Q: Which of the following equations correctly calculates the generation time for a bacterial culture?

$$\text{Generation time} = \frac{\text{Growth time (in minutes)}}{\text{Number of generations}}$$

Question 1

Which microbial growth process is depicted in the first image (showing two connected rod-shaped cells with duplicated genetic material)?

Accepted Answer

Binary fission

Question 2

A hospital patient develops a persistent infection on a catheter. Which microbial community structure is most likely responsible for the difficulty in treating this infection?

Accepted Answer

Biofilm

Question 3

Which phase of the bacterial growth curve (as shown in the fourth image) is characterized by an equal rate of cell division and cell death?

Accepted Answer

Stationary phase

Question 4

A yeast cell reproducing by forming a small outgrowth on one side, as shown in the second image, is undergoing which process?

Accepted Answer

Budding

Question 5

Which of the following best describes a microbe that grows optimally at human body temperature (37°C), as indicated by the thermometer in the fifth image?

Accepted Answer

Mesophile

Question 6

A bacterium that can survive in the Dead Sea is most likely a:

Accepted Answer

Halophile

Question 7

Which enzyme is responsible for converting superoxide ions to hydrogen peroxide in aerobic microbes?

Accepted Answer

Superoxide dismutase

Question 8

A microbe that grows only at the top of a thioglycolate tube (as shown in the oxygen classification image) is classified as a(n):

Accepted Answer

Obligate aerobe

Question 9

Which of the following equations correctly calculates the generation time for a bacterial culture?

Accepted Answer

$$	ext{Generation time} = \frac{	ext{Growth time (in minutes)}}{	ext{Number of generations}}$$

Question 10

Which nutritional category describes an organism that uses light for energy and CO$$_2 as a $$carbon source?

Accepted Answer

Photoautotroph

Question 11

Which phase of the bacterial growth curve is most sensitive to antibiotics and radiation?

Accepted Answer

Log phase

Question 12

A bacterium that grows throughout a thioglycolate tube but does not use oxygen for metabolism is best classified as:

Accepted Answer

Aerotolerant anaerobe

Question 13

Which of the following best describes the process shown in the third image (conidiophore and conidia)?

Accepted Answer

Fungal spore formation

Question 14

Which of the following is NOT a macronutrient required by microbes?

Accepted Answer

Vitamin B12

Question 15

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

Accepted Answer

Acidophile

Question 16

Which of the following statements about bacterial endospores is TRUE?

Accepted Answer

They are thick-walled, nongrowing structures formed by some bacteria.

Question 17

Which of the following best explains why bacteria in biofilms are more resistant to antibiotics than planktonic bacteria?

Accepted Answer

Biofilms provide a protective matrix that limits antibiotic penetration.

Question 18

A microbe that uses organic molecules for both energy and carbon is classified as a:

Accepted Answer

Chemoheterotroph

Question 19

Which of the following is a real-world example of a facultative anaerobe found in the human body?

Accepted Answer

Staphylococcus aureus

Question 20

If a bacterial culture starts with 1,000 cells and has a generation time of 30 minutes, how many cells will there be after 2 hours of exponential growth? Use the formula $$N = N_0$ 	imes 2^n$$, where $$n = \frac{	ext{total time}}{	ext{generation time}}.$$

Accepted Answer

16,000

Fundamentals of Microbial Growth: Structured Study Notes ch. 7

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