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 foreign DNA fragment into a bacterial cell, and the cell expresses a new trait. This process is best described as:

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

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 free 3' hydroxyl group

Question 5

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously toward the replication fork, while the lagging strand is synthesized discontinuously away from the fork

Question 6

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this, and why is it considered deleterious?

Accepted Answer

Nonsense mutation; it introduces a premature stop codon, truncating the protein

Question 7

Which of the following processes occurs in the nucleus of eukaryotic cells but not in prokaryotic cells?

Accepted Answer

RNA splicing (removal of introns)

Question 8

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

Accepted Answer

Alternative splicing of pre-mRNA

Question 9

A cell is observed to have chromosomes aligned in homologous pairs at the metaphase plate. Which process is this cell undergoing, and what is the significance?

Accepted Answer

Meiosis I; allows for crossing over and genetic variation

Question 10

Which of the following best explains why telomeres shorten with each round of DNA replication in eukaryotic cells?

Accepted Answer

DNA polymerase cannot add nucleotides to the 5' end of the lagging strand after removal of the RNA primer

Question 11

Which of the following is NOT a source of genetic variation during meiosis?

Accepted Answer

Replication of DNA during interphase

Question 12

Which of the following best describes the flow of genetic information according to the central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 13

Which of the following is true regarding the products of mitosis and meiosis?

Accepted Answer

Mitosis produces two genetically identical diploid cells; meiosis produces four genetically different haploid cells

Question 14

Which of the following is a function of ubiquitin in post-translational gene regulation?

Accepted Answer

Marks proteins for degradation by the proteasome

Question 15

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 16

Which of the following is an example of epigenetic inheritance?

Accepted Answer

Methylation of cytosine bases that is passed to daughter cells

Question 17

Which of the following events occurs during meiosis II but not during meiosis I?

Accepted Answer

Separation of sister chromatids

Question 18

A mutation causes a single nucleotide insertion in a coding region. What is the likely effect on the resulting protein?

Accepted Answer

A frameshift mutation that alters the reading frame

Question 19

Which of the following is a pre-transcriptional control of gene expression?

Accepted Answer

Histone acetylation altering chromatin structure

Question 20

Which of the following signals the start of translation in eukaryotic cells?

Accepted Answer

A start codon ($$	ext{AUG}) on $$the mRNA

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

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