Question 1

The pink coloration of the waters in Laguna Salada de Torrevieja is primarily due to which of the following adaptations of prokaryotes?

Accepted Answer

The presence of photosynthetic pigments in extremophilic archaea such as Halobacterium.

Question 2

Which of the following best explains why prokaryotes can reach huge population sizes and adapt rapidly to new environments?

Accepted Answer

They reproduce rapidly by binary fission, accumulate mutations quickly, and exchange genes through horizontal gene transfer.

Question 3

Which structure is responsible for the resistance of some bacteria to extreme environmental conditions, such as heat and desiccation?

Accepted Answer

Endospore

Question 4

A bacterium is observed to have a thick peptidoglycan layer and retains the crystal violet dye during Gram staining. Which of the following is true about this bacterium?

Accepted Answer

It is Gram-positive and is more susceptible to antibiotics targeting peptidoglycan synthesis.

Question 5

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

Accepted Answer

A donor cell transfers DNA to a recipient cell through a pilus, often involving the F factor.

Question 6

Which metabolic strategy is used by cyanobacteria, and what is its ecological significance?

Accepted Answer

Photoautotrophy; they produce oxygen and organic compounds that support aquatic food webs.

Question 7

A patient is infected with a bacterium that is resistant to multiple antibiotics. Which genetic element is most likely responsible for this resistance, and how can it spread to other bacteria?

Accepted Answer

R plasmid; it can be transferred by conjugation using pili.

Question 8

Which of the following equations correctly represents the process of nitrogen fixation carried out by some prokaryotes?

Accepted Answer

$$\mathrm{N_2$ + 8H^+ + 8e^- + 16ATP \rightarrow 2NH_3 + H_2$ + 16ADP + 16P_i}$$

Question 9

Which of the following statements about biofilms is correct?

Accepted Answer

Biofilms are surface-coating colonies where cells cooperate, often causing chronic infections and industrial problems.

Question 10

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

Accepted Answer

They possess an outer membrane containing lipopolysaccharides that restrict antibiotic entry.

Question 11

Which of the following is a real-world example of horizontal gene transfer contributing to human disease?

Accepted Answer

Pathogenic strains of E. coli acquiring toxin genes via transduction.

Question 12

Which of the following best describes the nutritional mode of a bacterium that uses light for energy and organic compounds as a carbon source?

Accepted Answer

Photoheterotroph

Question 13

A scientist discovers a prokaryote living in a hot spring at 90°C. Which group is this organism most likely to belong to, and what is a key adaptation?

Accepted Answer

Archaea; proteins and membranes adapted to high temperatures

Question 14

Which of the following is NOT a function of the bacterial capsule?

Accepted Answer

Carrying out nitrogen fixation

Question 15

Which of the following statements about the CRISPR-Cas9 system is correct?

Accepted Answer

It is a prokaryotic defense mechanism against viruses that has been adapted for gene editing in research.

Question 16

Which of the following best describes the ecological role of chemoheterotrophic prokaryotes?

Accepted Answer

They function as decomposers, recycling nutrients by breaking down dead organisms and waste products.

Question 17

Which of the following is a correct pairing of a prokaryotic group and a disease it causes?

Accepted Answer

Spirochetes; Lyme disease

Question 18

Which of the following statements about the evolutionary origins of bacterial flagella is supported by current evidence?

Accepted Answer

Bacterial flagella evolved through the stepwise modification of simpler ancestral structures.

Question 19

Which of the following best explains why salt is used as a preservative for food?

Accepted Answer

Salt creates a hypertonic environment, causing prokaryotic cells to lose water and undergo plasmolysis, which inhibits their reproduction.

Bacteria and Archaea: Structure, Diversity, and Roles in the Biosphere

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