Question 1

Which of the following best explains why offspring produced by sexual reproduction are genetically different from their parents?

Accepted Answer

Because meiosis and fertilization shuffle alleles through independent assortment, crossing over, and random fertilization.

Question 2

A human somatic cell contains 46 chromosomes. How many chromosomes are present in a human gamete?

Accepted Answer

23

Question 3

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 4

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

$$2^4 = 16$

Question 5

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

Accepted Answer

Pairing of homologous chromosomes and crossing over

Question 6

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

Accepted Answer

5

Question 7

Which of the following best describes the difference between homologous chromosomes and sister chromatids?

Accepted Answer

Sister chromatids are identical copies formed by DNA replication; homologous chromosomes are similar but not identical, each inherited from a different parent.

Question 8

In humans, how many different possible chromosome combinations can result from independent assortment during gamete formation? (Assume $$n = 23)$$

Accepted Answer

$$2^{23}$$

Question 9

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

Accepted Answer

Replication of DNA during S phase

Question 10

A plant species exhibits alternation of generations. Which of the following statements is TRUE regarding its life cycle?

Accepted Answer

It alternates between multicellular haploid and multicellular diploid stages.

Question 11

Which of the following is a direct result of the process of synapsis during prophase I of meiosis?

Accepted Answer

Formation of recombinant chromosomes due to crossing over

Question 12

A geneticist observes a cell with chromosomes aligned in pairs at the metaphase plate. Which stage of meiosis is being observed?

Accepted Answer

Metaphase I

Question 13

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

Accepted Answer

Because only diploid cells have homologous pairs of chromosomes that can be separated.

Question 14

If a sperm cell containing an abnormal number of chromosomes fertilizes a normal egg, what is the most likely result?

Accepted Answer

The zygote will have an abnormal chromosome number, potentially leading to genetic disorders.

Question 15

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

Accepted Answer

Each daughter cell is haploid and genetically unique.

Question 16

A mutation occurs in a gene located on a chromosome. Which of the following best describes how this mutation can be passed to the next generation?

Accepted Answer

The mutation must occur in a gamete-producing cell and be incorporated into a gamete.

Question 17

Which of the following is a unique event to meiosis and does NOT occur in mitosis?

Accepted Answer

Synapsis and crossing over between homologous chromosomes

Question 18

If a species has a haploid number of $$n = 6$$, how many different chromosome combinations are possible in its gametes due to independent assortment?

Accepted Answer

$$2^6 = 64$

Question 19

Which of the following best describes the role of random fertilization in genetic variation?

Accepted Answer

It increases genetic variation by allowing any sperm to fuse with any egg, resulting in a zygote with a unique combination of alleles.

Question 20

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.

Meiosis and Sexual Life Cycles: Study Notes (Campbell Biology, Chapter 13)

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