Question 1

Which of the following statements best describes the concept of biogenesis as supported by Louis Pasteur's swan-neck flask experiment?

Accepted Answer

All life arises from preexisting life, and contamination occurs only when airborne microbes are allowed to enter.

Question 2

A scientist observes that a broth becomes cloudy after 24 hours. According to the scientific method, what is this observation an example of?

Accepted Answer

An observation

Question 3

Which of the following is NOT one of Koch's postulates for linking a microbe to a specific disease?

Accepted Answer

The pathogen must cause disease in all animals, regardless of species.

Question 4

Which of the following best describes the difference between mutualism and commensalism?

Accepted Answer

Mutualism benefits both organisms; commensalism benefits one and leaves the other unaffected.

Question 5

Which of the following is an example of selective media used in the laboratory?

Accepted Answer

MacConkey agar

Question 6

A patient develops a chronic infection on a catheter. Which property of biofilms most likely contributes to the persistence of this infection?

Accepted Answer

Biofilms enhance antibiotic tolerance and immune evasion.

Question 7

Which of the following best describes the binomial nomenclature format for naming microbes?

Accepted Answer

Genus capitalized, species lowercase, both italicized.

Question 8

Which of the following is a role of normal microbiota in human health?

Accepted Answer

Colonization resistance against pathogens through competition and bacteriocin production.

Question 9

Which of the following is the correct order of taxonomic hierarchy from broadest to most specific?

Accepted Answer

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Question 10

Which of the following is a function of a streak plate technique in microbiology?

Accepted Answer

To mechanically dilute a mixed culture and obtain isolated colonies.

Question 11

Which structural stain would you use to visualize bacterial capsules, and what is the principle behind it?

Accepted Answer

Capsule stain; uses negative stain with India ink or nigrosin to detect capsules.

Question 12

Which of the following is a plausible consequence of improper aseptic technique in the laboratory?

Accepted Answer

Contamination of cultures, environment, and experimenter.

Question 13

Which of the following is an example of how microbes impact industry?

Accepted Answer

Fermentation in bread, cheese, and yogurt production.

Question 14

Which of the following is a correct statement about prokaryotic cells?

Accepted Answer

Prokaryotic cells have circular, free-floating DNA and reproduce by binary fission.

Question 15

A strain of E. coli is designated O157:H7. What does this designation indicate?

Accepted Answer

It is a genetic variant or subtype within the species.

Question 16

Which of the following is a plausible healthcare implication of biofilms?

Accepted Answer

Biofilms increase chronic/recurrent infections on medical devices.

Question 17

Which of the following best describes the role of Ignaz Semmelweis in healthcare history?

Accepted Answer

He introduced handwashing with chlorinated lime, reducing puerperal fever.

Question 18

Which of the following is a correct example of a scientific law?

Accepted Answer

A descriptive generalization about how nature behaves, often mathematical, such as gas laws.

Question 19

Which of the following is a correct application of differential media?

Accepted Answer

Differential media show metabolic differences, such as lactose fermentation turning colonies pink.

Question 20

Which of the following is a plausible reason why some pathogens cannot be linked to a disease using Koch's postulates?

Accepted Answer

Some pathogens are polymicrobial and ethical constraints prevent human testing.

Microbiology Learning Objectives: Key Concepts and Study Guide

Study Guide - Practice Questions