Question 1

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

Accepted Answer

Because each child inherits a random combination of chromosomes from each parent due to independent assortment and crossing over during meiosis.

Question 2

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 3

A human somatic cell contains 46 chromosomes. After meiosis, how many chromosomes will each gamete contain?

Accepted Answer

$$n = 23$$

Question 4

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 5

If an organism has a diploid number of 8 ($$2n = 8$$), how many possible combinations of chromosomes can be produced in its gametes by independent assortment alone?

Accepted Answer

$$2^n = 2^4$ = 16$$

Question 6

Which event is unique to meiosis and does NOT occur in mitosis?

Accepted Answer

Synapsis and crossing over between homologous chromosomes.

Question 7

A plant species exhibits alternation of generations. Which of the following correctly describes this life cycle?

Accepted Answer

It includes both multicellular diploid (sporophyte) and multicellular haploid (gametophyte) stages.

Question 8

Which process restores the diploid number of chromosomes in sexually reproducing organisms?

Accepted Answer

Fertilization

Question 9

In humans, how many genetically distinct gametes can be produced by independent assortment alone, ignoring crossing over?

Accepted Answer

$$2^{23}$$ \approx 8,400,000$$

Question 10

Which of the following best describes the evolutionary significance of sexual reproduction?

Accepted Answer

It increases genetic variation, which can be acted upon by natural selection.

Question 11

During which stage of meiosis are homologous chromosomes separated?

Accepted Answer

Anaphase I

Question 12

A mutation occurs in a gene on one chromosome. Which process during sexual reproduction can result in this mutation being passed to offspring?

Accepted Answer

The mutation is present in a gamete that participates in fertilization.

Question 13

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

Accepted Answer

Recombinant chromosomes containing DNA from both parents.

Question 14

Which of the following best describes the difference between asexual and sexual reproduction?

Accepted Answer

Asexual reproduction produces genetically identical offspring, while sexual reproduction produces genetically diverse offspring.

Question 15

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

Accepted Answer

Replication of DNA during mitosis

Question 16

A diploid cell with 10 chromosomes undergoes meiosis. How many chromosomes will each resulting gamete have?

Accepted Answer

$$n = 5$$

Question 17

Which of the following is true regarding the behavior of chromosomes during metaphase I of meiosis?

Accepted Answer

Homologous pairs of chromosomes align at the metaphase plate.

Question 18

Why is it important that meiosis reduces the chromosome number by half in gametes?

Accepted Answer

To maintain a constant chromosome number across generations after fertilization.

Question 19

Which of the following best explains why the products of meiosis are genetically distinct from each other and from the parent cell?

Accepted Answer

Because of independent assortment, crossing over, and random fertilization.

Question 20

In which type of organism is the only diploid stage the single-celled zygote, with no multicellular diploid stage?

Accepted Answer

Most fungi and some protists

Meiosis and Sexual Life Cycles: Genetics, Chromosomes, and Variation

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