Question 1

Which of the following best describes the function of peptidoglycan in bacterial cells?

Accepted Answer

It provides structural support and protects the cell from osmotic lysis.

Question 2

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

Accepted Answer

$$40 	imes 10 = 400$$

Question 3

Which of the following statements about Gram staining is correct?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and appear purple after staining.

Question 4

Which of the following best explains why phase contrast microscopy is advantageous for observing live, unstained cells?

Accepted Answer

It enhances contrast by amplifying differences in refractive index, allowing visualization of internal structures in living cells.

Question 5

A scientist is comparing the resolving power of two microscopes. Microscope A has a resolving power of $$0.2\ \mu m$$ and Microscope B has a resolving power of $$0.5\ \mu m. $$Which statement is correct?

Accepted Answer

Microscope A can distinguish objects that are closer together than Microscope B.

Question 6

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

Accepted Answer

Enhancement of phagocytosis by host immune cells

Question 7

Which of the following best describes the difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus, while prokaryotic cells lack a nucleus.

Question 8

A patient presents with a bacterial infection. The laboratory reports that the bacteria are Gram-negative rods. Which of the following is a likely characteristic of these bacteria?

Accepted Answer

They have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides.

Question 9

Which of the following best explains why ATP is considered the energy currency of the cell?

Accepted Answer

ATP stores energy in its high-energy phosphate bonds, which can be hydrolyzed to release energy for cellular work.

Question 10

Which of the following statements about biofilms is correct?

Accepted Answer

Biofilms are communities of microorganisms attached to a surface and embedded in a self-produced matrix.

Question 11

Which of the following is a correct statement about the Gram stain procedure?

Accepted Answer

The counterstain (safranin) stains Gram-negative cells pink after decolorization.

Question 12

Which of the following best describes the function of phospholipids in the cell membrane?

Accepted Answer

They form a bilayer that acts as a selective barrier, controlling the movement of substances in and out of the cell.

Question 13

A microbiologist observes a bacterium with a single flagellum at one end. What is the correct term for this flagellar arrangement?

Accepted Answer

Monotrichous

Question 14

Which of the following is a correct comparison between the compound light microscope and the electron microscope?

Accepted Answer

The electron microscope uses beams of electrons instead of light, allowing for much higher magnification and resolution.

Question 15

Which of the following best explains why scientific nomenclature is important in microbiology?

Accepted Answer

It provides a universal system for naming organisms, reducing confusion and ensuring clear communication.

Question 16

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

Accepted Answer

Ribosomes synthesize proteins by translating messenger RNA.

Question 17

A scientist is studying a microbe that lacks a nucleus, has a single circular chromosome, and contains 70S ribosomes. To which group does this organism most likely belong?

Accepted Answer

Prokaryotes

Question 18

Which of the following is a correct statement about the function of the bacterial cell wall?

Accepted Answer

It provides structural support and determines the shape of the cell.

Question 19

Which of the following best describes the difference between magnification and resolution in microscopy?

Accepted Answer

Magnification is the increase in size of an image, while resolution is the ability to distinguish two points as separate.

Question 20

Which of the following is a correct statement about the function of pili in bacteria?

Accepted Answer

Pili are involved in attachment to surfaces and in the transfer of genetic material during conjugation.

BIO 22: Foundational Concepts in Microbiology

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