Question 1

Which of the following statements best explains why viruses are considered acellular?

Accepted Answer

They are composed of a core of nucleic acid surrounded by a protein coat and cannot reproduce independently.

Question 2

A scientist discovers a microorganism that thrives in hot springs at 90°C and has no peptidoglycan in its cell wall. Which domain does this organism most likely belong to?

Accepted Answer

Archaea

Question 3

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

Accepted Answer

They are dormant, highly resistant structures formed in response to adverse conditions.

Question 4

During Gram staining, why do Gram-negative bacteria appear pink after the procedure?

Accepted Answer

Their outer membrane is dissolved by alcohol, allowing safranin to stain the cells.

Question 5

Which of the following equations correctly represents the calculation of pH?

Accepted Answer

$pH = -\log_{10} [H^+]$

Question 6

A bacterial culture is placed in a solution with a higher solute concentration than inside the cell. What is the most likely outcome for the bacterial cells?

Accepted Answer

The cells will shrink due to water loss (plasmolysis).

Question 7

Which of the following best describes the process of oxidative phosphorylation in prokaryotes?

Accepted Answer

ATP is generated using energy released from electrons passing through the electron transport chain in the plasma membrane.

Question 8

A patient is diagnosed with tuberculosis. Which staining technique would be most appropriate to identify the causative agent in a sputum sample?

Accepted Answer

Acid-fast stain

Question 9

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy required for a reaction to occur.

Question 10

A bacterial cell is placed in a hypotonic solution. What is the most likely result if the cell wall is damaged by lysozyme?

Accepted Answer

The cell will burst due to osmotic lysis.

Question 11

Which of the following best explains why penicillin is more effective against Gram-positive bacteria than Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria lack an outer membrane, allowing penicillin to inhibit peptidoglycan synthesis more effectively.

Question 12

Which of the following is a correct statement about the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 13

A culture medium contains yeast extract, peptone, and glucose, but the exact chemical composition is unknown. This medium is best described as:

Accepted Answer

Complex medium

Question 14

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

Accepted Answer

The end product of a pathway allosterically inhibits an enzyme that acts early in the pathway.

Question 15

Which of the following equations correctly calculates the total number of bacterial cells after $n$ generations, starting from a single cell?

Accepted Answer

$	ext{Total cells} = 2^n$

Question 16

A microbiologist wants to isolate a bacterium that can grow in the presence of high salt concentrations. Which type of medium should she use?

Accepted Answer

Selective medium

Question 17

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

Accepted Answer

It protects the cell from phagocytosis and helps in attachment to surfaces.

Question 18

Which of the following best describes the role of NAD+ in cellular metabolism?

Accepted Answer

It serves as an electron carrier, accepting electrons during redox reactions.

Question 19

A patient is treated for a bacterial infection with an antibiotic that inhibits protein synthesis by binding to the 50S ribosomal subunit. Which of the following antibiotics is most likely being used?

Accepted Answer

Erythromycin

Question 20

Which of the following best explains why biofilms are often resistant to antibiotics?

Accepted Answer

Biofilms provide a protective environment where bacteria can share nutrients and shelter from harmful factors.

Microbiology Study Notes: Chapters 1–8 (History, Chemistry, Cell Structure, Microscopy, Metabolism, Growth, Control, Genetics)

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