Question 1

Which of the following statements best explains why sexual reproduction leads to greater genetic variation in offspring compared to asexual reproduction?

Accepted Answer

Sexual reproduction involves the fusion of gametes from two parents, allowing for the reshuffling of alleles through independent assortment and crossing over.

Question 2

A human somatic cell contains 46 chromosomes. How many chromosomes are present in a human gamete, and what process is responsible for this chromosome number?

Accepted Answer

23 chromosomes; produced by meiosis

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 non-sister chromatids.

Question 4

If a diploid organism has a haploid number $$n = 4$$, how many possible combinations of chromosomes can be produced in its gametes due to independent assortment alone?

Accepted Answer

$$2^4 = 16$

Question 5

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

Accepted Answer

Homologous chromosomes are a pair of chromosomes (one from each parent) with the same genes but possibly different alleles, while sister chromatids are identical copies of a single chromosome joined at the centromere.

Question 6

A plant exhibits an alternation of generations. Which of the following statements is true regarding its life cycle?

Accepted Answer

It has both a multicellular diploid sporophyte and a multicellular haploid gametophyte stage.

Question 7

Which chromosomal abnormality is characterized by the presence of three copies of chromosome 21, and what is the most common risk factor for this condition?

Accepted Answer

Trisomy 21 (Down syndrome); increased maternal age

Question 8

Which of the following events occurs only during meiosis and not during mitosis?

Accepted Answer

Synapsis and crossing over between homologous chromosomes

Question 9

A geneticist observes a chromosome with a segment that has been reversed end to end. What type of chromosomal mutation is this?

Accepted Answer

Inversion

Question 10

Which of the following best explains why asexual reproduction is advantageous in a stable environment?

Accepted Answer

It produces genetically identical offspring that are well-suited to the current environment.

Question 11

A male with the genotype XXY is diagnosed with a chromosomal disorder. Which syndrome does he have, and what is a common physical characteristic?

Accepted Answer

Klinefelter syndrome; underdeveloped testes and some breast development

Question 12

During meiosis, what is the result if nondisjunction occurs during anaphase I?

Accepted Answer

All resulting gametes will have either an extra chromosome or be missing a chromosome.

Question 13

Which formula correctly represents the number of possible chromosome combinations in gametes due to independent assortment, where $$n is $$the haploid number?

Accepted Answer

$$2^n$$

Question 14

Which of the following is NOT a way that sexual reproduction increases genetic variation?

Accepted Answer

Mutations during mitosis

Question 15

A child is born with a deletion on one chromosome, resulting in the loss of several genes. Which of the following best describes this chromosomal abnormality?

Accepted Answer

A segment of the chromosome is missing due to a break at one or both ends.

Question 16

Which of the following best describes the role of the synaptonemal complex during meiosis?

Accepted Answer

It holds homologous chromosomes together tightly during prophase I, facilitating crossing over.

Question 17

In a human karyotype, how many pairs of autosomes and sex chromosomes are present?

Accepted Answer

22 pairs of autosomes and 1 pair of sex chromosomes

Question 18

Which of the following scenarios would most likely result in an individual with Jacob’s syndrome (XYY)?

Accepted Answer

A male inherits an extra Y chromosome due to nondisjunction during sperm formation.

Question 19

Which of the following is a real-world consequence of random fertilization in humans, given that each gamete can have $$8,388,608$$ possible chromosome combinations?

Accepted Answer

The zygote can have more than $$70$$ trillion possible chromosome combinations.

Meiosis and Sexual Life Cycles: Structure, Function, and Genetic Variation

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