Question 1

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

Accepted Answer

Gram-negative bacteria possess an outer membrane that acts as a barrier to many antibiotics.

Question 2

A scientist discovers a unicellular organism living in a hot spring with temperatures above 90°C. The organism lacks peptidoglycan in its cell wall and can survive in highly saline environments. To which domain does this organism most likely belong?

Accepted Answer

Archaea

Question 3

Which of the following best describes the process of bacterial conjugation?

Accepted Answer

Two bacteria temporarily join via a pilus, and DNA is transferred from donor to recipient.

Question 4

Which structure is responsible for the movement of most motile bacteria, and what is the evolutionary significance of this structure?

Accepted Answer

Flagella; they are analogous structures that evolved independently in bacteria, archaea, and eukaryotes.

Question 5

A Gram stain is performed on a bacterial sample. After the procedure, the cells appear pink under the microscope. What can you infer about the cell wall structure of these bacteria?

Accepted Answer

They have a thin peptidoglycan layer and an outer membrane.

Question 6

Which of the following is a correct match between prokaryotic cell shape and its description?

Accepted Answer

Spirillum – spiral

Question 7

Why are endospores significant in the context of bacterial survival and disease transmission?

Accepted Answer

Endospores are highly resistant structures that allow bacteria to survive extreme conditions for long periods.

Question 8

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

Accepted Answer

They are circular DNA molecules that often carry genes for antibiotic resistance.

Question 9

A patient is infected with a bacterium that is an obligate anaerobe. Which of the following treatments would be most effective in controlling the infection?

Accepted Answer

Increasing oxygen supply to the infected tissue

Question 10

Which of the following is an example of metabolic cooperation in prokaryotes?

Accepted Answer

Different cells in a filament of Anabaena specializing in either photosynthesis or nitrogen fixation and exchanging products.

Question 11

Which of the following best explains why prokaryotes can evolve rapidly?

Accepted Answer

They reproduce quickly, allowing mutations to accumulate rapidly in populations.

Question 12

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

Accepted Answer

Rhizobium bacteria fixing nitrogen in the root nodules of legume plants

Question 13

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

Binary fission

Question 14

A researcher is studying a prokaryote that can use light as an energy source and CO$$_2 as a $$carbon source. Which nutritional category does this organism belong to?

Accepted Answer

Photoautotroph

Question 15

Which of the following best describes the function of bacterial fimbriae?

Accepted Answer

They enable bacteria to attach to surfaces or other cells.

Question 16

Which of the following statements about nitrogen fixation is correct?

Accepted Answer

It converts atmospheric nitrogen (N$$_2) $$into ammonia (NH$$_3$$), which can be used to make amino acids.

Question 17

Which of the following is a key difference between the cell walls of Bacteria and Archaea?

Accepted Answer

Bacterial cell walls contain peptidoglycan, while archaeal cell walls lack peptidoglycan.

Question 18

Which of the following best explains why antibiotics such as tetracycline and erythromycin can inhibit bacterial growth without harming human cells?

Accepted Answer

They bind to prokaryotic ribosomes, which differ in structure from eukaryotic ribosomes.

Question 19

A patient is diagnosed with a bacterial infection. The bacteria are found to be resistant to multiple antibiotics. Which genetic element is most likely responsible for this resistance?

Accepted Answer

R plasmids

Question 20

Which of the following ecological roles is performed by chemoheterotrophic prokaryotes?

Accepted Answer

Decomposing dead organisms and recycling nutrients

Study Guide: Bacteria and Archaea (Prokaryotes) – Structure, Function, Diversity, and Impact

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