Question 1

Which of the following best describes the difference between a diploid and a haploid cell in humans?

Accepted Answer

A diploid cell contains two sets of chromosomes (2n = 46), while a haploid cell contains one set (n = 23).

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 by exchanging DNA between homologous chromosomes.

Question 3

If an organism has a diploid number of 6 (2n = 6), how many different combinations of chromosomes are possible in its gametes due to independent assortment?

Accepted Answer

$$2^3 = 8$

Question 4

Which of the following events occurs in meiosis I but not in meiosis II?

Accepted Answer

Separation of homologous chromosomes

Question 5

A human cell in metaphase I of meiosis contains how many chromosomes and chromatids?

Accepted Answer

46 chromosomes, each consisting of two sister chromatids (total 92 chromatids)

Question 6

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

Accepted Answer

Replication of DNA during S phase

Question 7

In the alternation of generations observed in plants, what is the function of the sporophyte?

Accepted Answer

To produce haploid spores by meiosis

Question 8

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry genes controlling the same inherited characters but may have different alleles.

Question 9

A mutation occurs in a gene located on a chromosome. What is the most direct result of this mutation in terms of genetic variation?

Accepted Answer

It creates a new allele of that gene.

Question 10

Which of the following best explains why siblings produced by the same parents are genetically different from each other (except for identical twins)?

Accepted Answer

Independent assortment, crossing over, and random fertilization create unique combinations of alleles in each offspring.

Question 11

During which stage of meiosis are cohesins cleaved along the chromosome arms, and what is the result?

Accepted Answer

Anaphase I; homologous chromosomes separate

Question 12

A zygote is formed by the fusion of two gametes. If each gamete has $$8.4 	imes 10^6$ possible chromosome combinations, how many possible diploid combinations can result from fertilization?

Accepted Answer

$$(8.4 	imes 10^6$) 	imes (8.4 	imes 10^6$) = 7.1 	imes 10$$^{13}$$

Question 13

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically unique haploid cells.

Question 14

Which of the following best describes the process and outcome of synapsis during prophase I?

Accepted Answer

Homologous chromosomes pair up and exchange genetic material, resulting in recombinant chromosomes.

Question 15

In a plant exhibiting alternation of generations, which process directly produces gametes?

Accepted Answer

Mitosis in the gametophyte

Question 16

Which of the following statements about the products of meiosis is correct?

Accepted Answer

Each of the four daughter cells is haploid and genetically distinct from the parent cell and from each other.

Question 17

Which of the following best explains why only diploid cells can undergo meiosis?

Accepted Answer

Meiosis requires homologous pairs of chromosomes, which are only present in diploid cells.

Question 18

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

Accepted Answer

Each gamete receives a random mix of maternal and paternal chromosomes.

Question 19

A cell with 2n = 8 undergoes meiosis. How many chromosomes will each daughter cell have at the end of meiosis II?

Accepted Answer

4

Meiosis, Chromosome Behavior, and Genetic Variation

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