Question 1

Which of the following events occurs during prophase I of meiosis but NOT during mitosis?

Accepted Answer

Homologous chromosomes undergo synapsis and crossing over.

Question 2

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

Accepted Answer

Nondisjunction during meiosis

Question 3

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

Accepted Answer

Crossing over, independent assortment, and random fertilization

Question 4

A karyotype of a patient reveals two X chromosomes and one Y chromosome (47, XXY). Which syndrome does this individual most likely have?

Accepted Answer

Klinefelter syndrome

Question 5

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

Accepted Answer

DNA replication during S phase

Question 6

If a diploid organism has a genome with $$2n = 8$$, how many possible combinations of chromosomes can be produced in its gametes due to independent assortment alone?

Accepted Answer

$$2^4 = 16$

Question 7

Which of the following statements about homologous chromosomes is TRUE?

Accepted Answer

They carry the same genes at the same loci, but may have different alleles.

Question 8

During which phase of meiosis do homologous chromosomes separate, leading to a reduction in chromosome number?

Accepted Answer

Anaphase I

Question 9

A woman is a carrier for a genetic disorder located on the X chromosome. If nondisjunction occurs during meiosis II in her egg cells, which of the following could be a possible outcome for her offspring?

Accepted Answer

A child with monosomy X (Turner syndrome)

Question 10

Which of the following best describes the difference between autosomes and sex chromosomes?

Accepted Answer

Autosomes are chromosomes not directly involved in determining sex, while sex chromosomes determine an individual's sex.

Question 11

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

Accepted Answer

Production of recombinant chromatids

Question 12

A zygote is formed when two gametes fuse. If each gamete is haploid ($$n$$), what is the ploidy of the resulting zygote?

Accepted Answer

Diploid ($$2n)$$

Question 13

Which of the following is NOT a difference between meiosis and mitosis?

Accepted Answer

Meiosis occurs only in somatic cells; mitosis occurs only in gametes.

Question 14

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which the chromosome number is not an exact multiple of the haploid set

Question 15

Which event during meiosis increases genetic variation by creating new combinations of alleles on a single chromosome?

Accepted Answer

Crossing over

Question 16

If a plant species is normally diploid ($$2n = 14) $$but a particular individual is found to have $$21$$ chromosomes, what is the best description of this individual's condition?

Accepted Answer

Polyploidy

Question 17

Which of the following is the correct sequence of events during meiosis I?

Accepted Answer

Synapsis → Crossing over → Independent assortment → Separation of homologous chromosomes

Question 18

Which of the following terms refers to a pair of chromosomes that carry genes for the same traits but may have different alleles?

Accepted Answer

Homologous chromosomes

Question 19

A scientist observes a cell with two sets of chromosomes, each consisting of two sister chromatids, aligned at the metaphase plate. Which phase is this cell most likely in?

Accepted Answer

Metaphase I of meiosis

Question 20

Which of the following best explains why Down syndrome (trisomy 21) occurs?

Accepted Answer

Nondisjunction during meiosis leading to an extra copy of chromosome 21

Meiosis and Sexual Life Cycles: Study Guide

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