Question 1

Which of the following best explains why meiosis is necessary for sexually reproducing organisms?

Accepted Answer

Meiosis reduces the chromosome number by half, preventing chromosome doubling in each generation.

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 statements about homologous chromosomes is TRUE?

Accepted Answer

They are inherited one from each parent and have genes for the same traits at the same loci.

Question 4

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 homologous chromosomes

Question 5

A karyotype is most useful for which of the following purposes?

Accepted Answer

Visualizing the number and structure of chromosomes in a cell

Question 6

Which of the following genetic disorders is characterized by a monosomy of the sex chromosomes?

Accepted Answer

Turner syndrome

Question 7

If a plant species has a diploid number of $$2n = 18$$, how many chromosomes will be found in its gametes?

Accepted Answer

$$9$$

Question 8

Which of the following events occurs during Anaphase I of meiosis but NOT during Anaphase II?

Accepted Answer

Separation of homologous chromosomes

Question 9

Which process is responsible for the fact that siblings (except identical twins) are genetically unique?

Accepted Answer

Crossing over, independent assortment, and random fertilization

Question 10

A person with the karyotype $$47, XXY$$ would be diagnosed with which syndrome?

Accepted Answer

Klinefelter syndrome

Question 11

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a segment of DNA coding for a trait, while an allele is a variant form of that gene.

Question 12

Which chromosomal structural change involves a segment of a chromosome being reversed end to end?

Accepted Answer

Inversion

Question 13

If nondisjunction occurs during meiosis II, what is the expected outcome in the resulting gametes?

Accepted Answer

Half the gametes will be normal, and half will be abnormal (one with an extra chromosome, one missing a chromosome).

Question 14

Which of the following equations correctly represents the number of possible chromosome combinations due to independent assortment in humans?

Accepted Answer

$$2^{23}$$

Question 15

Which of the following is TRUE regarding the alternation of generations in plants?

Accepted Answer

The sporophyte is diploid and produces haploid spores by meiosis.

Question 16

Which chromosomal abnormality is associated with Down syndrome?

Accepted Answer

Trisomy 21

Question 17

A female with the karyotype $$47, XXX$$ would be classified as which of the following?

Accepted Answer

Poly-X female

Question 18

Which of the following best explains why genetic diversity is important in populations?

Accepted Answer

It increases the likelihood that some individuals will survive environmental changes.

Question 19

Which of the following is NOT a possible result of a chromosomal translocation?

Accepted Answer

A segment of a chromosome is reversed end to end.

Question 20

Is it possible for a person who is biologically female to have a Y chromosome? Explain.

Accepted Answer

Yes, in Swyer syndrome, individuals have an XY karyotype but develop as females due to nonfunctional SRY gene.

Chapter 13: Meiosis and Sexual Life Cycles – Study Guide and Lecture Notes

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