Question 1

Which of the following best explains why binary fission in cocci can result in different arrangements such as chains, tetrads, or clusters?

Accepted Answer

The planes in which the cells divide and whether the daughter cells remain attached after division.

Question 2

A patient presents with a severe cough that has lasted for over 100 days. Laboratory analysis identifies a Gram-negative coccobacillus that paralyzes cilia in the respiratory tract. Which organism is most likely responsible?

Accepted Answer

Bordetella pertussis

Question 3

Which of the following statements about endosymbiotic theory is correct?

Accepted Answer

It explains why mitochondria and prokaryotes both have 70S ribosomes.

Question 4

Which of the following is a distinguishing feature of Mycoplasma species?

Accepted Answer

They lack cell walls and are the smallest free-living cells.

Question 5

A researcher isolates a microorganism from a hot spring with a temperature of 90°C. The organism lacks peptidoglycan, has ether-linked membrane lipids, and produces methane. To which group does this organism most likely belong?

Accepted Answer

Euryarchaeota (methanogenic archaea)

Question 6

Which of the following best describes the function of contractile vacuoles in protozoa?

Accepted Answer

They pump excess water out of the cell to prevent osmotic lysis.

Question 7

Which of the following protozoan groups is characterized by the presence of two nuclei and multiple flagella, and includes a species that causes gastrointestinal infections from contaminated water?

Accepted Answer

Diplomonadida (e.g., Giardia)

Question 8

Which of the following is a correct pairing of a fungal division and its characteristic sexual spore?

Accepted Answer

Zygomycota – zygospore

Question 9

A patient with a history of eating undercooked meat and cleaning cat litter boxes develops neurological symptoms. Which protozoan is most likely responsible, and what is its mode of transmission?

Accepted Answer

Toxoplasma gondii; ingestion of cysts from undercooked meat or cat feces

Question 10

Which of the following best explains why there are more effective treatments for bacterial infections than for viral infections?

Accepted Answer

Bacterial cells are prokaryotic and have unique structures not found in human cells, reducing toxicity of antibiotics.

Question 11

Which of the following is a correct description of the lytic replication cycle of a bacteriophage?

Accepted Answer

The phage attaches, injects its DNA, synthesizes new virions, assembles them, and lyses the host cell to release progeny.

Question 12

Which of the following is a distinguishing feature of the fungal group Basidiomycota?

Accepted Answer

They produce basidiospores on club-shaped structures called basidia.

Question 13

A Gram-negative rod is isolated from a patient with severe diarrhea after drinking contaminated water. The organism is oxidase positive and has a single polar flagellum. Which genus is most likely responsible?

Accepted Answer

Vibrio

Question 14

Which of the following best describes the process of schizogony in protozoa?

Accepted Answer

A single cell undergoes multiple mitoses before cytokinesis, producing many daughter cells called merozoites.

Question 15

Which of the following is a correct statement about prions?

Accepted Answer

They are infectious proteins that cause normal cellular proteins to misfold into a disease-causing form.

Question 16

Which of the following is a key difference between exotoxins and endotoxins?

Accepted Answer

Exotoxins are proteins secreted mainly by Gram-positive bacteria, while endotoxins are lipid A components of the outer membrane of Gram-negative bacteria.

Question 17

A hospital patient develops a secondary infection after prolonged antibiotic therapy, which reduces the normal microbiota and allows a different pathogen to thrive. What is this type of infection called?

Accepted Answer

Superinfection

Question 18

Which of the following best describes the role of arthropod vectors in disease transmission?

Accepted Answer

They can be biological vectors, in which the pathogen completes part of its life cycle inside the vector.

Question 19

Which of the following is a correct definition of prevalence in epidemiology?

Accepted Answer

The total number of cases, both new and existing, in a given area during a given period.

Microbiology Study Guide: Prokaryotes, Eukaryotes, and Viruses

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