Question 1

The image above depicts the process of fertilization. Which of the following statements best describes the genetic consequence of fertilization in humans?

Accepted Answer

Fertilization restores the diploid number of chromosomes, resulting in a zygote with $$2n = 46$$ chromosomes.

Question 2

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

Accepted Answer

Genetic variation arises from crossing over, independent assortment, and random fertilization during sexual reproduction.

Question 3

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

Accepted Answer

Crossing over occurs during prophase I and increases genetic variation by exchanging DNA between non-sister chromatids.

Question 4

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

Accepted Answer

Each gamete will contain $$n = 23$$ chromosomes.

Question 5

Which of the following is NOT a source of genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase of mitosis.

Question 6

A cell with a diploid number of $$2n = 8$$ undergoes meiosis. How many different combinations of chromosomes are possible in the gametes due to independent assortment alone?

Accepted Answer

$$2^4 = 16$

Question 7

Which of the following best describes homologous chromosomes?

Accepted Answer

They are pairs of chromosomes, one from each parent, that carry genes for the same traits at the same loci.

Question 8

What is the primary purpose of meiosis in the sexual life cycle?

Accepted Answer

To reduce the chromosome number by half, producing haploid gametes.

Question 9

Which event during meiosis leads to the formation of four genetically unique gametes from a single diploid cell?

Accepted Answer

Crossing over between non-sister chromatids and independent assortment of homologous chromosomes.

Question 10

A geneticist is studying a rare disorder that only appears when both copies of a gene are mutated. Which process ensures that an individual receives one copy of each gene from each parent?

Accepted Answer

Fertilization, which combines haploid gametes from each parent to form a diploid zygote.

Question 11

During metaphase I of meiosis, what is the arrangement of chromosomes, and why is this important?

Accepted Answer

Homologous pairs align at the metaphase plate, allowing for independent assortment and increased genetic variation.

Question 12

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

Accepted Answer

$$2^{23}$$

Question 13

If a mutation occurs during crossing over in meiosis I, which chromatids are most likely to be affected?

Accepted Answer

Non-sister chromatids of homologous chromosomes.

Question 14

Which process is responsible for producing cells that are genetically identical to the parent cell?

Accepted Answer

Mitosis

Question 15

A scientist observes a cell with duplicated chromosomes aligned in pairs at the center of the cell. Which stage of meiosis is being observed?

Accepted Answer

Metaphase I

Meiosis and Sexual Life Cycles: Study Notes for BIO-101

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