Question 1

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

Accepted Answer

A single cell divides into two identical daughter cells after DNA replication and formation of a cross-wall.

Question 2

A bacterial culture starts with 10 cells. If the generation time is 30 minutes, how many cells will there be after 3 hours? Use the formula $$N_f = (N_i)2^n.$$

Accepted Answer

$$N_f = 10 	imes 2^6$ = 640$$

Question 3

Which phase of the bacterial growth curve is characterized by a balance between cell division and cell death?

Accepted Answer

Stationary phase

Question 4

A microbiologist wants to count the number of viable bacteria in a water sample. Which method should they use?

Accepted Answer

Plate count method

Question 5

Which of the following best explains why food with high sugar or salt content is less likely to spoil?

Accepted Answer

High osmotic pressure causes plasmolysis in bacteria, inhibiting their growth.

Question 6

Which enzyme is responsible for removing hydrogen peroxide in aerobic bacteria?

Accepted Answer

Catalase

Question 7

A bacterium that grows best at pH 3 is classified as a:

Accepted Answer

Acidophile

Question 8

Which of the following organisms would you expect to find growing in a hot spring at 90°C?

Accepted Answer

Hyperthermophile

Question 9

A facultative anaerobe is best described as an organism that:

Accepted Answer

Can grow with or without oxygen but grows better with oxygen.

Question 10

Which of the following is a trace element required by bacteria for enzyme function?

Accepted Answer

Zinc

Question 11

A microbiologist uses a spectrophotometer to estimate bacterial growth. What is being measured?

Accepted Answer

Turbidity (cloudiness) of the culture

Question 12

Which of the following best describes an autotroph?

Accepted Answer

An organism that uses $$CO_2 as $$its carbon source

Question 13

Which of the following equations correctly represents the action of superoxide dismutase?

Accepted Answer

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

Question 14

Which of the following best describes a fastidious bacterium?

Accepted Answer

It requires many organic growth factors from the environment.

Question 15

A microbiologist is culturing anaerobic bacteria. Which of the following methods would be most appropriate?

Accepted Answer

Using an anaerobic growth chamber with hydrogen and a palladium catalyst

Question 16

Which of the following statements about mesophiles is correct?

Accepted Answer

They grow best at temperatures between 25°C and 40°C.

Question 17

Which of the following is NOT an essential macronutrient for microbial growth?

Accepted Answer

Nickel

Question 18

A bacterium is placed in a solution with a higher concentration of NaCl than inside the cell. What is the most likely outcome?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 19

Which of the following best describes the role of nitrogen-fixing bacteria?

Accepted Answer

They convert atmospheric $$N_2$$ into forms usable by living organisms.

Question 20

Which of the following best explains why large volumes of food cool more slowly in a refrigerator, increasing the risk of bacterial growth?

Accepted Answer

The center of the food remains in the 'danger zone' temperature range for a longer period, allowing bacteria like Bacillus cereus to multiply.

Microbial Growth: Nutrition, Environmental Factors, and Measurement

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드