Q: Enzymes lower the activation energy of a reaction. Which equation best represents the change in activation energy ($E_a$) due to the presence of an enzyme?

$E_{a,enzyme} = E_{a,without\\ enzyme} - \\Delta E$

Question 1

Which of the following statements best describes the ultimate function of microbial metabolism?

Accepted Answer

To reproduce the organism

Question 2

Which process is exergonic and results in the breakdown of complex molecules into simpler ones?

Accepted Answer

Catabolism

Question 3

What is the role of ATP in cellular metabolism?

Accepted Answer

It stores energy for anabolic reactions

Question 4

Which of the following best describes the relationship between catabolism and anabolism?

Accepted Answer

Catabolism provides energy and precursor molecules for anabolism

Question 5

Enzymes lower the activation energy of a reaction. Which equation best represents the change in activation energy ($E_a$) due to the presence of an enzyme?

Accepted Answer

$E_{a,enzyme} = E_{a,without\ enzyme} - \Delta E$

Question 6

Which of the following is TRUE regarding competitive inhibition of enzymes?

Accepted Answer

The inhibitor competes with the substrate for the active site

Question 7

During glycolysis, what is the net gain of ATP molecules per molecule of glucose?

Accepted Answer

Two ATP

Question 8

Which of the following is the correct sequence of stages in cellular respiration?

Accepted Answer

Synthesis of acetyl-CoA, Krebs cycle, Electron transport chain

Question 9

Which equation best represents substrate-level phosphorylation during glycolysis?

Accepted Answer

$ADP + P_i \rightarrow ATP$

Question 10

In the electron transport chain, what is the primary function of the series of carrier molecules?

Accepted Answer

To pass electrons to the final electron acceptor and pump protons across the membrane

Question 11

Which of the following is a correct description of fermentation?

Accepted Answer

Partial oxidation of sugar using an organic molecule as the final electron acceptor

Question 12

Which type of organism uses inorganic molecules as an energy source and CO$_2$ as a carbon source?

Accepted Answer

Chemoautotroph

Question 13

Which toxic form of oxygen is most likely to cause irreparable damage to cells due to its high reactivity?

Accepted Answer

Hydroxyl radical

Question 14

Nitrogen fixation is essential for life on Earth because:

Accepted Answer

It converts atmospheric nitrogen into forms usable for biosynthesis

Question 15

Which of the following best describes a facultative anaerobe?

Accepted Answer

Can grow with or without oxygen

Question 16

Which equation best represents the effect of temperature on enzyme activity, assuming $V_{max}$ is the maximum rate and $T$ is temperature?

Accepted Answer

$V_{max}$ increases with $T$ up to an optimum, then decreases due to denaturation

Question 17

Which type of microorganism would most likely thrive in a hot spring with temperatures above 80°C?

Accepted Answer

Hyperthermophile

Question 18

What is the effect of a hypertonic solution on most microbial cells?

Accepted Answer

Cells lose water and shrink due to osmosis

Question 19

Which of the following best describes a biofilm?

Accepted Answer

A complex community of microorganisms adhering to a surface and embedded in an extracellular matrix

Question 20

During which phase of the microbial growth curve do cells divide at the fastest rate?

Accepted Answer

Log (exponential) phase

Microbial Metabolism, Nutrition, and Growth: Study Notes

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