Question 1

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

Accepted Answer

Bacteria have peptidoglycan in their cell walls, while Archaea do not.

Question 2

A scientist discovers a unicellular organism that is 1.2 µm in diameter, lacks a nucleus, and has a thick peptidoglycan cell wall. Which of the following is most likely true about this organism?

Accepted Answer

It is a bacterium and will stain purple with Gram staining.

Question 3

Which of the following best explains why penicillin is effective against many bacteria but not against human cells?

Accepted Answer

Penicillin inhibits the synthesis of peptidoglycan, which is found in bacterial cell walls but not in human cells.

Question 4

Which metabolic mode is correctly matched with its energy and carbon sources?

Accepted Answer

Photoautotroph: light for energy, $$CO_2$$ for carbon

Question 5

A bacterium that can survive in both the presence and absence of oxygen by switching between aerobic respiration and fermentation is best described as a(n):

Accepted Answer

Facultative anaerobe

Question 6

Which process allows prokaryotes to acquire new genetic material from their environment, such as DNA fragments released by dead cells?

Accepted Answer

Transformation

Question 7

Why is ribosomal RNA (rRNA) commonly used to infer phylogenetic relationships among prokaryotes?

Accepted Answer

rRNA genes are ancient, present in all organisms, and evolve slowly, making them reliable for deep evolutionary comparisons.

Question 8

Which of the following is a real-world example of mutualism involving prokaryotes?

Accepted Answer

Bacteria in the human gut producing vitamins that humans absorb

Question 9

A researcher is studying a prokaryote that oxidizes hydrogen sulfide ($$H_2S) $$for energy and uses $$CO_2 as $$its carbon source. Which nutritional mode does this organism exhibit?

Accepted Answer

Chemoautotrophy

Question 10

Which of the following best describes the role of prokaryotes in the nitrogen cycle?

Accepted Answer

They fix atmospheric $$N_2$$ into ammonia, oxidize ammonia to nitrate, and return $$N_2 to $$the atmosphere through denitrification.

Question 11

Which of the following is a major reason why horizontal gene transfer complicates the construction of prokaryotic phylogenies?

Accepted Answer

Genes acquired horizontally may not reflect the true evolutionary history of the species.

Question 12

Which group of bacteria is responsible for producing oxygen through photosynthesis and is the evolutionary ancestor of chloroplasts in plants?

Accepted Answer

Cyanobacteria

Question 13

A patient is infected with a bacterium that is resistant to penicillin but sensitive to tetracycline. What is the most likely explanation for this resistance?

Accepted Answer

The bacterium has a cell wall that is not affected by penicillin, possibly due to a lack of peptidoglycan or altered peptidoglycan synthesis.

Question 14

Which of the following best describes the function of fimbriae in prokaryotes?

Accepted Answer

Attachment to surfaces or other cells

Question 15

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

Accepted Answer

Multiple linear chromosomes in homologous pairs

Question 16

Which of the following best explains why biofilms are medically significant?

Accepted Answer

Biofilms protect bacteria from antibiotics and immune responses, making infections harder to treat.

Question 17

Which of the following is a correct sequence of steps in the formation of a biofilm?

Accepted Answer

Attachment to surface → secretion of signaling molecules → recruitment of other cells → formation of matrix

Question 18

Which of the following is a unique feature of archaeal cell membranes compared to bacterial cell membranes?

Accepted Answer

Archaeal membranes contain ether-linked lipids, while bacterial membranes contain ester-linked lipids.

Question 19

A prokaryote living in a hot, acidic spring and producing methane as a metabolic byproduct is most likely a(n):

Accepted Answer

Methanogenic archaeon

Prokaryotes: Diversity, Structure, Metabolism, and Importance

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