Question 1

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

Accepted Answer

Anabolism builds complex molecules from simpler ones and requires energy, while catabolism breaks down complex molecules into simpler ones and releases energy.

Question 2

During glycolysis, ATP is generated by substrate-level phosphorylation. Which of the following equations best represents substrate-level phosphorylation?

Accepted Answer

$$ ADP + substrate{-}P \rightarrow ATP + substrate $$

Question 3

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes lower the activation energy of a reaction, increasing the reaction rate without being permanently altered.

Question 4

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site, preventing substrate binding.

Question 5

Which of the following is an example of an oxidation-reduction (redox) reaction?

Accepted Answer

$$ NAD^+ + 2e^- + 2H^+ \rightarrow NADH + H^+ $$

Question 6

Which of the following best describes feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway binds to an allosteric site on the first enzyme, decreasing its activity.

Question 7

Which of the following environmental factors would NOT typically increase enzyme activity?

Accepted Answer

Adding a noncompetitive inhibitor.

Question 8

Which pathway of cellular respiration produces the majority of ATP in aerobic organisms?

Accepted Answer

Electron transport chain and oxidative phosphorylation

Question 9

Which of the following statements about fermentation is NOT true?

Accepted Answer

Fermentation requires oxygen to proceed.

Question 10

A microbe is classified as a facultative anaerobe. Which of the following best describes its oxygen requirements?

Accepted Answer

It can grow with or without oxygen, but grows better in the presence of oxygen.

Question 11

Which of the following best explains why high osmotic pressure inhibits microbial growth?

Accepted Answer

It removes water from the cell, causing plasmolysis and inhibiting metabolism.

Question 12

Which of the following best describes a chemically defined medium?

Accepted Answer

A medium in which the exact chemical composition is known.

Question 13

During the log (exponential) phase of bacterial growth, which of the following occurs?

Accepted Answer

Cells are dividing at a constant and maximum rate.

Question 14

If a culture of E. coli is grown under ideal conditions and divides every 20 minutes, how many cells will there be after 1 hour and 40 minutes, starting with 12 cells? Use the formula $$ N = N_0$ 	imes 2^n $$, where $$ n  is $$the number of generations.

Accepted Answer

768 cells

Question 15

Which of the following best describes the mechanism of action for autoclaving as a microbial control method?

Accepted Answer

It uses moist heat under pressure to denature proteins and destroy membranes.

Question 16

Which of the following statements about disinfectants is TRUE?

Accepted Answer

Disinfectants are used on inanimate objects to reduce or eliminate microbial populations.

Question 17

Which of the following is the most effective method for killing bacterial endospores?

Accepted Answer

Autoclaving at 121°C and 15 psi for 15 minutes

Question 18

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization removes all forms of microbial life, while disinfection reduces the number of pathogens to safe levels.

Question 19

A bacterial culture is grown in two flasks: Flask A is incubated aerobically, and Flask B is incubated anaerobically. Both contain glucose-minimal salts broth and are otherwise identical. Which flask will produce more ATP per glucose molecule?

Accepted Answer

Flask A, because aerobic respiration yields more ATP than anaerobic processes.

Question 20

Which of the following best describes the role of ATP as an intermediate between catabolism and anabolism?

Accepted Answer

ATP stores energy released from catabolic reactions and provides energy for anabolic reactions.

Microbial Metabolism, Growth, and Control: Study Guide

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