of independent assortment have been affected?

Accepted Answer

He would have observed independent assortment only if crossing over occurred between the loci.

Chromosomes and Cellular Reproduction: Mitosis, Meiosis, and Genetic Variation

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