Question 1

Which of the following best explains why random mutations are more likely to be harmful than beneficial to an organism?

Accepted Answer

Random changes in DNA are more likely to disrupt functional sequences than improve them.

Question 2

In the human life cycle, how many rounds of mitosis typically occur before a cell undergoes meiosis to form a gamete in females?

Accepted Answer

$$50$$

Question 3

Which of the following statements about meiosis is correct?

Accepted Answer

Meiosis produces four haploid cells, each with a unique combination of alleles.

Question 4

A heterozygous individual for a gene with alleles $$A ($$dominant) and $$a ($$recessive) will display which phenotype?

Accepted Answer

The phenotype associated with allele $$A.$$

Question 5

Which process during meiosis increases genetic diversity by exchanging DNA between homologous chromosomes?

Accepted Answer

Crossing over during Prophase I

Question 6

In humans, why are males more likely to express X-linked recessive traits?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 7

Which of the following best describes epistasis?

Accepted Answer

One gene masks or modifies the effect of another gene acting downstream in a pathway.

Question 8

A point mutation changes a single nucleotide in a gene. Which of the following outcomes is most likely if the mutation occurs at a splice site?

Accepted Answer

The mRNA may be spliced incorrectly, possibly causing a frameshift and premature stop codon.

Question 9

If two genes are located close together on the same chromosome, which of the following is most likely?

Accepted Answer

They will often be inherited together, unless crossing over occurs between them.

Question 10

Which of the following best explains why bacterial chromosomes do not have telomeres?

Accepted Answer

Bacterial chromosomes are circular, so they do not have ends that require telomeres.

Question 11

Which of the following is a direct consequence of a frameshift mutation in a protein-coding gene?

Accepted Answer

The reading frame of the mRNA is altered, potentially resulting in a nonfunctional protein.

Question 12

Which of the following best describes codominance?

Accepted Answer

Both alleles are expressed equally in the phenotype.

Question 13

A plant with genotype $$PpIi is $$crossed with another $$PpIi$$ plant. If $$I$$ inhibits color and $$P$$ causes purple color, what is the expected phenotypic ratio of the offspring?

Accepted Answer

$$12$$ white : $$3$$ purple : $$1$$ red

Question 14

Which of the following is a function of regulatory domains in the genome?

Accepted Answer

They determine how often mRNA transcripts are made from nearby genes.

Question 15

Which of the following best explains the evolutionary advantage of sexual reproduction?

Accepted Answer

It increases genetic diversity, allowing populations to adapt to changing environments.

Question 16

If a chromosome did not have telomeres, what would happen to it after several rounds of mitosis?

Accepted Answer

It would lose DNA from its ends, leading to loss of genetic information and instability.

Question 17

Which of the following is true about the inheritance of X-linked recessive traits in humans?

Accepted Answer

A male with one recessive allele will express the trait.

Question 18

Which of the following is a likely result of nondisjunction during meiosis?

Accepted Answer

Some gametes will have an abnormal number of chromosomes, leading to disorders such as Down syndrome.

Question 19

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

Genotype is the inherited DNA sequence, which can contribute to the phenotype, the observable traits.

Question 20

Which of the following is a consequence of crossing over during meiosis?

Accepted Answer

It increases genetic diversity by shuffling alleles between homologous chromosomes.

Lecture 20: Inheritance, Evolution, and Cellular Mechanisms

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