Question 1

Which of the following statements best explains why antibiotics that poison bacterial ribosomes do not affect ribosomes of archaea or eukaryotes?

Accepted Answer

The molecular composition of ribosomes in archaea and eukaryotes differs from that of bacteria, making them resistant to these antibiotics.

Question 2

A scientist discovers a microbe living in water that is 10 times saltier than seawater. Which group is this organism most likely to belong to?

Accepted Answer

Archaea

Question 3

Which of the following is NOT one of Koch’s postulates for establishing a causative link between a microbe and a disease?

Accepted Answer

The microbe must be able to survive extreme environmental conditions.

Question 4

Which process allows bacteria to acquire new genetic traits by direct cell-to-cell contact?

Accepted Answer

Conjugation

Question 5

A bacterial cell is exposed to environmental stress and forms a tough, dormant structure containing DNA, RNA, ribosomes, and enzymes. What is this structure called?

Accepted Answer

Endospore

Question 6

Which of the following best describes the metabolic strategy of a phototroph?

Accepted Answer

Uses light to excite electrons and produce ATP via photophosphorylation.

Question 7

Why was the oxygen revolution significant for the evolution of life on Earth?

Accepted Answer

It enabled aerobic respiration, which releases more energy due to oxygen’s high electronegativity as the final electron acceptor.

Question 8

Which equation best represents the process of nitrogen fixation carried out by certain bacteria and archaea?

Accepted Answer

$$\mathrm{N_2$ + 3H_2 \rightarrow 2NH_3}$$

Question 9

A farmer uses ammonia ($$\mathrm{NH_3$}) $$fertilizer, which leads to nitrate pollution in a nearby lake. What is the most likely ecological consequence?

Accepted Answer

Development of anaerobic 'dead zones' due to decreased oxygen content.

Question 10

Which of the following is a distinguishing feature of Gram-positive bacteria?

Accepted Answer

Cell wall with extensive peptidoglycan.

Question 11

Which method is used to rapidly identify and characterize previously unknown prokaryotic species by comparing DNA sequences?

Accepted Answer

Metagenomics

Question 12

Which bacterial lineage is filamentous, forms branching chains, and is important in soil decomposition and antibiotic production?

Accepted Answer

Actinobacteria

Question 13

Which of the following best describes lateral gene transfer in prokaryotes?

Accepted Answer

Acquisition of genetic material from another organism, allowing for new traits not available through binary fission.

Question 14

A patient is infected with a strain of Escherichia coli that produces a protein toxin. What genetic feature is most likely responsible for its pathogenicity?

Accepted Answer

Acquisition of virulence genes.

Question 15

Which of the following is a commercial application of extremophiles?

Accepted Answer

Production of enzymes that function at extreme temperatures and pressures for industrial processes.

Question 16

Which metabolic pathway releases the most energy per mole of glucose when oxygen is the final electron acceptor?

Accepted Answer

Aerobic respiration using oxygen as the final electron acceptor.

Question 17

Which group of bacteria is least diverse, consisting of only 13 known species, and lives as parasitic endosymbionts inside host cells?

Accepted Answer

Chlamydiae

Question 18

Which lineage of archaea is most likely to be found in hot, acidic environments such as Yellowstone National Park?

Accepted Answer

Crenarchaeota

Question 19

Which of the following best describes the ecological role of cyanobacteria in aquatic environments?

Accepted Answer

They produce much of the oxygen, nitrogen, and organic compounds that feed organisms in surface waters.

Question 20

Which strategy is NOT used in bioremediation to clean up polluted sites?

Accepted Answer

Removing all bacteria and archaea from the site.

Bacteria and Archaea: Diversity, Structure, and Function

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