Question 1

Which of the following best explains the significance of Louis Pasteur’s S-necked flask experiment?

Accepted Answer

It showed that microorganisms in the air, not spontaneous generation, are responsible for contamination.

Question 2

A scientist is attempting to determine if a specific bacterium causes a new disease. According to Koch’s postulates, which step must be completed after isolating the bacterium from a diseased host?

Accepted Answer

The bacterium must be shown to cause disease when introduced into a healthy host.

Question 3

Which of the following is the correct way to write the scientific name for the bacterium that causes tuberculosis?

Accepted Answer

Mycobacterium tuberculosis

Question 4

During Gram staining, if the decolorizer (alcohol) is omitted, what is the expected result?

Accepted Answer

Both Gram-positive and Gram-negative cells will appear purple.

Question 5

Which bacterial cell shape and arrangement is described by spherical cells in clusters?

Accepted Answer

Staphylococci

Question 6

Acid-fast bacteria are medically challenging because:

Accepted Answer

Their waxy cell wall prevents many antibiotics and disinfectants from entering.

Question 7

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They enable bacteria to survive harsh environmental conditions.

Question 8

Which taxonomic kingdom includes organisms that are multicellular, lack cell walls, and are heterotrophic?

Accepted Answer

Animalia

Question 9

Which of the following statements about DNA replication is correct?

Accepted Answer

DNA polymerase synthesizes new DNA strands in the $$5' \rightarrow 3'$$ direction.

Question 10

Which mechanism of horizontal gene transfer involves the uptake of naked DNA from the environment?

Accepted Answer

Transformation

Question 11

A virus is considered non-living because:

Accepted Answer

It cannot reproduce without a host cell.

Question 12

Which of the following best describes the difference between budding and lysis in viral release?

Accepted Answer

Budding allows enveloped viruses to exit the cell without immediately killing it, while lysis destroys the host cell.

Question 13

Which of the following is a benefit of fermentation for cells?

Accepted Answer

It allows cells to generate ATP without oxygen.

Question 14

Which term describes a pathogen that only causes disease in immunocompromised hosts?

Accepted Answer

Opportunistic pathogen

Question 15

A microbiologist is testing the effectiveness of a disinfectant. If the decimal reduction time ($$D) is 2 $$minutes, how long will it take to reduce a population of $$10^6$$ bacteria to $$10^3$$ bacteria?

Accepted Answer

$$6$$ minutes

Question 16

Which of the following best describes a facultative anaerobe?

Accepted Answer

It can grow with or without oxygen.

Question 17

Which of the following is a characteristic of exotoxins compared to endotoxins?

Accepted Answer

Exotoxins are secreted proteins that can be highly specific in their action.

Question 18

A patient is diagnosed with septic shock. Which category of bacteria is most likely to cause this condition and why?

Accepted Answer

Gram-negative bacteria, because their lipopolysaccharide endotoxin induces severe inflammation.

Question 19

Which of the following best describes the difference between sensitivity and specificity in diagnostic tests?

Accepted Answer

Sensitivity measures the ability to detect true positives, specificity measures the ability to detect true negatives.

MCB 2010C Midterm Study Guide: Microbiology Core Concepts (Chapters 8, 9, 10 Focus)

Study Guide - Practice Questions

Study Guide - Flashcards