Question 1

Which of the following best describes a chemotroph?

Accepted Answer

An organism that obtains energy from organic or inorganic chemicals.

Question 2

A bacterium that uses organic molecules as its electron donor is classified as:

Accepted Answer

Organotroph

Question 3

Which equation correctly represents a redox reaction?

Accepted Answer

$$\mathrm{A} + \mathrm{B} \rightarrow \mathrm{A}^+ + \mathrm{B}^-$$

Question 4

Obligate anaerobes are susceptible to oxygen because:

Accepted Answer

They lack enzymes to detoxify reactive oxygen species.

Question 5

Carotenoids protect cells from singlet oxygen by:

Accepted Answer

Quenching singlet oxygen and preventing oxidative damage.

Question 6

Which of the following vitamins acts as an antioxidant in humans?

Accepted Answer

Vitamin C

Question 7

A facultative anaerobe is best described as:

Accepted Answer

An organism that can use oxygen when it is available but can also grow without it.

Question 8

Nitrogen fixation is carried out by certain bacteria. Which equation best represents this process?

Accepted Answer

$$\mathrm{N}_2 + 3\mathrm{H}_2 \rightarrow 2\mathrm{NH}_3$$

Question 9

Which organic compound requires phosphorus for its structure?

Accepted Answer

Nucleic acids

Question 10

Which of the following is a trace element required by humans?

Accepted Answer

Iron

Question 11

What effect does high temperature have on enzyme structure?

Accepted Answer

It denatures the enzyme, disrupting its three-dimensional structure.

Question 12

Which of the following best describes a psychrotolerant organism?

Accepted Answer

It can grow at low temperatures but prefers moderate temperatures.

Question 13

Which organism is classified as a thermoduric pathogen relevant to humans?

Accepted Answer

Bacillus cereus

Question 14

Helicobacter pylori is best described as:

Accepted Answer

An acid-tolerant microbe

Question 15

Staphylococcus aureus is an example of:

Accepted Answer

Facultative halophile

Question 16

Which equation best represents logarithmic growth during binary fission?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 17

Which phase of microbial population growth is characterized by rapid cell division?

Accepted Answer

Log phase

Question 18

What is the primary function of a chemostat in microbiology?

Accepted Answer

To maintain a microbial culture in continuous exponential growth.

Question 19

Which bacteria are most associated with dental plaque and caries?

Accepted Answer

Streptococcus mutans

Question 20

Which of the following best describes a defined medium?

Accepted Answer

A medium with precisely known chemical composition.

Microbiology Chapter 6 Study Guide – Step-by-Step Guidance

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