Question 1

Which of the following best describes the main conclusion of Pasteur’s swan-neck flask experiment regarding spontaneous generation?

Accepted Answer

Microorganisms are present in the air and can contaminate sterile solutions, but do not arise spontaneously.

Question 2

A patient presents with a severe infection caused by a Gram-negative bacterium. Which component of the bacterial cell wall is most likely responsible for triggering a strong immune response and possible septic shock?

Accepted Answer

Lipid A

Question 3

Which of the following statements about Koch’s postulates is correct?

Accepted Answer

They require that the suspected pathogen be isolated and grown in pure culture.

Question 4

Which of the following best explains why oil immersion is used with the 100x objective lens in bright-field microscopy?

Accepted Answer

Oil reduces light refraction between the specimen and the lens, increasing resolution.

Question 5

A microbiologist is using a dichotomous key to identify a bacterial isolate. What is the primary function of a dichotomous key in this context?

Accepted Answer

To sequentially narrow down the identity of the organism through paired, contrasting statements.

Question 6

Which of the following best describes the difference between +ssRNA and –ssRNA viral genomes?

Accepted Answer

+ssRNA can be directly translated by host ribosomes, while –ssRNA must first be transcribed to +ssRNA.

Question 7

Which of the following is a correct example of binomial nomenclature for a bacterial species?

Accepted Answer

Escherichia coli

Question 8

A bacterial cell divides in two perpendicular planes and forms a cubical packet of eight cells. What is the correct term for this arrangement?

Accepted Answer

Sarcina

Question 9

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They enable bacteria to survive harsh environmental conditions.

Question 10

A patient is diagnosed with a prion disease. Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause normal PrP to misfold.

Question 11

Which of the following microscopes would be best for viewing the surface details of a virus particle at the highest possible resolution?

Accepted Answer

Scanning electron microscope

Question 12

Which of the following is a characteristic shared by both prokaryotic and eukaryotic cells?

Accepted Answer

Presence of ribosomes

Question 13

A Gram stain is performed on a bacterial sample. After the procedure, the cells appear pink under the microscope. What does this indicate about the bacterial cell wall?

Accepted Answer

The bacteria have a thin peptidoglycan layer and an outer membrane.

Question 14

Which of the following best describes the function of the glycocalyx in bacteria?

Accepted Answer

It helps bacteria adhere to surfaces and evade the immune system.

Question 15

A scientist is studying a microbe that is 0.5 micrometers in diameter. Which of the following is most likely true about this organism?

Accepted Answer

It is a prokaryote, since most bacteria are measured in micrometers.

Question 16

Which of the following best explains the endosymbiotic theory?

Accepted Answer

Eukaryotic cells evolved from prokaryotic cells by engulfing smaller prokaryotes that became organelles.

Question 17

Which of the following is a correct sequence of taxonomic ranks from most inclusive to least inclusive?

Accepted Answer

Domain, Phylum, Class, Order, Family, Genus, Species

Question 18

A patient is infected with a protozoan pathogen. Which of the following is a general characteristic of protozoa?

Accepted Answer

They are eukaryotic and usually motile.

Question 19

Which of the following best describes the lytic cycle of a bacteriophage?

Accepted Answer

The phage causes immediate lysis of the host cell after replication.

Question 20

Which of the following is a function of Bergey’s Manual of Systematic Bacteriology?

Accepted Answer

It is a reference for the identification and classification of bacteria based on phenotypic and genotypic characteristics.

Microbiology Exam 1 Review: History, Cell Structure, Microscopy, Classification, and Infectious Agents

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