Question 1

Which of the following best describes the bonds that stabilize the double helix structure of DNA?

Accepted Answer

Hydrogen bonds between complementary nitrogenous bases and phosphodiester bonds in the backbone

Question 2

A scientist introduces a plasmid containing an antibiotic resistance gene into a bacterial culture. After exposure, some bacteria survive and express the resistance gene. This is an example of which process?

Accepted Answer

Transformation

Question 3

Which of the following statements correctly distinguishes DNA from RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 4

Which of the following is a key difference between prokaryotic and eukaryotic cells?

Accepted Answer

Prokaryotes lack a nucleus; eukaryotes have a nucleus.

Question 5

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand, and what does it require to begin synthesis?

Accepted Answer

DNA polymerase; requires an RNA primer and a template strand

Question 6

If a mutation occurs during DNA replication and is not corrected, which of the following is the most likely consequence?

Accepted Answer

The mutation will be inherited by all daughter cells derived from that cell.

Question 7

Where does transcription occur in a eukaryotic cell, and what is the final product?

Accepted Answer

Nucleus; pre-mRNA

Question 8

Which of the following best describes the role of telomeres in eukaryotic chromosomes?

Accepted Answer

They protect chromosome ends from degradation during replication.

Question 9

Which of the following is the correct sequence of events in gene expression in eukaryotes?

Accepted Answer

Transcription $$\rightarrow$$ RNA processing $$\rightarrow$$ Translation

Question 10

A eukaryotic gene contains both introns and exons. What happens to these regions during mRNA processing?

Accepted Answer

Introns are spliced out, and exons are joined together to form mature mRNA.

Question 11

Which type of mutation is most likely to result in a nonfunctional protein?

Accepted Answer

Nonsense mutation

Question 12

Which of the following is a post-transcriptional control of gene expression in eukaryotes?

Accepted Answer

Alternative splicing of pre-mRNA

Question 13

Epigenetic inheritance refers to:

Accepted Answer

Heritable changes in gene expression that do not involve changes to the DNA sequence

Question 14

Which of the following best describes the difference between meiosis and mitosis?

Accepted Answer

Meiosis produces four genetically different haploid cells; mitosis produces two identical diploid cells.

Question 15

During which phase of meiosis do homologous chromosomes separate, and what is the ploidy of the resulting cells?

Accepted Answer

Meiosis I; haploid

Question 16

Which of the following is a major source of genetic variation during meiosis?

Accepted Answer

Crossing over during prophase I

Question 17

A DNA sequence is 5'-ATG CCG TAA-3'. What is the corresponding mRNA sequence produced during transcription?

Accepted Answer

5'-AUG CCG UAA-3'

Question 18

Which of the following mechanisms can silence gene expression post-transcriptionally?

Accepted Answer

RNA interference (RNAi)

Question 19

Which of the following best describes the function of ubiquitin in eukaryotic cells?

Accepted Answer

It marks proteins for degradation by the proteasome.

Question 20

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this, and what is the likely effect on the protein?

Accepted Answer

Nonsense mutation; results in premature termination of translation

Molecular Genetics and Cell Division: DNA Structure, Gene Expression, and Meiosis

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