Question 1

Which of the following is the minimum structural requirement for a virus to be infectious?

Accepted Answer

A protein capsid and nucleic acid

Question 2

A researcher observes clear zones, called plaques, on a bacterial lawn after adding a viral sample. What is the most likely explanation for the formation of these plaques?

Accepted Answer

Lysis of bacterial cells by bacteriophages

Question 3

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

Accepted Answer

The lytic cycle results in host cell lysis, while the lysogenic cycle integrates viral DNA into the host genome.

Question 4

Which of the following is NOT a possible form of genetic material found in viruses?

Accepted Answer

Ribosomal RNA (rRNA)

Question 5

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack nucleic acids.

Question 6

During glycolysis, ATP is produced by which of the following mechanisms?

Accepted Answer

Substrate-level phosphorylation

Question 7

Which of the following best explains why aerobic respiration produces more ATP than fermentation?

Accepted Answer

Aerobic respiration uses the electron transport chain to generate a proton gradient, which drives ATP synthase.

Question 8

Which molecule is regenerated at the end of the citric acid cycle, allowing the cycle to continue?

Accepted Answer

Oxaloacetate

Question 9

In the electron transport chain, what is the immediate source of energy that powers ATP synthase?

Accepted Answer

Proton gradient across the membrane

Question 10

Which of the following best describes the role of NADH and FADH2 in cellular respiration?

Accepted Answer

They donate electrons to the electron transport chain.

Question 11

A facultative anaerobe is best described as an organism that:

Accepted Answer

Can grow with or without oxygen, but grows better with oxygen.

Question 12

Which enzyme catalyzes the first reaction of the Calvin cycle?

Accepted Answer

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO)

Question 13

Which of the following best explains why biofilms are more resistant to antibiotics than planktonic (free-living) bacteria?

Accepted Answer

Biofilms have an extracellular matrix that limits antibiotic penetration and facilitate gene exchange.

Question 14

A patient is infected with a microbe that grows best at human body temperature and neutral pH. How would you classify this organism?

Accepted Answer

Mesophile and neutrophile

Question 15

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation regenerates NAD+ from NADH, allowing glycolysis to continue in the absence of oxygen.

Question 16

Which of the following best describes the difference between halotolerant and halophilic organisms?

Accepted Answer

Halotolerant organisms can survive in high salt but do not require it, while halophilic organisms require high salt for growth.

Question 17

Which of the following equations correctly represents the net ATP yield from aerobic respiration of one molecule of glucose in prokaryotes?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38ATP$$

Question 18

A microorganism is classified as a chemoheterotroph. What does this mean about its energy and carbon sources?

Accepted Answer

It obtains energy from chemicals and carbon from organic compounds.

Question 19

Which of the following best explains why reactive oxygen species (ROS) are dangerous to cells?

Accepted Answer

ROS can damage DNA, proteins, and lipids through oxidation.

Question 20

Which two enzymes are primarily responsible for neutralizing toxic oxygen radicals in aerobic organisms?

Accepted Answer

Superoxide dismutase and catalase

Microbiology Exam 2 Study Guide: Step-by-Step Guidance

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