Question 1

Which of the following mechanisms is the original source of genetic variation in a population?

Accepted Answer

Mutations in DNA

Question 2

A diploid organism has a haploid number $$n=4. $$According to the formula $$2^n$$, how many possible combinations of chromosomes can result from independent assortment during meiosis?

Accepted Answer

$$16$$

Question 3

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

Accepted Answer

Prophase I; it increases genetic diversity by creating recombinant chromosomes

Question 4

If a species has a diploid number $$2n=10$$, how many possible chromosome combinations can be produced in its gametes by independent assortment alone?

Accepted Answer

$$32$$

Question 5

Which of the following best explains why sexual reproduction is considered evolutionarily advantageous despite its higher energy cost compared to asexual reproduction?

Accepted Answer

It generates genetic diversity, increasing the likelihood of survival in changing environments

Question 6

In humans, each gamete contains one of about $$8.4$$ million possible chromosome combinations due to independent assortment. Considering random fertilization, approximately how many possible diploid combinations can result in a human zygote (ignoring crossing over)?

Accepted Answer

$$70$$ trillion

Question 7

A researcher observes that after meiosis, all recombinant chromatids in an organism are genetically identical to the parental chromatids. What is the most likely explanation?

Accepted Answer

Maternal and paternal chromatids had the same alleles for every gene

Question 8

Which of the following scenarios would result in the greatest genetic variation among offspring, assuming no crossing over occurs?

Accepted Answer

A species with $$2n=46$$ chromosomes

Question 9

Bdelloid rotifers are unique among animals because they:

Accepted Answer

Increase genetic diversity by incorporating foreign DNA during suspended animation

Question 10

Which statement best describes the role of crossing over in meiosis?

Accepted Answer

It produces new combinations of alleles by exchanging genetic material between homologous chromosomes

Question 11

If a mutation occurs in a gene during gamete formation, what is the most likely evolutionary consequence if the mutation is beneficial?

Accepted Answer

It may increase in frequency in the population through natural selection

Question 12

Which process is responsible for the random orientation of homologous chromosome pairs at the metaphase plate during meiosis I?

Accepted Answer

Independent assortment

Question 13

Darwin and Mendel both contributed to our understanding of evolution. Which statement best summarizes their contributions?

Accepted Answer

Darwin recognized the importance of heritable variation, and Mendel explained the mechanism of inheritance

Question 14

A scientist is studying two populations: one reproduces sexually, the other asexually. Which population is more likely to adapt rapidly to a changing environment, and why?

Accepted Answer

The sexual population, because sexual reproduction generates greater genetic diversity

Question 15

Which of the following best describes the relationship between mutations and alleles?

Accepted Answer

Mutations create new versions of genes, known as alleles

Question 16

If a human gamete with a novel combination of alleles due to crossing over is fertilized, what is the most likely outcome for the resulting zygote?

Accepted Answer

The zygote will have a unique genetic makeup, different from both parents

Question 17

Which of the following is NOT a mechanism that contributes to genetic variation in sexually reproducing populations?

Accepted Answer

Mitosis

Question 18

A fruit fly has $$2n=8$$ chromosomes, while a grasshopper has $$2n=46. If no $$crossing over occurs, which species will have more possible chromosome combinations in its gametes, and why?

Accepted Answer

Grasshopper, because the number of combinations is $$2^n$$ and $$n is $$larger

Question 19

Which of the following best explains why offspring produced by sexual reproduction are not identical to their parents?

Accepted Answer

Meiosis and fertilization shuffle alleles, creating new combinations

Question 20

If a human chromosome pair undergoes three crossover events during prophase I, what is the effect on genetic variation?

Accepted Answer

It increases genetic variation by producing more recombinant chromatids

Genetic Variation in Sexual Life Cycles and Its Evolutionary Significance

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