Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A scientist isolates a nucleic acid from a virus and finds it contains uracil but no thymine. Which type of nucleic acid is this most likely to be?

Accepted Answer

Single-stranded RNA

Question 3

During transcription in eukaryotic cells, which enzyme is primarily responsible for synthesizing mRNA from a DNA template?

Accepted Answer

RNA polymerase

Question 4

Given the DNA sequence $$5'	ext{-}ATGCGTACG-3'$$, what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{-}AUGCGUACG-3'$$

Question 5

Which of the following best describes the function of a promoter in gene expression?

Accepted Answer

It is the site where RNA polymerase binds to initiate transcription.

Question 6

A point mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA}. $$What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 7

Which of the following statements about the lac operon in E. coli is correct?

Accepted Answer

It is an inducible operon that is activated in the presence of lactose.

Question 8

Which of the following best explains the role of noncoding RNAs such as miRNA and siRNA in gene expression?

Accepted Answer

They bind to mRNA to inhibit its translation or promote its degradation.

Question 9

In molecular cloning, which sequence of steps is correct for inserting a gene of interest into a plasmid vector?

Accepted Answer

Restriction endonuclease cuts DNA, ligase joins DNA fragments, plasmid is introduced into bacteria.

Question 10

A researcher wants to amplify a specific DNA segment from a small blood sample. Which technique should they use, and what is the main enzyme involved?

Accepted Answer

PCR; DNA polymerase

Question 11

Which of the following best defines a transgenic organism?

Accepted Answer

An organism that contains DNA from another species.

Question 12

Which of the following statements about viruses is correct?

Accepted Answer

Viruses require a host cell to replicate and lack cellular structure.

Question 13

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome, remaining dormant for several generations. What is this integrated viral DNA called?

Accepted Answer

Prophage

Question 14

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle allows viral DNA to persist in the host genome.

Question 15

Which enzyme is responsible for synthesizing cDNA from an mRNA template in the laboratory?

Accepted Answer

Reverse transcriptase

Question 16

A retrovirus differs from other viruses because it:

Accepted Answer

Uses reverse transcriptase to synthesize DNA from its RNA genome.

Question 17

Which of the following is a correct example of Darwin's logic of natural selection?

Accepted Answer

Individuals with traits better suited to the environment are more likely to survive and reproduce.

Question 18

Which of the following best describes the role of differential gene expression in multicellular organisms?

Accepted Answer

It allows different cell types to express different sets of genes, leading to cell specialization.

Question 19

A patient is diagnosed with a prion disease. Which of the following best describes the infectious agent responsible?

Accepted Answer

A misfolded protein that can induce other proteins to misfold.

Question 20

A mutation in the operator region of the trp operon prevents the repressor from binding. What is the most likely result?

Accepted Answer

The operon will be constitutively expressed, and tryptophan will be synthesized even when it is abundant.

Final Exam Review Guidance: Gene Expression, Operons, Biotechnology, Viruses, and Evolution

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