Question 1

Which of the following structures is present in all prokaryotic cells but absent in eukaryotic animal cells?

Accepted Answer

Cell wall

Question 2

A scientist is using a compound light microscope with a 10x ocular lens and a 40x objective lens. What is the total magnification being used?

Accepted Answer

$$10 	imes 40 = 400$$

Question 3

Which of the following best describes the function of lipopolysaccharide (LPS) in Gram-negative bacteria?

Accepted Answer

It acts as an endotoxin and contributes to the structural integrity of the outer membrane.

Question 4

Why are acid-fast bacilli not effectively stained by the Gram stain?

Accepted Answer

Their cell wall contains a high concentration of mycolic acids, making them impermeable to the Gram stain.

Question 5

A bacterial culture starts with 3 cells. If the generation time is 2 hours, how many cells will there be after 8 hours? (Assume no cell death.)

Accepted Answer

$$3 	imes 2^4$ = 48$$

Question 6

Which of the following is a function of the bacterial capsule?

Accepted Answer

Protection against phagocytosis

Question 7

Which staining technique is specifically used to observe Mycobacterium species?

Accepted Answer

Acid-fast stain

Question 8

What is the main difference between a Gram-positive and a Gram-negative bacterial cell wall?

Accepted Answer

Gram-positive has a thick peptidoglycan layer; Gram-negative has a thin one and an outer membrane.

Question 9

Which of the following best defines 'normal flora'?

Accepted Answer

Microorganisms that normally reside on or in the human body without causing disease

Question 10

Which of the following is NOT a function of the bacterial cell wall?

Accepted Answer

Protein synthesis

Question 11

A microbiologist wants to observe the detailed internal structure of a bacterial cell. Which microscope should they use and why?

Accepted Answer

Transmission electron microscope, because it can visualize internal ultrastructure at high resolution

Question 12

Which of the following best describes a plasmid?

Accepted Answer

A small, circular piece of DNA found in the cytoplasm of bacteria

Question 13

What is the function of teichoic acids in Gram-positive bacteria?

Accepted Answer

They help anchor the cell wall to the plasma membrane and contribute to cell wall rigidity.

Question 14

Which of the following best describes the arrangement of cocci in chains?

Accepted Answer

Streptococci

Question 15

Which of the following statements about endospores is TRUE?

Accepted Answer

Endospores are highly resistant structures formed by certain bacteria to survive harsh conditions.

Question 16

Which of the following best describes the function of cytoplasmic membrane proteins in bacteria?

Accepted Answer

They function in transport of molecules and signal transduction.

Question 17

Which of the following is the correct binomial nomenclature for the organism commonly known as 'staph'?

Accepted Answer

Staphylococcus aureus

Question 18

Which of the following best describes the purpose of fixing a bacterial smear before staining?

Accepted Answer

To kill the bacteria and adhere them to the slide

Question 19

Which of the following best describes a facultative anaerobe?

Accepted Answer

Can grow with or without oxygen, but grows better with oxygen

Question 20

A microbiologist is comparing the maximum magnification of different microscopes. Which of the following is correct?

Accepted Answer

Light microscope: $$1000	imes$$, Transmission electron microscope: $$100,000	imes$$

Fundamentals of Microbiology: Cell Structure, Classification, and Microscopy

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