Q: A yeast cell has a DNA content of 24 fg in G1 phase. After S phase, the DNA content is 48 fg. If 1 fg of DNA equals $$9.78 \times 10^5$ base pairs, how many base pairs are synthesized during S phase?

$$24 \times 9.78 \times 10^5$ = 2.3472 \times 10^7$ base pairs

Q: A scientist observes that after meiosis II, four yeast cells each have 12 fg of DNA. If the haploid yeast genome is $$1.1736 \times 10^7$ base pairs, what is the conversion factor used?

$$1 \text{ fg} = 9.78 \times 10^5$ base pairs

Question 1

Which of the following best explains why meiosis, but not mitosis, leads to increased genetic diversity in sexually reproducing organisms?

Accepted Answer

Meiosis includes crossing over and independent assortment, which shuffle genetic material.

Question 2

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

Accepted Answer

Crossing over occurs during Prophase I, increasing genetic variation among gametes.

Question 3

A yeast cell has a DNA content of 24 fg in G1 phase. After S phase, the DNA content is 48 fg. If 1 fg of DNA equals $$9.78 	imes 10^5$ base pairs, how many base pairs are synthesized during S phase?

Accepted Answer

$$24 	imes 9.78 	imes 10^5$ = 2.3472 	imes 10^7$ base pairs

Question 4

Which of the following events occurs in meiosis but NOT in mitosis?

Accepted Answer

Synapsis of homologous chromosomes

Question 5

If a human cell with 46 chromosomes undergoes meiosis, how many chromosomes will each resulting gamete contain?

Accepted Answer

23

Question 6

A mutation prevents the formation of chiasmata during meiosis. What is the most likely consequence for gamete formation?

Accepted Answer

Homologous chromosomes may not separate properly during Anaphase I, leading to abnormal gametes.

Question 7

Which statement correctly compares the outcomes of mitosis and meiosis?

Accepted Answer

Mitosis produces two genetically identical diploid cells; meiosis produces four genetically diverse haploid cells.

Question 8

During which phase of meiosis is the chromosome number reduced from diploid to haploid?

Accepted Answer

Meiosis I

Question 9

If a yeast cell's DNA content drops from 48 fg to 12 fg during meiosis, what does this indicate about the cell's ploidy?

Accepted Answer

The cell has transitioned from diploid to haploid.

Question 10

Which mechanism ensures that each gamete receives a unique combination of alleles during meiosis?

Accepted Answer

Independent assortment of homologous chromosomes during Metaphase I

Question 11

A scientist observes that after meiosis II, four yeast cells each have 12 fg of DNA. If the haploid yeast genome is $$1.1736 	imes 10^7$ base pairs, what is the conversion factor used?

Accepted Answer

$$1 	ext{ fg} = 9.78 	imes 10^5$ base pairs

Question 12

Which of the following best describes the role of cohesion proteins during meiosis?

Accepted Answer

They hold sister chromatids together until Anaphase II.

Question 13

If a mutation caused DNA replication to occur before both meiosis I and meiosis II, what would be the likely outcome?

Accepted Answer

Gametes would have double the normal amount of DNA.

Question 14

Which of the following is a direct result of the random alignment of homologous chromosomes during Metaphase I?

Accepted Answer

Each gamete receives a different combination of maternal and paternal chromosomes.

Question 15

A cell is observed with homologous chromosomes paired and chiasmata visible. Which stage is this cell in?

Accepted Answer

Prophase I of meiosis

Question 16

Which of the following best explains why sister chromatids are not genetically identical after meiosis I?

Accepted Answer

Crossing over between non-sister chromatids during Prophase I exchanges genetic material.

Question 17

In a laboratory experiment, yeast cells are induced to undergo meiosis. At 7.5 hours, DNA content drops from 48 fg to 25 fg. What cellular event most likely explains this observation?

Accepted Answer

Homologous chromosomes separate during Anaphase I.

Question 18

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

Accepted Answer

Mitosis includes synapsis and crossing over; meiosis does not.

Question 19

If nondisjunction occurs during Anaphase I of meiosis, what is the most likely result?

Accepted Answer

Some gametes will have an extra chromosome, and some will be missing one.

Question 20

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

Accepted Answer

Fertilization

Meiosis and Chromosome Number Reduction: Study Guide

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