Question 1

Which of the following best describes the function of the operator in a bacterial operon?

Accepted Answer

It is a segment of DNA that acts as a switch, controlling the access of RNA polymerase to the genes.

Question 2

In the trp operon, what happens when tryptophan is present in high concentrations?

Accepted Answer

Tryptophan acts as a corepressor, activating the repressor and blocking transcription.

Question 3

Which of the following equations correctly represents the relationship between cAMP, CRP, and the lac operon activation?

Accepted Answer

$$cAMP + CRP \rightarrow$$ active complex that enhances lac operon transcription

Question 4

Which of the following is a key difference between inducible and repressible operons?

Accepted Answer

Inducible operons are usually off and can be turned on, while repressible operons are usually on and can be turned off.

Question 5

What is the effect of histone acetylation on gene expression?

Accepted Answer

It relaxes chromatin structure, increasing gene expression.

Question 6

Which structure is shown in the fourth image, and what is its biological significance?

Accepted Answer

A nucleosome; it packages DNA and regulates gene accessibility.

Question 7

Alternative RNA splicing allows for:

Accepted Answer

The production of multiple proteins from a single gene.

Question 8

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

They bind to mRNA and either degrade it or block its translation.

Question 9

A mutation in the ras gene can lead to cancer because:

Accepted Answer

It causes continuous cell division by keeping the signaling pathway permanently active.

Question 10

Which of the following is an example of epigenetic inheritance?

Accepted Answer

DNA methylation patterns passed to daughter cells during cell division.

Question 11

What is the primary function of tumor-suppressor genes such as p53?

Accepted Answer

They prevent uncontrolled cell growth by regulating the cell cycle and promoting apoptosis.

Question 12

Which process ensures that all tissues and organs of an organism are in their characteristic places during development?

Accepted Answer

Pattern formation controlled by molecular cues called positional information.

Question 13

Which of the following mechanisms can convert a proto-oncogene into an oncogene?

Accepted Answer

Gene amplification, point mutation, chromosomal translocation, or epigenetic modification.

Question 14

What is the role of the CRP-cAMP complex in the regulation of the lac operon?

Accepted Answer

It acts as an activator, increasing the rate of transcription when glucose is scarce.

Question 15

Which of the following best explains why not all genes are expressed in every cell of a multicellular organism?

Accepted Answer

Differential gene expression allows cells to specialize and perform unique functions.

Question 16

Which of the following is a function of small interfering RNAs (siRNAs)?

Accepted Answer

They guide the degradation of complementary mRNA, silencing gene expression.

Question 17

In the context of cancer, what is the 'double whammy' that results from a mutation in the p53 gene?

Accepted Answer

Loss of cell cycle arrest and failure to initiate apoptosis in damaged cells.

Question 18

Which of the following best describes the process of determination in embryonic cells?

Accepted Answer

The process by which a cell becomes committed to a specific fate.

Question 19

Which of the following is a likely result of high concentrations of bicoid protein in a developing Drosophila embryo?

Accepted Answer

Development of anterior structures at the site of high bicoid concentration.

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