Question 1

Which of the following statements best explains why prokaryotes are considered the most diverse domain of life on Earth?

Accepted Answer

Prokaryotes include both Bacteria and Archaea, which together outnumber eukaryotic species and occupy a wider range of environments.

Question 2

Which feature distinguishes Bacteria from Archaea at the cellular level?

Accepted Answer

Bacteria have cell walls containing peptidoglycan, while Archaea do not.

Question 3

Gram staining is a laboratory technique used to classify bacteria. What does a positive Gram stain indicate about a bacterial cell wall?

Accepted Answer

It contains a thick layer of peptidoglycan.

Question 4

The first cells on Earth are thought to have used $ \mathrm{H_2S} $ as an electron donor for photosynthesis. What was a likely byproduct of this process?

Accepted Answer

$ \mathrm{S} $ (elemental sulfur)

Question 5

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

Accepted Answer

They provide fossil evidence of some of the earliest prokaryotic life on Earth.

Question 6

A scientist is studying a microorganism that thrives in extremely hot, acidic environments and lacks peptidoglycan in its cell wall. To which domain does this organism most likely belong?

Accepted Answer

Archaea

Question 7

Which of the following is a real-world application of prokaryotes in environmental management?

Accepted Answer

Using bacteria to decompose organic waste in sewage treatment plants.

Question 8

Nitrogen-fixing bacteria are essential for life on Earth because they:

Accepted Answer

Convert atmospheric $ \mathrm{N_2} $ into ammonia ($ \mathrm{NH_3} $), making nitrogen available to plants.

Question 9

Which of the following best explains why prokaryotes are considered the ancestors of all life forms?

Accepted Answer

The universal ancestor of all life was prokaryotic, as shown by the three-domain tree of life.

Question 10

A researcher isolates a microorganism with the following characteristics: no nucleus, presence of peptidoglycan in the cell wall, and the ability to form endospores. Which group does this organism most likely belong to?

Accepted Answer

Bacteria

Question 11

Which of the following is NOT a method commonly used to study prokaryotes?

Accepted Answer

Observing mitosis under a microscope.

Question 12

If a prokaryote is classified as a spirochaete, which of the following is most likely true about its morphology?

Accepted Answer

It has a unique spiral-shaped cell form.

Question 13

Which of the following equations best represents the process of oxygenic photosynthesis that evolved in prokaryotes?

Accepted Answer

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

Question 14

Which of the following statements about the three domains of life is correct?

Accepted Answer

Both Bacteria and Archaea are prokaryotic, while Eukarya are eukaryotic.

Question 15

A medical laboratory receives a sample suspected of containing pathogenic bacteria. Which of the following steps would be most useful for initial identification?

Accepted Answer

Performing a Gram stain to determine cell wall structure.

Question 16

Which of the following best explains why Archaea can survive in extreme environments such as hot springs and salt lakes?

Accepted Answer

Their unique membrane lipids and enzymes are adapted to withstand extreme conditions.

Question 17

Which of the following is a correct statement about the role of prokaryotes in the carbon cycle?

Accepted Answer

Prokaryotes decompose organic matter, releasing $ \mathrm{CO_2} $ back into the atmosphere.

Question 18

Which of the following best describes the relationship between prokaryotes and eukaryotes in the evolutionary tree of life?

Accepted Answer

Eukaryotes share a more recent common ancestor with Archaea than with Bacteria.

Question 19

A biologist discovers a new microorganism that is rod-shaped, lacks a nucleus, and is able to fix nitrogen. Which of the following is most likely true about this organism?

Accepted Answer

It is a prokaryote, possibly a member of the Bacteria domain.

Bacteria and Archaea: Diversity, Evolution, and Study Methods

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