Question 1

Which of the following best describes the role of meiosis in the sexual life cycle, as shown in the first image?

Accepted Answer

Meiosis produces haploid gametes, ensuring chromosome number is halved before fertilization restores diploidy.

Question 2

During which phase of meiosis does crossing over occur, and what is its significance as shown in the second image?

Accepted Answer

Crossing over occurs during Prophase I and increases genetic diversity by exchanging DNA between homologous chromosomes.

Question 3

Based on the third image, what is the principle of independent assortment and how does it contribute to genetic variation?

Accepted Answer

Independent assortment occurs during Metaphase I, allowing homologous chromosomes to align randomly, resulting in different combinations of maternal and paternal chromosomes in gametes.

Question 4

Referencing the fourth image, what is the chromosome number in the daughter cells at the end of meiosis II if the original cell was diploid ($$2n$$)?

Accepted Answer

Each daughter cell is haploid ($$n).$$

Question 5

According to the fifth image, what is the result of nondisjunction during meiosis I?

Accepted Answer

Half the gametes will have an extra chromosome, and half will be missing one.

Question 6

The sixth image shows a karyotype with three copies of chromosome 21. What is the genetic condition, and what is its cause?

Accepted Answer

Down syndrome, caused by trisomy 21 due to nondisjunction.

Question 7

In the seventh image, which stage of cell division is depicted, and what does it indicate about the chromosome content of the resulting cells?

Accepted Answer

End of meiosis I; resulting cells are haploid but still have duplicated chromosomes.

Question 8

A diploid organism has $$2n = 34$$ chromosomes. How many chromatids are present in a germ cell during the S phase of meiosis?

Accepted Answer

$$68$$

Question 9

If a mutation eliminated crossing over during meiosis, what would be the most likely outcome for the population?

Accepted Answer

Genetic diversity would decrease, as homologous chromosomes would not exchange genetic material.

Question 10

Why are siblings from the same parents genetically unique (except for identical twins)?

Accepted Answer

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

Question 11

If nondisjunction occurs during meiosis II in the egg, and the egg with 24 chromosomes is fertilized by a normal sperm, what will be the chromosome number in the resulting zygote?

Accepted Answer

$$47$$

Question 12

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis involves one cell division and produces identical cells; meiosis involves two divisions and produces genetically diverse cells.

Question 13

Why does meiosis have two rounds of cell division?

Accepted Answer

To reduce the chromosome number by half and then separate sister chromatids.

Question 14

Which of the following best explains why Down syndrome (trisomy 21) is more common than other autosomal trisomies?

Accepted Answer

Chromosome 21 is small and extra copies are more compatible with life.

Question 15

Which of the following events does NOT contribute to genetic diversity in sexually reproducing organisms?

Accepted Answer

DNA replication during S phase of mitosis.

Question 16

If each human gamete can produce approximately $$8 	imes 10^6$ combinations of chromosomes due to independent assortment, how does random fertilization affect the total possible zygotic combinations?

Accepted Answer

It multiplies the combinations between gametes from both parents, greatly increasing genetic diversity.

Question 17

Which of the following best defines a haploid cell?

Accepted Answer

A cell with one set of chromosomes ($$n).$$

Question 18

What is the main function of germ cells in the sexual life cycle?

Accepted Answer

To undergo meiosis and produce gametes for sexual reproduction.

Question 19

Why doesn’t crossing over occur during mitosis?

Accepted Answer

Because homologous chromosomes do not pair up during mitosis.

Question 20

If homologous chromosomes fail to separate during anaphase I of meiosis, what is the likely outcome for the resulting gametes?

Accepted Answer

Half will have an extra chromosome, and half will lack one.

Comprehensive Study Guide: Meiosis, Genetic Diversity, and Chromosome Behavior

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