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 introduce genetic variation through crossing over, independent assortment, and random fusion of gametes.

Question 2

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

Accepted Answer

Prophase I; it increases genetic variation by exchanging genetic material between homologous chromosomes.

Question 3

A human cell with 47 chromosomes is most likely the result of which meiotic error?

Accepted Answer

Nondisjunction, leading to aneuploidy such as trisomy.

Question 4

Which of the following karyotypes would most likely result in Klinefelter syndrome?

Accepted Answer

$$XXY$$

Question 5

In plants exhibiting alternation of generations, which process directly produces haploid gametes?

Accepted Answer

Mitosis of the multicellular haploid stage (gametophyte).

Question 6

A child is born with Down syndrome. Which chromosomal abnormality is most likely present?

Accepted Answer

Trisomy 21, meaning there are three copies of chromosome 21.

Question 7

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

Accepted Answer

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

Question 8

Which event during meiosis is responsible for independent assortment of alleles?

Accepted Answer

Random alignment of tetrads on the metaphase plate during Metaphase I.

Question 9

A woman with Turner syndrome has which of the following chromosomal compositions?

Accepted Answer

$$XO$$

Question 10

If a cell starts meiosis with a diploid number of $$2n = 8$$, how many chromosomes will each daughter cell have at the end of meiosis II?

Accepted Answer

$$n = 4$$

Question 11

Which of the following is a direct result of nondisjunction during meiosis II?

Accepted Answer

Some gametes have an extra chromatid, while others are missing one.

Question 12

Which chromosomal disorder is characterized by a cat-like cry in infants and is caused by a deletion on chromosome 5?

Accepted Answer

Cri du chat syndrome

Question 13

Which hypothesis explains the evolutionary advantage of sexual reproduction in rapidly changing environments?

Accepted Answer

Changing-Environment Hypothesis

Question 14

A researcher observes a multicellular organism whose main life stage is haploid, and only the zygote is diploid. Which type of sexual life cycle does this organism exhibit?

Accepted Answer

Haploid dominant

Question 15

Which of the following best describes the outcome of meiosis compared to mitosis?

Accepted Answer

Meiosis produces four genetically unique haploid cells, while mitosis produces two genetically identical diploid cells.

Question 16

A male patient is found to have an XYY karyotype. Which of the following is a likely characteristic?

Accepted Answer

Increased testosterone levels and possible chronic acne.

Question 17

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

Accepted Answer

Binary fission

Question 18

A plant produces spores by meiosis. What is the ploidy of these spores?

Accepted Answer

Haploid ($$n)$$

Question 19

Which chromosomal abnormality is most likely to result in a female who is phenotypically normal and fertile?

Accepted Answer

Trisomy X ($$XXX)$$

Question 20

A zygote is formed by the union of two gametes. If each gamete contains $$n$$ chromosomes, what is the chromosome number of the zygote?

Accepted Answer

$$2n$$

Meiosis: Mechanisms, Genetic Variation, and Chromosomal Disorders

Guida di studio - Domande di pratica

Study guide - Flashcard