Question 1

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

Accepted Answer

Homologous chromosomes are inherited from each parent, while sister chromatids are identical copies formed during DNA replication.

Question 2

A human cell containing 22 autosomes and an X chromosome is:

Accepted Answer

A haploid gamete, which could be either an egg or a sperm.

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 a diploid organism has a haploid number $$n = 8$$, how many possible combinations of chromosomes can be produced by independent assortment during meiosis?

Accepted Answer

$$2^8 = 256$

Question 5

Which of the following statements about meiosis and mitosis is correct?

Accepted Answer

Meiosis produces four haploid cells, while mitosis produces two diploid cells.

Question 6

A karyotype is useful for which of the following purposes?

Accepted Answer

Visualizing the number and structure of chromosomes in a cell.

Question 7

In the human life cycle, what is the chromosome number of the zygote immediately after fertilization?

Accepted Answer

$$2n = 46$$

Question 8

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

Accepted Answer

Replication of DNA during S phase of the cell cycle.

Question 9

In plants and some algae, the alternation of generations includes:

Accepted Answer

Both a diploid sporophyte and a haploid gametophyte multicellular stage.

Question 10

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

Accepted Answer

Alignment of homologous pairs at the metaphase plate.

Question 11

A mutation occurs in a gene that codes for a protein involved in DNA repair. What is a possible evolutionary consequence of this mutation?

Accepted Answer

It may increase genetic variation by allowing more mutations to accumulate.

Question 12

Which of the following best explains why offspring from sexual reproduction are genetically unique?

Accepted Answer

They inherit a unique combination of alleles due to independent assortment, crossing over, and random fertilization.

Question 13

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

Question 14

If a human egg (n = 23) is fertilized by a sperm with an abnormal number of chromosomes (n = 24), what will be the chromosome number in the resulting zygote?

Accepted Answer

$$2n = 47$$

Question 15

Which process is responsible for the separation of homologous chromosomes?

Accepted Answer

Anaphase I of meiosis

Question 16

A scientist observes a cell with 46 chromosomes undergoing division. After the first meiotic division, how many chromosomes will each daughter cell contain?

Accepted Answer

23

Question 17

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

Accepted Answer

Formation of recombinant chromosomes

Question 18

Why is sexual reproduction considered advantageous in changing environments?

Accepted Answer

It increases genetic variation, allowing populations to adapt to new conditions.

Question 19

Which of the following best describes the role of cohesins during meiosis?

Accepted Answer

They hold sister chromatids together until anaphase II.

Question 20

If a mutation prevents the formation of the synaptonemal complex during meiosis, which process would be directly affected?

Accepted Answer

Crossing over between homologous chromosomes

Meiosis, Chromosome Inheritance, and Genetic Variation

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