Question 1

Which of the following best describes the role of meiosis in the human life cycle?

Accepted Answer

Meiosis reduces the chromosome number by half in gametes, preventing chromosome doubling after fertilization.

Question 2

A human karyotype shows 46 chromosomes arranged in 23 pairs. What does each pair represent?

Accepted Answer

A homologous pair, with one chromosome from each parent, carrying genes for the same traits.

Question 3

In humans, what is the chromosome number in a sperm cell, and how does it compare to a somatic cell?

Accepted Answer

Sperm cell: $$n=23$$; Somatic cell: $$2n=46$$

Question 4

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They have the same length, centromere position, and staining pattern, but may carry different alleles.

Question 5

A botanist observes a plant species with a multicellular diploid stage (sporophyte) and a multicellular haploid stage (gametophyte). Which type of sexual life cycle does this plant exhibit?

Accepted Answer

Alternation of generations

Question 6

If a dog has a diploid number of $$2n=78$$, how many chromosomes are present in a dog’s gamete?

Accepted Answer

$$n=39$$

Question 7

Which of the following best explains why the number of chromosomes does not correlate with the complexity of an organism?

Accepted Answer

Chromosome number reflects evolutionary history, not genome size or complexity.

Question 8

In the sexual life cycle of most fungi and some protists, which of the following is true?

Accepted Answer

The only diploid stage is the single-celled zygote, which undergoes meiosis immediately.

Question 9

A geneticist is analyzing a human karyotype to screen for congenital disorders. Which stage of the cell cycle are the chromosomes most likely in, and why?

Accepted Answer

Metaphase, because chromosomes are condensed and aligned for easy visualization.

Question 10

Which of the following scenarios would result in a zygote with an abnormal chromosome number?

Accepted Answer

A gamete with $$n=24$$ chromosomes fuses with a gamete with $$n=23$$ chromosomes.

Question 11

Which process ensures that the chromosome number remains constant from one generation to the next in sexually reproducing organisms?

Accepted Answer

Alternation of meiosis and fertilization

Question 12

In plants, what is the correct sequence of events in the alternation of generations?

Accepted Answer

Sporophyte → meiosis → spores → gametophyte → mitosis → gametes → fertilization → zygote → sporophyte

Question 13

A unicellular eukaryote produces gametes under stress, which fuse to form a zygote. The zygote immediately undergoes meiosis to produce new cells. This life cycle is most similar to which group?

Accepted Answer

Fungi and some protists

Question 14

Which of the following statements about the X and Y chromosomes in humans is correct?

Accepted Answer

The X chromosome is larger and contains more genes than the Y chromosome.

Question 15

If a fruit fly has a haploid number of $$n=4$$, what is the diploid number of chromosomes in its somatic cells?

Accepted Answer

$$2n=8$$

Question 16

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

Accepted Answer

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

Question 17

A scientist uses a drug to stimulate mitosis in cultured human cells to prepare a karyotype. Why is this step necessary?

Accepted Answer

To increase the number of cells in metaphase, where chromosomes are most condensed and visible.

Question 18

Which of the following is a fundamental result of all sexual life cycles, regardless of the timing of meiosis and fertilization?

Accepted Answer

Genetic variation among offspring

Question 19

In the analogy of shoes for chromosomes, what does a human haploid cell represent?

Accepted Answer

One shoe from each pair, representing one set of chromosomes

Question 20

Which of the following events occurs during fertilization in humans?

Accepted Answer

Two haploid gametes fuse, restoring the diploid chromosome number.

Fertilization, Meiosis, and Sexual Life Cycles

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