Question 1

Which of the following statements best describes the relationship among the three domains of life according to Woese (1977)?

Accepted Answer

Eukarya and Archaea share a more recent common ancestor with each other than either does with Bacteria.

Question 2

Which feature is unique to Bacteria and not found in Archaea or Eukarya?

Accepted Answer

Presence of peptidoglycan in the cell wall

Question 3

A scientist discovers a microorganism that thrives in boiling hot springs and produces methane as a metabolic byproduct. To which group does this organism most likely belong?

Accepted Answer

Archaea

Question 4

Which of the following best explains why antibiotics like penicillin are effective against bacteria but not against human cells?

Accepted Answer

Human cells lack peptidoglycan in their cell walls, which is targeted by penicillin.

Question 5

Which process allows bacteria to acquire new genetic material from their environment, potentially increasing genetic diversity?

Accepted Answer

Transformation

Question 6

A patient is infected with a bacterium that is resistant to multiple antibiotics. Which genetic mechanism most likely contributed to this resistance?

Accepted Answer

Acquisition of resistance plasmids through horizontal gene transfer

Question 7

Which of the following equations best represents the exponential growth of a bacterial population under optimal conditions?

Accepted Answer

$N_t = N_0 e^{rt}$

Question 8

Which metabolic strategy is used by organisms that obtain energy from sunlight and carbon from inorganic sources?

Accepted Answer

Photoautotrophy

Question 9

Why are prokaryotes considered essential for nutrient cycling in ecosystems?

Accepted Answer

They convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), making nitrogen available to other organisms.

Question 10

A Gram-negative bacterium is more likely than a Gram-positive bacterium to:

Accepted Answer

Possess an outer membrane containing lipopolysaccharides

Question 11

Which of the following best describes the difference between obligate aerobes and obligate anaerobes?

Accepted Answer

Obligate aerobes require oxygen for survival, while obligate anaerobes are poisoned by oxygen.

Question 12

Which of the following is a real-world example of beneficial bacteria use?

Accepted Answer

Bioremediation of chemical spills

Question 13

Which statement about the evolutionary history of multicellularity is supported by the three-domain system?

Accepted Answer

Multicellularity evolved independently multiple times (polyphyletic origin).

Question 14

Which of the following best explains why bacterial populations can evolve rapidly?

Accepted Answer

They have short generation times and large population sizes, increasing the chance for mutations.

Question 15

A researcher finds a prokaryote with a cell wall but no peptidoglycan, living in a highly saline environment. This organism is most likely:

Accepted Answer

A halophilic archaeon

Question 16

Which of the following is NOT a function of plasmids in bacteria?

Accepted Answer

Carrying essential genes for basic cell survival

Question 17

Which of the following best describes the process of transduction in bacteria?

Accepted Answer

Transfer of genetic material via bacteriophages (viruses)

Question 18

Which of the following is a plausible reason why antibiotics that target prokaryotic ribosomes do not harm eukaryotic cells?

Accepted Answer

Prokaryotic ribosomes have different protein and RNA structures than eukaryotic ribosomes.

Question 19

Which of the following is a correct pairing of a bacterial group and its ecological or medical significance?

Accepted Answer

Cyanobacteria – oxygenic photosynthesis

Question 20

A hospital outbreak of a Gram-negative, endotoxic bacterium is most likely to be caused by which of the following?

Accepted Answer

A member of the Proteobacteria

Bacteria and Archaea: Structure, Diversity, and Roles in Biology

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