Question 1

Which of the following statements best describes the main difference between Archaea and Bacteria?

Accepted Answer

Archaea possess ether-linked membrane lipids, whereas Bacteria have ester-linked membrane lipids.

Question 2

Carl Woese is best known for which major contribution to microbiology?

Accepted Answer

Proposing the three-domain system based on rRNA sequence analysis.

Question 3

Which of the following is a unique characteristic of Gram-negative bacterial cell walls?

Accepted Answer

Presence of an outer membrane containing lipopolysaccharide (LPS).

Question 4

A scientist is studying a microbe that can fix nitrogen and produce methane. Which domain is this organism most likely from?

Accepted Answer

Archaea

Question 5

Which of the following best explains why RNA is considered a possible candidate for the original genome in early cellular evolution?

Accepted Answer

RNA can catalyze chemical reactions and store genetic information.

Question 6

Which process allows bacteria to directly transfer genetic material through cell-to-cell contact?

Accepted Answer

Conjugation

Question 7

A bacterial cell is placed in a hypertonic environment. Which process will most likely occur?

Accepted Answer

Water will move out of the cell, causing plasmolysis.

Question 8

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

Ligase

Question 9

Which of the following equations correctly represents the calculation of bacterial population after $$n$$ generations, starting with $$N_0$$ cells?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 10

Which structure is found in both Gram-positive and Gram-negative bacteria and is essential for motility?

Accepted Answer

Flagellum

Question 11

A microbe isolated from a hot spring at $$80^\circC is $$most likely classified as:

Accepted Answer

Thermophile

Question 12

Which of the following best describes the function of the ATP Binding Cassette (ABC) transporter?

Accepted Answer

Uses ATP hydrolysis to actively transport substances across the membrane.

Question 13

Which of the following is a major component of the outer membrane of Gram-negative bacteria and is responsible for endotoxic effects?

Accepted Answer

Lipid A

Question 14

Which of the following best describes the process of chemotaxis in bacteria?

Accepted Answer

Movement toward or away from a chemical stimulus by rotating flagella.

Question 15

Which adaptation allows halophiles to survive in high-salt environments?

Accepted Answer

Accumulation of compatible solutes to balance osmotic pressure.

Question 16

Which of the following is NOT a phase in the typical bacterial growth curve?

Accepted Answer

Replication phase

Question 17

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms consist of cells embedded in an extracellular polymeric substance.

Question 18

Which molecule is used in quorum sensing by many Gram-negative bacteria?

Accepted Answer

N-acyl homoserine lactone (AHL)

Question 19

Which of the following is a correct description of the function of single-strand binding proteins during DNA replication?

Accepted Answer

They prevent the separated DNA strands from re-annealing.

Question 20

Which of the following best describes the role of plasmids in bacterial cells?

Accepted Answer

They carry genes that may confer advantages such as antibiotic resistance.

Microbiology Study Guide: Domains of Life, Bacterial Cell Structure, and Microbial Growth

Study Guide - Practice Questions