Question 1

Which scientist is credited with disproving the theory of spontaneous generation through his swan-neck flask experiment?

Accepted Answer

Louis Pasteur

Question 2

During the Gram stain procedure, why do Gram-positive bacteria retain the crystal violet stain and appear purple?

Accepted Answer

They have a thick peptidoglycan layer that retains the crystal violet-iodine complex.

Question 3

Which of the following is NOT a characteristic of prokaryotic cells?

Accepted Answer

Presence of membrane-bound organelles

Question 4

Which process describes the movement of molecules from an area of high concentration to an area of low concentration without the use of energy?

Accepted Answer

Passive transport

Question 5

According to the endosymbiotic theory, which organelle is believed to have originated from a free-living prokaryote?

Accepted Answer

Mitochondrion

Question 6

Which of the following best describes a halophile?

Accepted Answer

An organism that thrives in high salt concentrations

Question 7

A bacterial culture is grown in a medium containing only $$\mathrm{N_2$} as $$the nitrogen source. Which process must the bacteria be capable of to grow?

Accepted Answer

Nitrogen fixation ($$\mathrm{N_2$ \rightarrow NH_3$})$$

Question 8

Which of the following is a correct pairing of bacterial morphology and description?

Accepted Answer

Spirillum: spiral-shaped

Question 9

Which type of bacteria is responsible for producing endospores?

Accepted Answer

Gram-positive bacteria

Question 10

A microbiologist wants to isolate a single type of bacterium from a mixed culture. Which method should they use to obtain a pure culture?

Accepted Answer

Streak plate method

Question 11

Which of the following best describes an obligate aerobe?

Accepted Answer

An organism that requires oxygen for growth

Question 12

Which phase of the bacterial growth curve is characterized by rapid cell division and exponential increase in cell number?

Accepted Answer

Log (exponential) phase

Question 13

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms provide protection to bacteria from environmental stress.

Question 14

Which of the following is a distinguishing feature of archaea compared to bacteria and eukaryotes?

Accepted Answer

Ability to survive in extreme environments such as high salinity or temperature

Question 15

Which of the following best describes the function of the bacterial cell wall?

Accepted Answer

It provides structural support and protects against osmotic lysis.

Question 16

A bacterium is classified as a chemoautotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

Inorganic chemicals for energy, CO$$_2$$ for carbon

Question 17

Which of the following is a correct sequence of events in binary fission?

Accepted Answer

DNA replication → cell elongation → septum formation → cell separation

Question 18

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 that restricts entry of many antibiotics.

Question 19

A microbiologist is studying a bacterium that can grow in the presence or absence of oxygen, but grows better with oxygen. What is the correct classification for this organism?

Accepted Answer

Facultative anaerobe

Question 20

Which of the following best describes the role of cell walls in osmotic balance?

Accepted Answer

Cell walls prevent the cell from bursting in hypotonic environments.

Microbiology Test 1 Review: Foundational Concepts and Processes

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