Question 1

Which of the following best describes the main contribution of Louis Pasteur to the field of microbiology?

Accepted Answer

He disproved the theory of spontaneous generation through his swan-neck flask experiment.

Question 2

Which of the following statements correctly differentiates prokaryotic from eukaryotic cells?

Accepted Answer

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

Question 3

A scientist is using Koch's postulates to determine if a specific bacterium causes a new disease. Which step must be completed to satisfy the second postulate?

Accepted Answer

The microorganism must be isolated from a diseased organism and grown in pure culture.

Question 4

Which of the following best describes the function of the ribosome in both prokaryotic and eukaryotic cells?

Accepted Answer

Protein synthesis

Question 5

A Gram-negative bacterium is observed under a microscope. Which structural feature is unique to Gram-negative bacteria and has clinical implications for antibiotic resistance?

Accepted Answer

An outer membrane containing lipopolysaccharide (LPS)

Question 6

Which of the following equations correctly represents the calculation of pH from hydrogen ion concentration?

Accepted Answer

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

Question 7

Which of the following best explains why endospores are significant in medical microbiology?

Accepted Answer

Endospores allow bacteria to survive harsh conditions, making infections difficult to eradicate.

Question 8

A patient is diagnosed with a bacterial infection. The laboratory uses the streak plate method to isolate the causative agent. What is the primary purpose of the streak plate method?

Accepted Answer

To obtain isolated colonies from a mixed culture

Question 9

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP serves as the main energy currency, coupling catabolic and anabolic reactions.

Question 10

During glycolysis, glucose is converted into which molecule, and how many net ATP molecules are produced per glucose?

Accepted Answer

Glucose is converted to two pyruvate molecules, producing a net gain of 2 ATP.

Question 11

Which of the following best describes the function of the phospholipid bilayer in the cytoplasmic membrane?

Accepted Answer

It acts as a selective barrier, regulating the movement of substances into and out of the cell.

Question 12

A microbiologist is comparing the flagella of bacteria and eukaryotic cells. Which statement is correct regarding bacterial flagella?

Accepted Answer

Bacterial flagella are made of flagellin and rotate like a propeller.

Question 13

Which of the following best explains the clinical importance of the structure of the Gram-negative cell wall?

Accepted Answer

The outer membrane with lipopolysaccharide (LPS) can trigger strong immune responses and provides resistance to certain antibiotics.

Question 14

Which of the following is a correct description of competitive inhibition in enzyme activity?

Accepted Answer

A molecule similar to the substrate binds to the active site, preventing substrate binding.

Question 15

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

A single bacterial cell divides into two genetically identical daughter cells.

Question 16

A culture of bacteria is growing in a closed system. During which phase of the bacterial growth curve does the rate of cell division equal the rate of cell death?

Accepted Answer

Stationary phase

Question 17

Which of the following best explains why obligate anaerobes are killed by oxygen?

Accepted Answer

They lack enzymes such as superoxide dismutase and catalase to detoxify reactive oxygen species.

Question 18

Which of the following is a direct method that requires incubation for measuring bacterial reproduction?

Accepted Answer

Plate count method (serial dilution and colony counting)

Question 19

Which of the following best describes the endosymbiotic theory?

Accepted Answer

Eukaryotic cells evolved from prokaryotic cells by engulfing smaller prokaryotes that became organelles.

Question 20

Which of the following best describes the function of fermentation in microbial metabolism?

Accepted Answer

Fermentation regenerates NAD$^+$ from NADH, allowing glycolysis to continue in the absence of oxygen.

Microbiology Exam 1 Study Guide: Chapters 1–6

Study Guide - Practice Questions

Study Guide - Flashcards