Question 1

Which of the following is NOT considered evidence supporting the endosymbiotic theory for the origin of mitochondria and chloroplasts?

Accepted Answer

Both organelles are surrounded by a peptidoglycan cell wall.

Question 2

A bacterial culture is inoculated into fresh medium. After a short period, the bacteria begin to divide rapidly. Which phase of the bacterial growth curve does this describe, and what is the primary cellular activity during this phase?

Accepted Answer

Log (exponential) phase; cells are dividing at a constant and maximum rate.

Question 3

Secondary metabolites in bacteria are typically produced during which phase of the growth curve, and what is their primary function?

Accepted Answer

Stationary phase; to provide competitive advantages such as antibiotics.

Question 4

A bacterium that grows optimally at $$15^\circ C$$ but not above $$20^\circ C is $$best classified as a:

Accepted Answer

Psychrophile

Question 5

Which type of medium would you use to distinguish between bacteria that can ferment lactose and those that cannot, and what is a classic example of such a medium?

Accepted Answer

Differential medium; MacConkey agar

Question 6

On blood agar, a bacterial colony surrounded by a clear, colorless zone is exhibiting which type of hemolysis, and what does this indicate?

Accepted Answer

Beta hemolysis; complete lysis of red blood cells

Question 7

Which of the following best describes a defined (synthetic) medium?

Accepted Answer

A medium in which all chemical components and their concentrations are known

Question 8

Which of the following statements correctly distinguishes between heterotrophs and autotrophs?

Accepted Answer

Heterotrophs use organic carbon sources; autotrophs use carbon dioxide as their carbon source.

Question 9

Which of the following groups is correctly matched with its kingdom?

Accepted Answer

Fungi – Kingdom Fungi

Question 10

A laboratory technician needs to reduce a bacterial culture from $$10^8$$ CFU/mL to $$10^3$$ CFU/mL using serial 1:10 dilutions. How many serial dilutions are required?

Accepted Answer

$$5$$

Question 11

Which of the following best differentiates a disinfectant from an antiseptic?

Accepted Answer

Disinfectants are used on inanimate objects; antiseptics are safe for use on living tissue.

Question 12

What is the definition of sterilization in microbiology?

Accepted Answer

The destruction of all forms of microbial life, including spores.

Question 13

The D-value ($$D) in $$microbial control is defined as:

Accepted Answer

The time required to reduce a microbial population by $$90\% at a $$specific temperature.

Question 14

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of biochemical reactions.

Question 15

The active site of an enzyme is best described as:

Accepted Answer

The site where substrates bind and the reaction occurs.

Question 16

Which of the following is an example of a coenzyme?

Accepted Answer

NAD$$^+$$

Question 17

In the following reaction, which molecule is being oxidized?

$$\mathrm{C_6H_{12}O_6$} + 6\ \mathrm{O_2$} \rightarrow 6\ \mathrm{CO_2$} + 6\ \mathrm{H_2O}$$

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$

Question 18

Which of the following correctly lists the net ATP yield from one molecule of glucose after glycolysis, TCA cycle, and electron transport chain in prokaryotes?

Accepted Answer

$$38$$ ATP

Question 19

During anaerobic fermentation, what is the primary role of pyruvate?

Accepted Answer

To act as the final electron acceptor and regenerate NAD$$^+.$$

Question 20

In prokaryotic cells, where does the electron transport chain occur?

Accepted Answer

In the plasma (cell) membrane

Microbiology Study Guide: Cell Structure, Microbial Growth, Metabolism, and Control

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