Question 1

Which of the following statements best describes a virus?

Accepted Answer

An acellular agent that replicates only inside living cells and lacks metabolic machinery.

Question 2

Which bacterial shape is correctly matched with its description?

Accepted Answer

Spirals: bacteria with a twisted or corkscrew shape

Question 3

What is the main difference between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and stain purple.

Question 4

Which of the following is NOT a phase in the bacterial growth curve?

Accepted Answer

Photosynthetic phase

Question 5

A patient presents with fever and shock after a Gram-negative bacterial infection. Which toxin is most likely responsible for these symptoms?

Accepted Answer

Endotoxin (lipopolysaccharide)

Question 6

Which of the following is a characteristic of fungi that distinguishes them from bacteria?

Accepted Answer

Fungi are eukaryotic and possess membrane-bound organelles.

Question 7

Which of the following best describes the role of normal flora in the human body?

Accepted Answer

Normal flora compete with pathogenic microorganisms and help maintain health.

Question 8

Which of the following is a common route of viral transmission?

Accepted Answer

All of the above

Question 9

Which of the following equations best represents exponential bacterial growth during the log phase?

Accepted Answer

$$N_t = N_0$ 	imes 2$$^{n}$$

Question 10

A child in a developing country presents with abdominal discomfort and worms in the feces. Which microorganism is most likely responsible?

Accepted Answer

Ascaris lumbricoides

Question 11

Which of the following is a defining feature of protozoa?

Accepted Answer

They are single-celled eukaryotes that may reproduce sexually or asexually.

Question 12

Which of the following is a correct statement about exotoxins?

Accepted Answer

Exotoxins are proteins actively secreted by bacteria.

Question 13

Which of the following is a real-world example of a disease caused by a protozoan?

Accepted Answer

Malaria

Question 14

Which of the following is NOT a function of the bacterial capsule?

Accepted Answer

Production of ATP

Question 15

Which of the following best explains why viruses are considered acellular?

Accepted Answer

They lack organelles and do not carry out metabolic processes independently.

Question 16

Which of the following is a common misconception about Gram staining?

Accepted Answer

Gram staining can be used to identify all types of microorganisms, including viruses.

Question 17

Which of the following is a correct statement about helminths?

Accepted Answer

Helminths are parasitic worms that can infect humans and cause diseases such as ascariasis.

Question 18

Which of the following is a plausible consequence of disrupting normal flora with antibiotics?

Accepted Answer

Overgrowth of pathogenic microorganisms due to loss of competition

Question 19

Which of the following is a correct statement about the chain of infection?

Accepted Answer

Transmission requires a source, a mode of transmission, and a susceptible host.

Question 20

Which of the following is a correct application of the concept of commensals?

Accepted Answer

Commensals benefit from the host without causing harm.

Microbiology: Types, Structure, and Pathogenicity of Microorganisms

Study Guide - Practice Questions