Question 1

Which of the following best explains how sexual reproduction increases genetic variability in offspring?

Accepted Answer

It allows for the combination of alleles from two parents, resulting in new allele combinations.

Question 2

During meiosis, what is the significance of crossing over between homologous chromosomes?

Accepted Answer

It results in the exchange of genetic material, increasing genetic diversity among gametes.

Question 3

If a human cell with 46 chromosomes undergoes meiosis, how many chromosomes will each resulting gamete contain?

Accepted Answer

$$23$$

Question 4

Which event during meiosis is most directly responsible for the independent assortment of genes?

Accepted Answer

Random alignment of homologous chromosome pairs at the metaphase I plate

Question 5

A genetic disorder is caused by nondisjunction during meiosis, resulting in a zygote with three copies of chromosome 21. What is this condition called?

Accepted Answer

Down syndrome

Question 6

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

Accepted Answer

Mitosis produces cells with the same chromosome number as the parent; meiosis produces cells with half the chromosome number.

Question 7

Which of the following is a direct result of nondisjunction during meiosis?

Accepted Answer

Some gametes have an abnormal number of chromosomes.

Question 8

In humans, what is the chromosomal composition of a male with Klinefelter syndrome?

Accepted Answer

$$44 + XXY$$

Question 9

Which process ensures that offspring inherit a unique combination of alleles from both parents?

Accepted Answer

Random fertilization

Question 10

A woman is a carrier for a genetic disorder caused by nondisjunction of the sex chromosomes. Which of the following karyotypes could result from this error?

Accepted Answer

$$44 + XO$$

Question 11

Which of the following best explains why siblings from the same parents can look very different from each other?

Accepted Answer

Independent assortment and crossing over during meiosis create new combinations of alleles.

Question 12

During which phase of meiosis do homologous chromosomes separate and move toward opposite poles?

Accepted Answer

Anaphase I

Question 13

If a diploid organism has a haploid number $$n = 8$$, how many chromosomes are present in its somatic cells?

Accepted Answer

$$16$$

Question 14

Which of the following is NOT a source of genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 15

A plant species has a diploid number of $$2n = 14. $$After meiosis, how many chromosomes will each gamete contain?

Accepted Answer

$$7$$

Question 16

Which of the following best describes the outcome if nondisjunction occurs during meiosis II in oogenesis?

Accepted Answer

Half of the eggs will have a normal chromosome number, and half will be abnormal.

Question 17

Which of the following is a consequence of Turner syndrome ($$44 + XO) in $$humans?

Accepted Answer

Individuals are phenotypically female but lack secondary sexual development.

Question 18

Which of the following statements about meiosis is correct?

Accepted Answer

Meiosis reduces the chromosome number by half, producing haploid cells.

Question 19

If a sperm cell contains $$24$$ chromosomes instead of $$23$$, which of the following is the most likely explanation?

Accepted Answer

Nondisjunction occurred during meiosis in the father.

Question 20

Which of the following best explains why Down syndrome is more common than other autosomal trisomies?

Accepted Answer

Chromosome 21 is smaller and contains fewer genes, so trisomy is more compatible with life.

Meiosis, Sexual Reproduction, and Genetic Variation: Study Notes

Study Guide - Practice Questions

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