Question 1

Which of the following statements best explains why Gram-negative bacteria are generally more resistant to antibiotics such as penicillin than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane containing lipopolysaccharides that protect against antibiotics.

Question 2

A scientist isolates a microorganism from a thermal spring with the following characteristics: unicellular, no peptidoglycan in the cell wall, branched membrane lipids, and growth at temperatures above 100°C. To which domain does this organism most likely belong?

Accepted Answer

Archaea

Question 3

Which of the following correctly matches the microbial cell type with a unique structural feature?

Accepted Answer

Eukaryote – membrane-bound organelles

Question 4

A Gram stain is performed on a bacterial sample. After the alcohol wash, some cells appear purple and others appear pink. What is the most likely explanation for this observation?

Accepted Answer

The sample contains both Gram-positive and Gram-negative bacteria.

Question 5

Which of the following best describes the evolutionary significance of prokaryotes?

Accepted Answer

Prokaryotes appeared approximately 3.5 billion years ago and are the most abundant organisms on Earth.

Question 6

Which of the following is a correct statement about the cell wall composition of the three domains of life?

Accepted Answer

Eukaryotic plant cells have cell walls made of cellulose.

Question 7

A patient is infected with a bacterium that stains pink after a Gram stain. Which of the following is true about this bacterium?

Accepted Answer

It has an outer membrane containing lipopolysaccharides.

Question 8

Which of the following best explains why prokaryotes can thrive in extreme environments such as salt lakes and thermal springs?

Accepted Answer

They have specialized membrane lipids and unique metabolic pathways.

Question 9

Which of the following is a function of the bacterial cell wall?

Accepted Answer

It maintains cell shape and prevents bursting in hypotonic environments.

Question 10

Which of the following is a correct pairing of bacterial shape and arrangement?

Accepted Answer

Staphylococci – spherical bacteria in clusters

Question 11

Which of the following statements about the Gram stain procedure is correct?

Accepted Answer

Gram-positive bacteria retain the crystal violet dye due to their thick peptidoglycan layer.

Question 12

Which of the following is a unique feature of Archaea compared to Bacteria?

Accepted Answer

Branched membrane lipids attached to glycerol by ether linkages

Question 13

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

Accepted Answer

It is a polysaccharide that forms the main component of the bacterial cell wall.

Question 14

Which of the following is NOT a characteristic of prokaryotic cells?

Accepted Answer

Presence of a membrane-bound nucleus

Question 15

Which of the following is a correct statement about the three-domain system of classification?

Accepted Answer

It divides all life into Bacteria, Archaea, and Eukarya based on genetic relatedness of ribosomal RNA.

Question 16

Which of the following is a real-world application of genetically modified bacteria?

Accepted Answer

Protecting crops from pests and freezing

Question 17

A researcher discovers a unicellular organism with a circular chromosome, no membrane-bound organelles, and a cell wall containing peptidoglycan. Which domain does this organism belong to?

Accepted Answer

Bacteria

Question 18

Which of the following best explains why some bacteria can survive harsh conditions such as extreme heat or desiccation?

Accepted Answer

They form endospores that are highly resistant to environmental stress.

Question 19

Which of the following is a correct comparison between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.

Prokaryotes and Microbial Diversity: Structure, Classification, and Cell Walls

Study Guide - Practice Questions

Study Guide - Flashcards