Question 1

Which of the following best explains why offspring produced by sexual reproduction are genetically different from their parents and from each other?

Accepted Answer

Because sexual reproduction involves the random fusion of gametes, independent assortment of chromosomes, and crossing over during meiosis.

Question 2

A horticulturalist wants to propagate an orchid with a unique combination of traits. Which method should they use to ensure all offspring have the same traits as the parent, and why?

Accepted Answer

Asexual reproduction, because it produces clones genetically identical to the parent.

Question 3

In humans, how many possible combinations of chromosomes can result from independent assortment during gamete formation? Use $$n=23$$ for the haploid number.

Accepted Answer

$$2^{23}$$, or about 8.4 million combinations

Question 4

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

Accepted Answer

Pairing of homologous chromosomes and crossing over

Question 5

A human cell with 46 chromosomes undergoes meiosis. How many chromosomes will each resulting gamete contain?

Accepted Answer

23

Question 6

If a mutation occurs in a gene located at a specific locus on a chromosome, what is the most direct consequence for the organism?

Accepted Answer

A new allele is created, which may be passed to offspring if present in gametes.

Question 7

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

Accepted Answer

Homologous chromosomes are inherited from each parent and may have different alleles, while sister chromatids are identical copies formed after DNA replication.

Question 8

In a species with a diploid number of $$2n=8$$, how many possible chromosome combinations can result from independent assortment during meiosis?

Accepted Answer

$$2^4 = 16$

Question 9

Which process ensures that the chromosome number of a species remains constant across generations?

Accepted Answer

Alternation of meiosis and fertilization

Question 10

A yeast cell has a DNA content of 24 fg in G1 phase. After S phase, the DNA content is 48 fg. After meiosis II, what is the expected DNA content per cell?

Accepted Answer

12 fg

Question 11

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

Accepted Answer

Formation of recombinant chromosomes with new combinations of maternal and paternal alleles

Question 12

In the alternation of generations life cycle of plants, which process produces haploid spores?

Accepted Answer

Meiosis in the sporophyte

Question 13

If a human zygote undergoes mitosis, what will be the chromosome number in each resulting somatic cell?

Accepted Answer

46

Question 14

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

Accepted Answer

Replication of DNA during mitosis

Question 15

A certain fungus spends most of its life cycle as a haploid organism. Which event restores the diploid state in this organism?

Accepted Answer

Fertilization

Question 16

If a mutation creates a new allele in a population, what is the evolutionary significance of this event?

Accepted Answer

It increases genetic diversity, providing raw material for natural selection.

Question 17

Which of the following statements about karyotypes is correct?

Accepted Answer

A karyotype is an ordered display of condensed chromosomes arranged in pairs, useful for detecting chromosomal abnormalities.

Question 18

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 organismal complexity.

Question 19

If maternal and paternal chromatids have the same two alleles for every gene, what is the effect of crossing over during meiosis?

Accepted Answer

Crossing over will not increase genetic variation because the exchanged segments are identical.

Question 20

A diploid organism has a haploid number $$n=10. $$How many genetically distinct gametes can it produce due to independent assortment alone?

Accepted Answer

$$2^{10} = 1024$

Meiosis and Sexual Life Cycles: Genetic Variation and Evolution

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