Question 1

Which of the following best describes the function of a polysome in bacterial cells?

Accepted Answer

A complex of multiple ribosomes simultaneously translating a single mRNA molecule.

Question 2

Which of the following statements about B-lactam antibiotics is correct?

Accepted Answer

They are produced by fungi and inhibit bacterial cell wall biosynthesis.

Question 3

A bacterial strain is exposed to an antibiotic, and a small subpopulation survives without acquiring genetic resistance. This phenomenon is best described as:

Accepted Answer

Microbial persistence

Question 4

Which of the following is a key difference between constitutively expressed genes and regulated genes?

Accepted Answer

Constitutively expressed genes are always transcribed, while regulated genes are transcribed in response to environmental or cellular signals.

Question 5

In the regulation of the arginine biosynthesis operon, what happens when arginine is abundant in the cell?

Accepted Answer

Arginine acts as a co-repressor, enabling the repressor protein to bind the operator and block transcription.

Question 6

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A process where bacteria communicate using chemical signals to coordinate group behaviors based on population density.

Question 7

Which of the following statements about the CRISPR system in prokaryotes is correct?

Accepted Answer

It provides adaptive immunity by storing fragments of foreign DNA and using Cas proteins to target and cut matching sequences.

Question 8

A scientist is using blue/white screening to identify recombinant plasmids. Which result indicates a successful insertion of foreign DNA into the vector?

Accepted Answer

White colonies, because the insertion disrupts the lacZ gene, preventing $$eta-$$galactosidase production.

Question 9

During generalized transduction, which of the following events occurs?

Accepted Answer

A bacteriophage accidentally packages host bacterial DNA and transfers it to another bacterium.

Question 10

Which of the following best explains why prions are unique infectious agents?

Accepted Answer

They are composed solely of misfolded protein and lack nucleic acids.

Question 11

Which of the following is a major challenge when expressing eukaryotic genes in bacterial cells during molecular cloning?

Accepted Answer

Bacteria cannot remove introns from eukaryotic pre-mRNA.

Question 12

In oxygenic photosynthesis, what is the primary electron donor and what is the main product released as a result?

Accepted Answer

Water ($$H_2O) is $$the electron donor, and oxygen ($$O_2) is $$released.

Question 13

Which of the following statements about fermentation is correct?

Accepted Answer

ATP is generated by substrate-level phosphorylation, and fermentation products are produced to regenerate NAD$$^+.$$

Question 14

A wastewater treatment plant must reduce the BOD of its effluent. What does BOD stand for, and why is it important?

Accepted Answer

Biochemical Oxygen Demand; it measures the amount of oxygen required by microorganisms to decompose organic matter.

Question 15

Which of the following best describes the mutualistic relationship between legume plants and Rhizobia bacteria?

Accepted Answer

The plant provides carbon compounds to the bacteria, and the bacteria fix atmospheric nitrogen ($$N_2) $$into ammonia ($$NH_3) $$for the plant.

Question 16

Which of the following is a key feature of negative regulation of gene expression in bacteria?

Accepted Answer

A repressor protein binds to the operator to block transcription.

Question 17

Which of the following best describes the difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction can transfer any gene from the donor, while specialized transduction transfers only specific genes near the prophage site.

Question 18

Which of the following statements about viroids is correct?

Accepted Answer

Viroids are small, circular RNA molecules that infect plants.

Question 19

During the Calvin Cycle in autotrophic bacteria, what happens to $$CO_2$$?

Accepted Answer

$$CO_2 is $$reduced and incorporated into organic molecules such as glucose.

Question 20

Which of the following best explains why yeast produces ethanol even when oxygen is available (the Crabtree effect)?

Accepted Answer

High glucose concentrations cause yeast to favor fermentation over respiration, leading to ethanol production.

MICR 301 Exam 2 Study Guide: Molecular Information Flow, Regulation, Genetics, Viruses, Antimicrobials, Phototrophy, Fermentation, and Microbial Ecology

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