Question 1

Which of the following best explains why siblings from the same parents are similar but not identical genetically?

Accepted Answer

Genetic variation is introduced by crossing over, independent assortment, and random fertilization during meiosis.

Question 2

During which phase of meiosis does crossing over occur, and what is its significance?

Accepted Answer

Prophase I; it increases genetic diversity by exchanging DNA between homologous chromosomes.

Question 3

A human somatic cell contains 46 chromosomes. After meiosis, how many chromosomes will each gamete contain?

Accepted Answer

23

Question 4

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

Accepted Answer

M checkpoint (spindle checkpoint)

Question 5

What is the function of a tumor suppressor gene such as p53, and what happens if it is mutated?

Accepted Answer

It halts the cell cycle if DNA is damaged; mutation can lead to uncontrolled cell division and cancer.

Question 6

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They are two chromosomes, one from each parent, coding for the same traits.

Question 7

What is the role of cyclins and CDKs in the cell cycle?

Accepted Answer

Cyclins activate CDKs, which regulate progression through cell cycle checkpoints.

Question 8

Which event distinguishes meiosis I from mitosis?

Accepted Answer

Formation of tetrads and crossing over

Question 9

If a cell undergoes meiosis but fails to separate homologous chromosomes during anaphase I, what is the likely outcome?

Accepted Answer

Some gametes will have extra chromosomes, and some will have fewer, leading to aneuploidy.

Question 10

Which formula correctly represents the reduction in chromosome number during meiosis?

Accepted Answer

$$2n \rightarrow n$$

Question 11

Which process is responsible for the random alignment of homologous chromosomes during metaphase I, increasing genetic diversity?

Accepted Answer

Independent assortment

Question 12

A cell with 2n = 6 undergoes meiosis. After meiosis II, how many chromosomes will each daughter cell have?

Accepted Answer

3

Question 13

Which of the following is NOT a mechanism that increases genetic variation in sexually reproducing organisms?

Accepted Answer

Binary fission

Question 14

What is the main difference between the products of mitosis and meiosis?

Accepted Answer

Mitosis produces two diploid cells identical to the parent; meiosis produces four haploid cells genetically different from each other and the parent.

Question 15

During which stage of meiosis are homologous chromosomes separated?

Accepted Answer

Anaphase I

Question 16

Which of the following best describes the formation of a tetrad?

Accepted Answer

Two homologous chromosomes, each with sister chromatids, pair up during prophase I.

Question 17

If fertilization occurred between two gametes each with 23 chromosomes, what would be the chromosome number of the resulting zygote?

Accepted Answer

46

Question 18

Which of the following is true about sister chromatids?

Accepted Answer

They are formed by the replication of a single chromosome and are genetically identical.

Question 19

Which of the following best describes the outcome of meiosis II?

Accepted Answer

Sister chromatids are separated, resulting in haploid cells.

Question 20

Which equation represents the restoration of chromosome number after fertilization?

Accepted Answer

$$n + n = 2n$$

Meiosis: Mechanisms and Significance in Sexual Reproduction

Study Guide - Practice Questions