Question 1

During which stage of meiosis does crossing over occur, and what is its significance for genetic variation?

Accepted Answer

Crossing over occurs during Prophase I and increases genetic variation by exchanging genetic material between non-sister chromatids.

Question 2

Which of the following best describes homologous chromosomes?

Accepted Answer

They are chromosomes of the same length and centromere position, carrying the same genes but possibly different alleles.

Question 3

If a diploid cell (2n = 8) undergoes meiosis, how many chromosomes will each gamete contain?

Accepted Answer

$$n = 4$$

Question 4

What is the main difference between the alignment of chromosomes during Metaphase I of meiosis and Metaphase of mitosis?

Accepted Answer

In Metaphase I, homologous pairs align at the metaphase plate, while in mitosis, individual chromosomes align.

Question 5

Which process ensures that the diploid number of chromosomes is maintained across generations in sexually reproducing organisms?

Accepted Answer

The fusion of haploid gametes during fertilization restores the diploid number.

Question 6

A genetic disorder is caused by the failure of homologous chromosomes to separate during Anaphase I. What is this phenomenon called?

Accepted Answer

Nondisjunction

Question 7

Which of the following events does NOT contribute to genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 8

During oogenesis in humans, why is there a delay in the completion of meiosis II?

Accepted Answer

Meiosis II is completed only after fertilization by a sperm cell.

Question 9

Which of the following best explains why the four gametes produced by meiosis are genetically different from each other?

Accepted Answer

Crossing over and independent assortment create new combinations of alleles.

Question 10

A cell with a diploid number of 6 undergoes meiosis. After Telophase II and cytokinesis, how many chromosomes will each daughter cell have, and are they genetically identical?

Accepted Answer

Each will have 3 chromosomes and they are not genetically identical.

Question 11

Which of the following is a direct result of independent assortment during meiosis?

Accepted Answer

Gametes with different combinations of maternal and paternal chromosomes are produced.

Question 12

In spermatogenesis, what is the ploidy of the primary spermatocyte and the resulting spermatids?

Accepted Answer

Primary spermatocyte is diploid (2n); spermatids are haploid (n).

Question 13

Which of the following statements about meiosis II is correct?

Accepted Answer

Sister chromatids are separated, resulting in four haploid cells.

Question 14

A mutation prevents the formation of chiasmata during meiosis. What is the most likely consequence?

Accepted Answer

Reduced genetic variation due to lack of crossing over.

Question 15

Which of the following equations correctly represents the chromosome number after meiosis in a species with a diploid number of $$2n$$?

Accepted Answer

$$n$$

Question 16

Why is sexual reproduction advantageous in changing environments?

Accepted Answer

It increases genetic variation, allowing populations to adapt to new challenges.

Question 17

Which of the following best describes the difference between the products of mitosis and meiosis?

Accepted Answer

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

Question 18

A woman’s egg cell is fertilized by a sperm cell. Which equation represents the chromosome number of the resulting zygote?

Accepted Answer

$$n + n = 2n$$

Question 19

Which of the following is true regarding polar bodies in oogenesis?

Accepted Answer

They are small cells produced during oogenesis that typically do not develop into eggs.

Question 20

If a mutation caused all gametes to be diploid instead of haploid, what would be the chromosome number of the zygote after fertilization?

Accepted Answer

$$2n + 2n = 4n$$

Meiosis and Sexual Life Cycles: Mechanisms and Biological Significance

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