Q: Which of the following equations correctly represents the net reaction of glycolysis for one molecule of glucose?

$$\text{Glucose} + 2\ \text{ADP} + 2\ \text{P}_i + 2\ \text{NAD}^+ \rightarrow 2\ \text{Pyruvic acid} + 2\ \text{ATP} + 2\ \text{NADH} + 2\ \text{H}^+$$

Question 1

Which microscopy technique would be most appropriate for visualizing the three-dimensional surface structure of a bacterial biofilm attached to a medical implant, and why?

Accepted Answer

Scanning acoustic microscopy, because it uses sound waves to detect surface features and is especially useful for cells attached to surfaces.

Question 2

A microbiologist is preparing a bacterial smear for Gram staining. Which of the following steps must be performed before staining, and what is its primary purpose?

Accepted Answer

Fixation, to attach the bacteria to the slide and preserve their structure.

Question 3

During the Gram stain procedure, what is the main reason Gram-negative bacteria appear pink or red at the end of the process?

Accepted Answer

Their thin peptidoglycan layer and outer membrane allow the crystal violet-iodine complex to be washed out during decolorization, so they take up the safranin counterstain.

Question 4

Which of the following best describes the function of a bacterial capsule?

Accepted Answer

It helps prevent desiccation, aids in attachment to surfaces, and can protect against phagocytosis.

Question 5

A scientist observes a bacterium with several flagella located at one end of the cell. What is the correct term for this flagellar arrangement?

Accepted Answer

Lophotrichous

Question 6

Which of the following statements correctly compares Gram-positive and Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan wall with teichoic acids, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharide.

Question 7

Which of the following best explains why enzymes are essential for microbial metabolism?

Accepted Answer

They lower the activation energy required for reactions, allowing metabolic processes to proceed rapidly at cellular temperatures.

Question 8

A bacterial cell is exposed to a competitive inhibitor of an essential enzyme. What is the most likely effect on the enzyme's activity, and how can this inhibition be overcome?

Accepted Answer

The inhibitor occupies the active site, reducing enzyme activity; increasing substrate concentration can overcome the inhibition.

Question 9

Which of the following equations correctly represents the net reaction of glycolysis for one molecule of glucose?

Accepted Answer

$$	ext{Glucose} + 2\ 	ext{ADP} + 2\ 	ext{P}_i + 2\ 	ext{NAD}^+ ightarrow 2\ 	ext{Pyruvic acid} + 2\ 	ext{ATP} + 2\ 	ext{NADH} + 2\ 	ext{H}^+$$

Question 10

A mutation in a bacterium prevents the formation of peptide cross-links in its cell wall. Which of the following would most likely result from this mutation?

Accepted Answer

The cell wall would be structurally weaker and more susceptible to osmotic lysis.

Question 11

Which of the following best describes the difference between substrate-level phosphorylation and oxidative phosphorylation in ATP production?

Accepted Answer

Substrate-level phosphorylation transfers a phosphate group directly from a phosphorylated substrate to ADP, while oxidative phosphorylation uses energy from electron transport to generate ATP.

Question 12

A bacterial cell is placed in a solution containing an acidic dye such as eosin. What is the expected staining result, and why?

Accepted Answer

The background will be stained, while the bacterial cells remain colorless, because acidic dyes are repelled by the negatively charged cell surface.

Question 13

Which of the following is a function of teichoic acids in Gram-positive bacteria?

Accepted Answer

They help regulate the movement of cations and contribute to antigenic specificity.

Question 14

A patient sample is stained using the acid-fast method. Red cells are observed against a blue background. What does this indicate about the sample?

Accepted Answer

The sample contains acid-fast bacteria, such as Mycobacterium, which retain the red carbolfuchsin stain due to their waxy cell wall.

Question 15

Which of the following best describes the role of NAD$$^+ in $$microbial metabolism?

Accepted Answer

It acts as an electron carrier, accepting electrons during catabolic reactions and becoming reduced to NADH.

Question 16

A bacterium is observed to move toward a source of glucose in its environment. Which term best describes this behavior, and what structure is primarily responsible?

Accepted Answer

Chemotaxis, mediated by flagella.

Question 17

Which of the following statements about prokaryotic and eukaryotic cells is correct?

Accepted Answer

Prokaryotic cells lack a membrane-enclosed nucleus and usually have a single circular chromosome.

Question 18

Which of the following best explains the function of feedback inhibition in a metabolic pathway?

Accepted Answer

The end-product of the pathway binds allosterically to the first enzyme, decreasing its activity and preventing overproduction.

Question 19

Which of the following is true regarding the structure and function of bacterial ribosomes?

Accepted Answer

They are the site of protein synthesis and are found in the cytoplasm of all prokaryotic cells.

Microscopy, Prokaryotic Cell Structure, and Microbial Metabolism: Study Notes for Microbiology

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