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

$$\textit{Mycobacterium tuberculosis}$$

Question 1

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

Accepted Answer

$$	extit{Mycobacterium tuberculosis}$$

Question 2

Which of the following statements best distinguishes Archaea from Bacteria?

Accepted Answer

Archaea have unique membrane lipids and can survive extreme environments, while Bacteria typically have peptidoglycan cell walls.

Question 3

Why was van Leuwenhoek’s simple microscope considered superior to Hooke’s compound microscope for observing microorganisms?

Accepted Answer

It had a single, high-quality lens that provided greater resolution and clarity.

Question 4

Which scientist is correctly matched with their major contribution to microbiology?

Accepted Answer

Louis Pasteur – disproved spontaneous generation with the swan-neck flask experiment

Question 5

Which unit would be most appropriate to measure the size of a typical bacterial cell?

Accepted Answer

Micrometer ($$\mum)$$

Question 6

Which of the following best describes a key difference between light microscopes and electron microscopes?

Accepted Answer

Electron microscopes use electron beams for much higher resolution than light microscopes, which use visible light.

Question 7

What is the primary function of the blue filter in brightfield microscopy?

Accepted Answer

To decrease the wavelength of light, improving resolution.

Question 8

During the Gram stain procedure, what is the effect of the alcohol decolorizer on Gram-negative bacteria?

Accepted Answer

It dissolves the outer membrane and removes the crystal violet-iodine complex, making the cells colorless.

Question 9

Which type of bacteria can be identified using the acid-fast stain, and what is the key component detected?

Accepted Answer

Mycobacterium species; mycolic acid in the cell wall

Question 10

Which of the following best describes the difference between fimbriae and pili in bacteria?

Accepted Answer

Fimbriae are short and numerous, aiding in attachment; pili are longer and involved in conjugation.

Question 11

What is the main structural difference between Gram-positive and Gram-negative bacterial cell envelopes?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane; Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Question 12

If a bacterial cell loses its cell wall, under which condition is it most likely to survive?

Accepted Answer

In an isotonic solution

Question 13

What does the 'S' in 70S and 80S ribosomes stand for, and why are these values non-additive?

Accepted Answer

S stands for Svedberg unit, a measure of sedimentation rate; the values are non-additive because sedimentation depends on shape and mass, not just size.

Question 14

Which of the following is an example of a bacterial inclusion body and its function?

Accepted Answer

Magnetosome; orientation along magnetic fields

Question 15

Which genera of bacteria are known for producing endospores, and what is the primary function of the endospore?

Accepted Answer

Bacillus and Clostridium; survival under extreme conditions

Question 16

Which of the following media is both selective and differential, and how is it used in the laboratory?

Accepted Answer

MacConkey agar; selects for Gram-negative bacteria and differentiates lactose fermenters

Question 17

During which phase of the bacterial growth curve does the population size remain constant as the rate of cell division equals the rate of cell death?

Accepted Answer

Stationary phase

Question 18

A bacterial culture starts with 500 cells ($$N_i = 500) $$and undergoes 4 generations ($$n = 4). $$Using the formula $$N_f = N_i 	imes 2^n$$, how many cells will be present at the end?

Accepted Answer

$$N_f = 500 	imes 2^4$ = 8,000$$

Question 19

Which of the following is an example of an indirect method for enumerating bacteria?

Accepted Answer

Measuring turbidity with a spectrophotometer

Question 20

Which of the following agents is correctly matched with its category and example?

Accepted Answer

Antiseptic – inhibits growth on living tissue; iodine

Question 21

A disk diffusion plate shows a large zone of inhibition around a disk containing a chemical agent. What does this indicate about the agent?

Accepted Answer

It is bactericidal or highly inhibitory to the bacteria.

Question 22

Which of the following correctly matches a method of microbial control with its effect and a real-world application?

Accepted Answer

Moist heat – coagulates proteins; used for pasteurizing milk

Exam 1 Review: Foundations of Microbiology

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