Question 1

Which of the following best describes the difference between catabolism and anabolism in microbial metabolism?

Accepted Answer

Catabolism involves the breakdown of complex molecules to release energy, while anabolism uses energy to build complex molecules from simpler ones.

Question 2

During aerobic respiration, which molecule acts as the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen ($O_2$)

Question 3

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of a reaction, increasing the rate at which the reaction occurs.

Question 4

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site of the enzyme, preventing substrate binding.

Question 5

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

The direct transfer of a phosphate group from a phosphorylated compound to ADP to form ATP.

Question 6

Which of the following is NOT a product of glycolysis?

Accepted Answer

Oxygen ($O_2$)

Question 7

A bacterium is found to grow only in the absence of oxygen and dies when exposed to it. This organism is best classified as a(n):

Accepted Answer

Obligate anaerobe

Question 8

Which of the following equations correctly represents the net ATP yield from aerobic respiration of one molecule of glucose in prokaryotes?

Accepted Answer

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38ATP$

Question 9

Which of the following best explains why obligate aerobes require oxygen for growth?

Accepted Answer

Oxygen serves as the final electron acceptor in their electron transport chain.

Question 10

A microbiologist is measuring the growth of a bacterial culture. If the initial population is $1 	imes 10^3$ cells and the population doubles every 30 minutes, how many cells will there be after 2 hours?

Accepted Answer

$1.6 	imes 10^4$

Question 11

Which of the following statements about the use of selective and differential media is correct?

Accepted Answer

Selective media inhibit the growth of some organisms while allowing others to grow; differential media distinguish between organisms based on metabolic characteristics.

Question 12

Which of the following best describes the function of ATP in microbial cells?

Accepted Answer

ATP stores and transfers energy for cellular processes.

Question 13

Which of the following is a correct pairing of energy and carbon sources for a photoautotroph?

Accepted Answer

Light as energy source, $CO_2$ as carbon source

Question 14

Which of the following best explains the difference between anabolism and catabolism?

Accepted Answer

Anabolism builds complex molecules using energy, while catabolism breaks down molecules to release energy.

Question 15

Which of the following is a trace element required by some enzymes as a cofactor?

Accepted Answer

Zinc ($Zn^{2+}$)

Question 16

A facultative anaerobe is best described as an organism that:

Accepted Answer

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

Question 17

Which of the following best describes the process of chemiosmosis in ATP generation?

Accepted Answer

The movement of protons across a membrane through ATP synthase, driving the synthesis of ATP.

Question 18

Which of the following is a correct description of the lag phase in a bacterial growth curve?

Accepted Answer

Cells are metabolically active but not dividing rapidly as they adjust to new conditions.

Question 19

Which of the following best explains why obligate anaerobes are killed by oxygen?

Accepted Answer

They lack enzymes such as superoxide dismutase and catalase to detoxify reactive oxygen species.

Question 20

Which of the following best describes the function of NAD$^+$ in cellular respiration?

Accepted Answer

It acts as an electron carrier, accepting electrons during glycolysis and the Krebs cycle.

Exam #3

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