Question 1

Which of the following statements best describes the main structural difference between Gram-positive and Gram-negative bacteria as revealed by the Gram stain?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and lack an outer membrane.

Question 2

A patient presents with a severe sore throat and is diagnosed with a Streptococcus infection. Which of the following features is most likely to contribute to the pathogenicity of Streptococcus species?

Accepted Answer

Production of a capsule that inhibits phagocytosis

Question 3

Which of the following bacteria is most likely to be found in the intestines of humans as a beneficial microbe, but can also cause disease if it enters the urinary tract?

Accepted Answer

Escherichia coli

Question 4

Which of the following Archaea would most likely be found in a hot spring with a temperature of $$80^\circC $$and a pH of 2?

Accepted Answer

Thermoacidophiles

Question 5

A microbiologist observes a bacterium with a spiral shape and flexible cell wall under the microscope. Which group does this organism most likely belong to?

Accepted Answer

Spirochetes

Question 6

Which of the following is a unique feature of cyanobacteria compared to most other prokaryotes?

Accepted Answer

Ability to perform oxygenic photosynthesis

Question 7

Which of the following protists is responsible for causing malaria in humans, and what is the vector for this disease?

Accepted Answer

Plasmodium; transmitted by Anopheles mosquitoes

Question 8

Which of the following statements correctly distinguishes eukaryotic cells from prokaryotic cells?

Accepted Answer

Eukaryotic cells contain membrane-bound organelles, including a nucleus.

Question 9

A patient is diagnosed with African sleeping sickness. Which organism is responsible for this disease, and what is its mode of transmission?

Accepted Answer

Trypanosoma; transmitted by tsetse fly

Question 10

Which of the following best describes the structure and function of fungal hyphae?

Accepted Answer

Thread-like filaments that collectively form the mycelium and absorb nutrients

Question 11

Which of the following statements about viruses is correct?

Accepted Answer

Viruses are obligate intracellular parasites that lack cellular structure.

Question 12

During the lytic cycle of a bacteriophage, which of the following events occurs?

Accepted Answer

The host cell is lysed, releasing new viral particles.

Question 13

Which of the following is a characteristic of enveloped viruses that distinguishes them from non-enveloped viruses?

Accepted Answer

They acquire a lipid bilayer from the host cell membrane during release.

Question 14

A latent virus can remain dormant in host cells for years before reactivating. Which of the following is an example of a disease caused by a latent virus?

Accepted Answer

Herpes simplex virus causing cold sores

Question 15

Which of the following viruses is classified as a retrovirus and is associated with the development of AIDS?

Accepted Answer

HIV (Human Immunodeficiency Virus)

Question 16

Which of the following best defines a prion?

Accepted Answer

An infectious protein that causes neurodegenerative diseases

Question 17

A sudden increase in the number of cases of a disease in a specific geographic area is best described as:

Accepted Answer

An epidemic

Question 18

Which of the following is a correct pairing of a disease and its vector?

Accepted Answer

West Nile virus; Culex mosquito

Question 19

Which of the following best explains the connection between viruses and cancer?

Accepted Answer

Some viruses can insert oncogenes or activate host oncogenes, leading to uncontrolled cell growth.

Question 20

A patient is diagnosed with botulism after eating improperly canned food. Which bacterial genus is responsible, and what unique structure allows it to survive harsh conditions?

Accepted Answer

Clostridium; endospores

Microbiology Study Guide: Prokaryotes, Eukaryotes, and Viruses (Chapters 11–13)

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