Question 1

Which of the following statements best explains why Archaea are considered more closely related to Eukaryotes than to Bacteria?

Accepted Answer

Archaea and Eukaryotes both have 80s ribosomes and DNA associated with histone proteins.

Question 2

A scientist discovers a prokaryote living in a hot spring at 100°C and pH 1.0. Which term best describes this organism, and why is it of interest to researchers?

Accepted Answer

It is an extremophile, and its enzymes may be useful for biotechnology applications such as PCR.

Question 3

Which of the following is NOT one of Koch’s postulates for linking a specific microbe to a specific disease?

Accepted Answer

The microbe must be genetically engineered to lose its virulence.

Question 4

Gram-positive and Gram-negative bacteria differ in their cell wall structure. Which of the following correctly describes this difference?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and stain bluish purple with Gram stain.

Question 5

Which of the following best describes the process of nitrogen fixation?

Accepted Answer

Conversion of nitrogen gas ($$N_2) to $$ammonia ($$NH_3) by $$certain prokaryotes using the enzyme nitrogenase.

Question 6

A patient is infected with a bacterial strain of $$E. coli$$ that produces a toxin inhibiting 80s ribosomes. What is the most direct effect of this toxin on the patient’s cells?

Accepted Answer

It blocks protein synthesis in the patient’s cells.

Question 7

Which of the following best explains why antibiotic resistance has become a major challenge in modern medicine?

Accepted Answer

Widespread and extensive use of antibiotics has selected for bacteria with resistance genes.

Question 8

Which of the following is a correct pairing of metabolic strategy and energy source in prokaryotes?

Accepted Answer

Chemolithotroph – inorganic molecules such as methane ($$CH_4)$$

Question 9

Which of the following statements about the human microbiome is TRUE?

Accepted Answer

Gut prokaryotes can aid in digestion, synthesize vitamins, and even impact mood.

Question 10

A researcher is studying a prokaryote that uses $$CO_2 as a $$carbon source and $$H_2S as an $$electron donor for photosynthesis. Which terms best describe this organism?

Accepted Answer

Phototroph and autotroph

Question 11

Which of the following is a reason why prokaryotes are used in bioremediation?

Accepted Answer

They can degrade hydrophobic organic pollutants that accumulate in sediments.

Question 12

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

Accepted Answer

They were the first organisms to perform oxygenic photosynthesis, leading to the accumulation of $$O_2 in $$Earth’s atmosphere.

Question 13

Which of the following is NOT a method by which prokaryotes introduce genetic variation into their populations?

Accepted Answer

Binary fission

Question 14

A chain of spherical bacteria is observed under a microscope. What is the correct term for this arrangement?

Accepted Answer

Streptococcus

Question 15

Which of the following best explains why an autoclave is required to sterilize materials contaminated with endospore-forming bacteria?

Accepted Answer

Endospores are resistant to high temperature, radiation, and antibiotics, requiring both high heat and pressure to be destroyed.

Question 16

Which of the following scenarios best illustrates the ecological impact of nitrogen pollution from fertilizers?

Accepted Answer

Nitrates leach into waterways, causing algal blooms that result in anoxic 'dead zones' when the algae die and decompose.

Question 17

Which of the following statements about prokaryotic metabolic diversity is TRUE?

Accepted Answer

Prokaryotes can use a greater variety of electron donors and acceptors in cellular respiration than eukaryotes.

Question 18

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

Accepted Answer

It fixes atmospheric nitrogen ($$N_2) $$into ammonia ($$NH_3) in $$root nodules of legumes.

Question 19

Which of the following methods allows scientists to study prokaryotes that cannot be cultured in the laboratory?

Accepted Answer

Metagenomics, which analyzes DNA sequences from environmental samples.

Question 20

Which of the following is a correct statement about the plasma membrane phospholipids of Bacteria and Archaea?

Accepted Answer

Bacteria have phospholipids with fatty acid tails, like eukaryotes, while Archaea have phospholipids with isoprene chains.

Bacteria and Archaea: Structure, Diversity, and Ecological Roles

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