Question 1

Which of the following best describes the outcome of meiosis in terms of chromosome number and genetic composition?

Accepted Answer

Four daughter cells, each with half the chromosome number of the parent cell and genetically unique.

Question 2

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

Accepted Answer

Prophase I; it increases genetic variation by exchanging DNA between non-sister chromatids.

Question 3

If a diploid organism has a haploid number $$n = 8$$, how many chromosomes will be present in a gamete after meiosis?

Accepted Answer

$$8$$

Question 4

Which process is responsible for restoring the diploid chromosome number in sexually reproducing organisms?

Accepted Answer

Fertilization

Question 5

What is the main difference between homologous chromosomes and sister chromatids?

Accepted Answer

Homologous chromosomes carry the same genes but may have different alleles, while sister chromatids are identical copies formed after DNA replication.

Question 6

Which event during meiosis I is a key source of genetic variation?

Accepted Answer

Independent assortment of homologous pairs

Question 7

A human cell with 47 chromosomes is most likely the result of which meiotic error?

Accepted Answer

Nondisjunction leading to trisomy

Question 8

Which formula correctly represents the restoration of the diploid number during fertilization?

Accepted Answer

$$n + n = 2n$$

Question 9

Which of the following best explains why sexual reproduction is advantageous in changing environments?

Accepted Answer

It allows for genetic recombination and variation, increasing the likelihood of survival under new conditions.

Question 10

In a species where $$2n = 6$$, how many possible combinations of chromosomes can result from independent assortment during meiosis?

Accepted Answer

$$2^3 = 8$

Question 11

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

Accepted Answer

Replication of DNA during S phase

Question 12

What is the result of first-division nondisjunction during meiosis?

Accepted Answer

Half the gametes have $$n+1$$ chromosomes and half have $$n-1$$ chromosomes.

Question 13

Which term describes the position of a gene on a chromosome?

Accepted Answer

Locus

Question 14

Which of the following statements about polyploidy is correct?

Accepted Answer

Polyploidy refers to having more than two sets of chromosomes.

Question 15

Which hypothesis explains the evolutionary benefit of meiosis by removing deleterious mutations from a population?

Accepted Answer

Purifying selection hypothesis

Question 16

What is the ploidy of a zygote formed by the fusion of two gametes?

Accepted Answer

Diploid ($$2n)$$

Question 17

Which of the following best describes the arrangement of chromosomes during metaphase I of meiosis?

Accepted Answer

Homologous pairs (bivalents) align at the metaphase plate.

Question 18

Which syndrome is caused by trisomy of chromosome 21?

Accepted Answer

Down syndrome

Question 19

Which of the following events occurs during anaphase II of meiosis?

Accepted Answer

Sister chromatids separate and move to opposite poles.

Question 20

A cell with the genotype $$YyRr$$ undergoes meiosis. Which mechanism ensures that the alleles for these genes can be inherited in new combinations?

Accepted Answer

Independent assortment and crossing over

Chapter 13: Meiosis – Mechanisms and Significance in Genetic Variation

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