Question 1

Which of the following best describes the process of binary fission in prokaryotes?

Accepted Answer

A process where one cell divides into two genetically identical daughter cells, involving septum formation and partitioning of cellular components.

Question 2

A bacterium is found to grow optimally at 4°C and is isolated from Antarctic ice. Which category does this organism most likely belong to?

Accepted Answer

Psychrophile

Question 3

Which adaptation would you expect to find in the cytoplasmic membrane of a psychrophilic bacterium?

Accepted Answer

High content of unsaturated and short-chain fatty acids

Question 4

Which of the following equations correctly represents the formation of hydrogen peroxide as a toxic byproduct of oxygen metabolism?

Accepted Answer

$$\mathrm{O_2$^- + e^- + 2H^+ \rightarrow H_2O_2}$$

Question 5

A bacterium isolated from a soda lake grows optimally at pH 10. Which adaptation is most likely present in this organism?

Accepted Answer

It uses sodium ion exchange to maintain internal pH near neutrality.

Question 6

Which of the following is a major function of iron (Fe) in microbial cells?

Accepted Answer

Cofactor in cellular respiration and oxidation-reduction reactions

Question 7

Which of the following best explains why obligate anaerobes cannot survive in the presence of oxygen?

Accepted Answer

They lack the enzymes necessary to detoxify reactive oxygen species such as superoxide and hydrogen peroxide.

Question 8

Which of the following is a compatible solute commonly accumulated by halophilic bacteria to maintain osmotic balance?

Accepted Answer

Glycine betaine

Question 9

A bacterium that can grow in the presence or absence of oxygen, but grows better with oxygen, is classified as:

Accepted Answer

Facultative anaerobe

Question 10

Which of the following best describes the role of biofilms in microbial survival?

Accepted Answer

Biofilms provide a protective matrix that resists immune responses and antimicrobials, and facilitate nutrient and waste exchange.

Question 11

Which of the following is a correct description of a chemolithoautotroph?

Accepted Answer

Uses inorganic chemicals as an energy source and $$\mathrm{CO_2$} as a $$carbon source.

Question 12

Which of the following is a likely consequence for a bacterium placed in an environment with very low water activity ($$a_w$$)?

Accepted Answer

The cytoplasmic membrane will shrink from the cell wall (plasmolysis) due to water loss.

Question 13

Which of the following is NOT a macronutrient required in large amounts by bacterial cells?

Accepted Answer

Iron (Fe)

Question 14

Which of the following best explains why enzymes from hyperthermophiles are useful in industrial applications such as PCR?

Accepted Answer

They are stable and function optimally at high temperatures due to increased ionic bonding and hydrophobic interiors.

Question 15

A bacterium that grows best in the presence of high sugar concentrations is classified as:

Accepted Answer

Osmophile

Question 16

Which of the following is a primary reason why carbon is essential for microbial growth?

Accepted Answer

It forms the backbone of all major macromolecules such as proteins, lipids, polysaccharides, and nucleic acids.

Question 17

Which of the following best describes the function of the septum during bacterial cell division?

Accepted Answer

It is a partition that forms between dividing cells, leading to cell separation.

Question 18

Which of the following is a correct equation for the detoxification of hydrogen peroxide by catalase?

Accepted Answer

$$\mathrm{2H_2O_2 \rightarrow 2H_2O + O_2$}$$

Question 19

Which of the following is a real-world consequence of biofilm formation in medical settings?

Accepted Answer

Biofilms can cause persistent infections on implanted medical devices due to their resistance to antimicrobials.

Microbial Metabolism and Growth: Environmental and Nutritional Factors

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