Question 1

Which of the following best describes microbial growth?

Accepted Answer

An increase in the population of microbes resulting in a discrete colony

Question 2

Which nutrient is most likely to limit microbial growth if it is insufficient?

Accepted Answer

Nitrogen

Question 3

A bacterium that can use light as an energy source and carbon dioxide as a carbon source is classified as a:

Accepted Answer

Photoautotroph

Question 4

Which type of microorganism would you expect to find growing at the bottom of a test tube where oxygen concentration is lowest?

Accepted Answer

Obligate anaerobes

Question 5

Which enzyme is responsible for neutralizing superoxide radicals in aerobic bacteria?

Accepted Answer

Superoxide dismutase

Question 6

What is the chemical reaction catalyzed by catalase?

Accepted Answer

$$2H_2O_2 \rightarrow 2H_2O + O_2$

Question 7

Which physical factor can cause denaturation of microbial proteins?

Accepted Answer

High temperature

Question 8

A microorganism that grows best at pH 2 is classified as a(n):

Accepted Answer

Acidophile

Question 9

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms form as a result of quorum sensing

Question 10

Which isolation technique is most commonly used to obtain pure cultures from a mixed sample?

Accepted Answer

Streak plate

Question 11

Which type of culture medium would you use to differentiate bacteria based on their ability to ferment lactose?

Accepted Answer

Differential medium

Question 12

A halophile is an organism that:

Accepted Answer

Lives in high salt concentrations

Question 13

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 14

What is the generation time in bacterial growth?

Accepted Answer

The time required for a bacterial cell to grow and divide

Question 15

Which method is an indirect way to estimate microbial population size?

Accepted Answer

Turbidity measurement

Question 16

Why are obligate anaerobes unable to survive in the presence of oxygen?

Accepted Answer

They lack enzymes to neutralize toxic oxygen species

Question 17

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

Accepted Answer

A bioreactor where fresh medium is continuously added and culture liquid is removed to keep volume constant

Question 18

Which of the following equations represents the reaction catalyzed by superoxide dismutase?

Accepted Answer

$$2O_2^- + 2H^+ \rightarrow O_2$ + H_2O_2$$

Question 19

Which type of microorganism would you expect to find in hot springs with temperatures above 80°C?

Accepted Answer

Hyperthermophiles

Question 20

Which preservation method would be most suitable for storing microbial cultures for decades?

Accepted Answer

Lyophilization (freeze-drying)

Microbial Nutrition and Growth: Study Notes

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