Question 1

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

Accepted Answer

Gram-negative bacteria possess an outer membrane composed of lipids bonded to carbohydrates, which acts as a barrier to many antibiotics.

Question 2

A patient develops a severe infection after a pacemaker is implanted. The infection is difficult to treat, even with strong antibiotics. Which property of prokaryotes most likely explains this phenomenon?

Accepted Answer

The bacteria form biofilms on the pacemaker, which protect them from antibiotics and immune responses.

Question 3

Which of the following best describes the difference between exotoxins and endotoxins?

Accepted Answer

Exotoxins are secreted proteins, while endotoxins are lipid components of Gram-negative bacterial membranes released upon cell death.

Question 4

Which structure allows bacteria such as Streptococcus to adhere to human tissues, such as the tonsils, and evade the immune system?

Accepted Answer

Capsule

Question 5

A scientist isolates a prokaryote from a hot spring with a temperature of $$80^\circC $$and a pH of 2. Which group does this organism most likely belong to?

Accepted Answer

Thermophiles

Question 6

Which of the following best describes the nutritional mode of Nitrosomonas communis, a chemoautotrophic proteobacterium?

Accepted Answer

It uses inorganic chemicals for energy and carbon dioxide as a carbon source.

Question 7

Which of the following scenarios best illustrates endosymbiosis?

Accepted Answer

A bacterium living inside the root cells of a plant, providing nitrogen in exchange for carbohydrates.

Question 8

A patient with a disrupted gut microbiota due to antibiotic use experiences persistent hunger and weight gain. Which hormone and bacterial species are most directly involved in this scenario?

Accepted Answer

Ghrelin and Helicobacter pylori

Question 9

Which of the following is NOT a characteristic of all eukaryotic algal protists?

Accepted Answer

They all possess cilia and flagella for movement.

Question 10

Which of the following best describes the life cycle of multicellular algae?

Accepted Answer

Gametophytes are haploid ($$n) $$and upon fusion form a diploid ($$2n) $$sporophyte.

Question 11

Which of the following is a mixotrophic protist capable of both photosynthesis and ingesting other organisms?

Accepted Answer

Euglena

Question 12

A bacterial cell is observed to survive boiling temperatures and later resume growth when conditions improve. Which structure is responsible for this survival?

Accepted Answer

Endospore

Question 13

Which of the following statements about biofilms is FALSE?

Accepted Answer

Biofilms are easily penetrated and destroyed by most antibiotics.

Question 14

Which of the following pairs is correctly matched with its nutritional mode?

Accepted Answer

Rhodopseudomonas palustris – Photoheterotroph

Question 15

Which group of protists is characterized by living in anaerobic environments and having modified mitochondria lacking an electron transport chain?

Accepted Answer

Excavata

Question 16

Which of the following best explains why antibiotics like penicillin are often ineffective against bacteria in biofilms?

Accepted Answer

Biofilms produce enzymes that can break down antibiotics and prevent their penetration beyond the outer layers.

Question 17

Which of the following is a correct statement about the evolutionary origin of Archaeplastida?

Accepted Answer

Archaeplastida evolved from endosymbiosis of cyanobacteria, which are prokaryotic autotrophs.

Question 18

Which of the following best describes the function of fimbriae in prokaryotes?

Accepted Answer

Attachment to surfaces and host cells

Question 19

Which of the following is a real-world example of symbiosis involving proteobacteria?

Accepted Answer

Rhizobium bacteria living in root nodules of legumes, fixing nitrogen for the plant

Prokaryotes and Protists: Structure, Diversity, and Function

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