Question 1

Which of the following best explains why Gram-positive bacteria retain the crystal violet stain during the Gram staining procedure?

Accepted Answer

Their thick peptidoglycan layer prevents the crystal violet-iodine complex from being washed out by alcohol.

Question 2

Which experiment provided the strongest evidence against the theory of spontaneous generation?

Accepted Answer

Louis Pasteur's swan-neck flask experiment, which showed that broth remained sterile unless exposed to microorganisms from the air.

Question 3

A patient is diagnosed with a bacterial infection. The bacteria are found to lack a nucleus, have 70S ribosomes, and a cell wall containing peptidoglycan. Which classification best fits these organisms?

Accepted Answer

Bacteria

Question 4

Which of the following best describes the main difference between catabolism and anabolism in microbial metabolism?

Accepted Answer

Catabolism releases energy by breaking down molecules, while anabolism consumes energy to build complex molecules.

Question 5

Which of the following equations correctly represents the net ATP yield from aerobic respiration of one molecule of glucose in prokaryotes?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38ATP$$

Question 6

A microbiologist wants to distinguish between living and dead bacterial cells in a sample. Which staining technique should they use?

Accepted Answer

Viability stain (such as using propidium iodide and SYTO 9)

Question 7

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

Accepted Answer

Prokaryotes have 70S ribosomes, while eukaryotes have 80S ribosomes in their cytoplasm.

Question 8

A hospital outbreak is traced to a contaminated water source. Which mode of infectious disease transmission does this represent?

Accepted Answer

Vehicle transmission

Question 9

Which of the following best describes the mechanism of action of beta-lactam antibiotics such as penicillin?

Accepted Answer

They inhibit peptidoglycan synthesis by binding to penicillin-binding proteins.

Question 10

A scientist uses restriction enzymes and DNA ligase to insert a gene into a plasmid, then introduces the plasmid into E. coli. Which technique is being used?

Accepted Answer

Recombinant DNA technology (gene cloning)

Question 11

Which of the following is a potential ethical concern associated with recombinant DNA technology?

Accepted Answer

Unintended release of genetically modified organisms into the environment

Question 12

Which of the following best describes a mutation?

Accepted Answer

A permanent change in the nucleotide sequence of DNA

Question 13

A patient is prescribed an antibiotic that targets the 70S ribosome. Which type of organism is most likely to be affected?

Accepted Answer

Bacteria

Question 14

Which of the following is NOT a physical method of microbial control?

Accepted Answer

Alcohol disinfection

Question 15

Which of the following best describes the process of horizontal gene transfer by conjugation?

Accepted Answer

Transfer of DNA from one bacterium to another via a pilus

Question 16

A microbiologist is culturing a thermophilic bacterium. Which of the following temperature ranges is most appropriate for optimal growth?

Accepted Answer

$$50^\circ C to$$ $$60^\circ C$$

Question 17

Which of the following statements about viruses is correct?

Accepted Answer

Viruses are obligate intracellular parasites that require a host cell for replication.

Question 18

During an epidemic, the incidence of a disease is measured. Which equation correctly represents incidence rate?

Accepted Answer

$$	ext{Incidence Rate} = \frac{	ext{Number of new cases during a specific period}}{	ext{Population at risk during the same period}} 	imes 100,000$$

Question 19

Which of the following is a reservoir of infectious disease in humans?

Accepted Answer

An asymptomatic carrier

Question 20

A patient develops a bacterial infection after taking a broad-spectrum antibiotic for a viral illness. Which phenomenon does this scenario best illustrate?

Accepted Answer

Antibiotic resistance due to selective pressure on normal flora

Comprehensive Study Notes for Microbiology Final Exam (BIOL 209)

Study Guide - Practice Questions

Study Guide - Flashcards