Question 1

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

Accepted Answer

Mitosis produces two diploid cells, while meiosis produces four haploid cells.

Question 2

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

Accepted Answer

Crossing over occurs during prophase I and increases genetic variation.

Question 3

A cell with a diploid number of $$2n = 8$$ undergoes meiosis. How many chromosomes will each gamete contain after meiosis is complete?

Accepted Answer

$$4$$

Question 4

Which of the following events occurs during anaphase of mitosis but not during anaphase I of meiosis?

Accepted Answer

Sister chromatids separate and move to opposite poles.

Question 5

If nondisjunction occurs during meiosis I, what is the expected chromosomal composition of the resulting gametes?

Accepted Answer

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

Question 6

Which hypothesis explains why sexual reproduction is favored in environments with rapidly evolving pathogens?

Accepted Answer

Changing-environment hypothesis

Question 7

A human cell in G1 phase contains 46 chromosomes. How many DNA molecules are present in the cell after S phase but before mitosis begins?

Accepted Answer

$$92$$

Question 8

Which of the following best describes a bivalent (tetrad) during meiosis?

Accepted Answer

A group of four chromatids formed by the synapsis of two homologous chromosomes.

Question 9

Which process restores the diploid chromosome number in sexually reproducing organisms?

Accepted Answer

Fertilization

Question 10

A geneticist observes that two genes on different chromosomes assort independently during gamete formation. Which law does this observation support?

Accepted Answer

Law of Independent Assortment

Question 11

If a diploid organism has a haploid number $$n = 3$$, how many possible combinations of chromosomes can be produced by independent assortment during meiosis (ignoring crossing over)?

Accepted Answer

$$8$$

Question 12

Which of the following is a direct result of crossing over during meiosis?

Accepted Answer

Formation of genetically unique chromatids

Question 13

A cell undergoes mitosis and produces two daughter cells. Which statement about the genetic content of these daughter cells is correct?

Accepted Answer

They are genetically identical to each other and to the parent cell.

Question 14

Which of the following best explains why children produced by the same parents are genetically different from each other?

Accepted Answer

Independent assortment and crossing over during meiosis create genetic variation.

Question 15

A patient is diagnosed with Down syndrome, which is caused by trisomy 21. Which meiotic error most likely led to this condition?

Accepted Answer

Nondisjunction during meiosis I or II

Question 16

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry the same genes but may have different alleles.

Question 17

Which phase of the cell cycle is characterized by DNA synthesis?

Accepted Answer

S phase

Question 18

In a certain plant species, the diploid number is $$2n = 12. $$After meiosis, how many chromosomes will be present in each gamete?

Accepted Answer

$$6$$

Question 19

Which of the following is a benefit of sexual reproduction according to the purifying selection hypothesis?

Accepted Answer

It reduces the transmission of harmful mutations to offspring.

Mitosis and Meiosis: Cellular Division and Genetic Diversity

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