Question 1

Which of the following best describes the semiconservative nature of DNA replication?

Accepted Answer

Each new DNA molecule consists of one original strand and one new strand.

Question 2

A bacterial cell is exposed to UV radiation, resulting in a mutation that changes a codon from $$\mathrm{UAC} ($$tyrosine) to $$\mathrm{UAA} ($$stop codon). What type of mutation has occurred?

Accepted Answer

Nonsense mutation

Question 3

Which enzyme is responsible for sealing the gaps between Okazaki fragments during DNA replication?

Accepted Answer

Ligase

Question 4

A patient is treated with hydrogen peroxide, and bubbling is observed at the wound site. Which enzyme produced by bacteria is responsible for this reaction?

Accepted Answer

Catalase

Question 5

Which of the following best explains why endospores are highly resistant to physical and chemical control methods?

Accepted Answer

They have a thick protein coat and dehydrated core.

Question 6

A culture of bacteria is incubated at 4°C and shows optimal growth, but fails to grow at 37°C or 50°C. This organism is best classified as a:

Accepted Answer

Psychrophile

Question 7

Which of the following statements about glycolysis is correct?

Accepted Answer

It produces a net gain of 2 ATP and 2 NADH per glucose molecule.

Question 8

During aerobic respiration, what molecule serves as the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 9

A hospital sterilizes heat-sensitive medical equipment using a gas that alkylates proteins and DNA. Which chemical agent is being used?

Accepted Answer

Ethylene oxide

Question 10

A patient develops an infection after surgery due to improper aseptic technique. What is the term for this type of infection?

Accepted Answer

Healthcare-associated infection (HAI)

Question 11

Which of the following best describes the difference between disinfection and antisepsis?

Accepted Answer

Antisepsis reduces microbial numbers on living tissue; disinfection is used on inanimate objects.

Question 12

A microbe that grows equally well in the presence or absence of oxygen is classified as a:

Accepted Answer

Facultative anaerobe

Question 13

Which of the following is a function of siderophores in microbial virulence?

Accepted Answer

They help bacteria acquire iron from the host.

Question 14

A disease outbreak spreads rapidly across several continents. What is the correct epidemiological term for this event?

Accepted Answer

Pandemic

Question 15

Which of the following best describes the role of a vector in disease transmission?

Accepted Answer

A living organism that transmits pathogens between hosts.

Question 16

Which of the following best explains why biofilms are more resistant to antimicrobial agents than planktonic cells?

Accepted Answer

Biofilms have a protective extracellular matrix that limits penetration of antimicrobials.

Question 17

A bacterial toxin binds to a host cell receptor and is then internalized, disrupting protein synthesis. This is an example of which type of toxin?

Accepted Answer

A-B exotoxin

Question 18

Which of the following best describes the function of ATP synthase in the electron transport chain?

Accepted Answer

It synthesizes ATP from ADP and inorganic phosphate using a proton gradient.

Question 19

A patient is infected with a pathogen that remains dormant in nerve cells and can reactivate years later. What is the term for this type of infection?

Accepted Answer

Latent infection

Question 20

Which of the following best describes the difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP; oxidative phosphorylation uses a proton gradient and ATP synthase.

MCB 2010 Midterm Study Guide: Genetics, Microbial Growth, Metabolism, Epidemiology, and Host-Microbe Interactions

Study Guide - Practice Questions

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