Question 1

Which of the following best describes the outcome of Louis Pasteur's experiment disproving spontaneous generation?

Accepted Answer

Sterile broth remained free of microorganisms unless exposed to contaminated air.

Question 2

Which of the following statements about prokaryotic cell components is CORRECT?

Accepted Answer

Prokaryotes have a nucleoid region instead of a true nucleus.

Question 3

A Gram-negative cell is exposed to penicillin. What is the most likely outcome and why?

Accepted Answer

The cell will be less susceptible because penicillin targets peptidoglycan, which is less accessible in Gram-negative cells.

Question 4

Which phase of the bacterial growth curve is characterized by rapid cell division and exponential increase in cell number?

Accepted Answer

Log (exponential) phase

Question 5

A researcher is culturing bacteria in a closed system. After a period of rapid growth, the number of viable cells plateaus. What is the most likely explanation?

Accepted Answer

Cell division rate equals cell death rate due to nutrient depletion and waste accumulation.

Question 6

Which of the following is a correct sequence of steps for a Gram stain procedure?

Accepted Answer

Crystal violet, iodine, alcohol decolorizer, safranin

Question 7

Which of the following best explains how UV light damages bacterial DNA?

Accepted Answer

UV light induces thymine dimers, disrupting DNA replication.

Question 8

A patient is diagnosed with a viral infection. Which of the following features distinguishes enveloped viruses from non-enveloped viruses?

Accepted Answer

Enveloped viruses acquire their membrane from the host cell during budding.

Question 9

Which of the following is a function of RNA polymerase in prokaryotic transcription?

Accepted Answer

It synthesizes RNA from a DNA template.

Question 10

Which of the following best describes the role of the ELISA test in microbiology?

Accepted Answer

It detects the presence of specific antigens or antibodies using enzyme-linked reactions.

Question 11

A patient receives a vaccine containing inactivated virus. Which type of immunity is primarily induced?

Accepted Answer

Artificially acquired active immunity

Question 12

Which of the following pathogens is most commonly associated with causing strep throat?

Accepted Answer

Streptococcus pyogenes

Question 13

Which of the following is a correct formula for calculating the generation time ($g$) in a bacterial culture?

Accepted Answer

$g = \frac{t}{n}$

Question 14

A Kirby-Bauer disk diffusion test shows a large zone of inhibition around an antibiotic disk. What does this indicate?

Accepted Answer

The bacteria are susceptible to the antibiotic.

Question 15

Which of the following is a major difference between eukaryotic and prokaryotic gene expression?

Accepted Answer

Prokaryotes couple transcription and translation in the cytoplasm.

Question 16

Which of the following is a correct equation for calculating the dilution factor ($DF$) in a serial dilution?

Accepted Answer

$DF = \frac{	ext{volume of sample}}{	ext{total volume}}$

Question 17

Which of the following is a key feature of Koch's postulates?

Accepted Answer

The suspected pathogen must be isolated and grown in pure culture.

Question 18

A patient is exposed to hepatitis B virus and develops antibodies. Which type of immunity is this?

Accepted Answer

Naturally acquired active immunity

Question 19

Which of the following best describes the mechanism of action of penicillin?

Accepted Answer

Disrupts cell wall synthesis by inhibiting transpeptidase enzymes.

Question 20

Which of the following is a correct formula for calculating the number of cells ($N$) after $n$ generations, starting with $N_0$ cells?

Accepted Answer

$N = N_0 	imes 2^n$

BIO 420 Microbiology: Comprehensive Study Guide for Lecture and Laboratory Exams

Study Guide - Practice Questions

Study Guide - Flashcards