Question 1

Which of the following best describes the principle behind the Gram stain technique used in microbiology labs?

Accepted Answer

It distinguishes bacteria by differences in cell wall structure, specifically the thickness of peptidoglycan.

Question 2

A student observes a specimen under a compound light microscope using a 40x objective lens and a 10x ocular lens. What is the total magnification?

Accepted Answer

$40 	imes 10 = 400$

Question 3

Which of the following is NOT a function of the bacterial cell wall?

Accepted Answer

Regulating the passage of molecules into and out of the cell

Question 4

During a streak plate technique, what is the primary goal?

Accepted Answer

To isolate individual colonies from a mixed culture

Question 5

Which of the following best explains why viruses are not classified as living organisms?

Accepted Answer

They cannot reproduce independently outside a host cell

Question 6

A microbiologist is testing the effectiveness of a disinfectant using the disk diffusion method. What is the most appropriate way to interpret the results?

Accepted Answer

By measuring the diameter of the zone of inhibition around the disk

Question 7

Which of the following statements about microbial metabolism is correct?

Accepted Answer

Catabolism provides energy and building blocks for anabolism.

Question 8

A patient is diagnosed with a bacterial infection. The lab uses an ELISA test to detect antibodies in the patient's serum. What does a positive result indicate?

Accepted Answer

The patient has antibodies specific to the bacterial pathogen.

Question 9

Which of the following is a correct statement about prions?

Accepted Answer

Prions are infectious proteins that lack nucleic acids.

Question 10

In a bacterial transformation experiment, what is the purpose of using a plasmid containing an antibiotic resistance gene?

Accepted Answer

To select for bacteria that have successfully taken up the plasmid

Question 11

Which of the following best describes the role of epidemiology in public health?

Accepted Answer

It studies the distribution and determinants of diseases in populations.

Question 12

A microbiologist performs a serial dilution and plate count to estimate the number of bacteria in a sample. If 0.1 mL of a $10^{-4}$ dilution yields 50 colonies, what is the original concentration of bacteria per mL?

Accepted Answer

$50 	imes 10^{4} \div 0.1 = 5 	imes 10^{6}$ CFU/mL

Question 13

Which of the following is a key difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus, while prokaryotic cells do not.

Question 14

Which of the following best describes the function of antibodies in the immune response?

Accepted Answer

They bind to antigens and neutralize or mark pathogens for destruction.

Question 15

A scientist is using phase-contrast microscopy to observe live, unstained cells. What is the main advantage of this technique?

Accepted Answer

It allows visualization of internal structures without staining.

Question 16

Which of the following is the correct sequence of events in the lytic cycle of a bacteriophage?

Accepted Answer

Attachment, penetration, biosynthesis, maturation, release

Question 17

A patient is exposed to a bacterial pathogen and develops a fever and inflammation. Which type of immune response is primarily responsible for these symptoms?

Accepted Answer

Non-specific (innate) immune response

Question 18

Which of the following best explains why antibiotics are ineffective against viruses?

Accepted Answer

Viruses do not have metabolic pathways targeted by antibiotics.

Question 19

A water sample is tested for microbial contamination using the membrane filtration method. What is the most likely outcome if coliform bacteria are present?

Accepted Answer

Colonies will grow on selective media, indicating contamination.

Question 20

Which of the following is a correct statement about microbial genetics?

Accepted Answer

Mutations in microbial DNA can lead to antibiotic resistance.

Microbiology Course Syllabus and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards