Question 1

Which of the following best distinguishes an organic molecule from an inorganic molecule?

Accepted Answer

Organic molecules contain carbon-hydrogen (C-H) bonds, while inorganic molecules generally do not.

Question 2

A bacterium is found to grow only in the presence of a small amount of oxygen (2-10%) and is inhibited by atmospheric oxygen levels. What is the correct classification for this organism?

Accepted Answer

Microaerophile

Question 3

Which of the following best describes the function of the enzyme catalase in bacteria?

Accepted Answer

It breaks down hydrogen peroxide into water and oxygen.

Question 4

An organism that lacks both superoxide dismutase and catalase is most likely to be classified as:

Accepted Answer

Obligate anaerobe

Question 5

Which of the following is a growth factor for bacteria?

Accepted Answer

Nicotinamide adenine dinucleotide (NAD^+)

Question 6

Nitrogen fixation is best described as:

Accepted Answer

The conversion of atmospheric nitrogen ($$N_2) $$into ammonia ($$NH_3) by $$certain prokaryotes.

Question 7

A bacterium has cardinal temperatures of minimum 10°C, optimum 37°C, and maximum 45°C. How would you classify this organism based on temperature preference?

Accepted Answer

Mesophile

Question 8

Which of the following best describes a biofilm?

Accepted Answer

A community of microorganisms encased in a self-produced matrix of polysaccharides, proteins, and DNA attached to a surface.

Question 9

Which of the following is NOT a basic ecological relationship among microorganisms?

Accepted Answer

Osmosis

Question 10

Which statement best explains the difference between prokaryotic and eukaryotic growth?

Accepted Answer

Prokaryotic growth is typically measured by increase in cell number, while eukaryotic growth can be measured by both cell size and number.

Question 11

Which kingdom's organisms are typically measured for growth by increase in cell number rather than size?

Accepted Answer

Monera (Bacteria)

Question 12

What is the name for the process of cell division in prokaryotes?

Accepted Answer

Binary fission

Question 13

During which phase of the bacterial growth curve are cells most susceptible to antibiotics that target cell wall synthesis?

Accepted Answer

Log (exponential) phase

Question 14

At 8:00 am, you inoculate a broth with 10 actively dividing bacterial cells. At 12:00 pm, there are 2,560 cells. What is the generation time of the bacteria in this culture? (Assume exponential growth.)

Accepted Answer

$$n = \frac{\log N_t - \log N_0$}{\log 2}$$, $$N_0 = 10$, N_t = 2560$, t = 4$ hours, so n = 8$ generations, generation time g$$ = \frac{4}{8} = 0.5$$ hours = 30 minutes.

Question 15

Which of the following best describes the difference between turbidity and colonies as measures of microbial growth?

Accepted Answer

Turbidity measures cloudiness in a liquid culture (total cell mass), while colonies represent individual viable cells growing on solid media.

Question 16

Which of the following best defines aseptic technique?

Accepted Answer

A set of practices to prevent contamination of cultures, the environment, and personnel.

Question 17

Which type of culture media would you use to isolate individual bacterial colonies from a mixed sample?

Accepted Answer

Plate (solid) media

Question 18

Which of the following is a direct method for measuring microbial growth?

Accepted Answer

Counting colonies on a plate (plate count method)

Question 19

Which of the following is a component commonly found in plate media for bacterial culture?

Accepted Answer

Agar

Question 20

A spectrophotometer is used in microbiology to:

Accepted Answer

Measure the optical density (turbidity) of a culture, which correlates with cell mass.

Microbial Nutrition and Growth: Study Guide (Chapter 6)

Study Guide - Practice Questions

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