Q: A cell hydrolyzes ATP to ADP and inorganic phosphate. What is the standard free energy change ($$\Delta G^\circ') $$for this reaction?

$$\Delta G^\circ' = -31.8\ \text{kJ/mol}$$

Question 1

Which of the following best describes the main function of the redox tower in microbial metabolism?

Accepted Answer

It ranks electron carriers based on their reduction potential, indicating which compounds are better electron donors or acceptors.

Question 2

A cell hydrolyzes ATP to ADP and inorganic phosphate. What is the standard free energy change ($$\Delta G^\circ') $$for this reaction?

Accepted Answer

$$\Delta G^\circ' = -31.8\ 	ext{kJ/mol}$$

Question 3

Which of the following molecules is NOT considered an energy-rich compound in cells?

Accepted Answer

Glucose 6-phosphate

Question 4

During glycolysis, which step is responsible for substrate-level phosphorylation?

Accepted Answer

The transfer of a phosphate group from phosphoenolpyruvate to ADP to form ATP.

Question 5

Which of the following best explains why glycolysis alone is insufficient to sustain life in most cells?

Accepted Answer

It does not achieve redox balance, leading to an accumulation of NADH.

Question 6

In the transition reaction, what are the products generated from one molecule of pyruvate?

Accepted Answer

1 NADH, 1 CO$$_2$$, and 1 Acetyl-CoA

Question 7

Which of the following is a key function of the citric acid cycle (TCA cycle) in addition to energy production?

Accepted Answer

Providing precursors for amino acid and fatty acid biosynthesis

Question 8

A bacterium uses the following redox couples: MnO$$_2/Mn$^{2+}$$ ($$E_0$$' = +0.40$$ V) and FeOOH/Fe$$^{2+}$$ (E_0$' = +0.17 V). $$Which compound acts as the electron donor?

Accepted Answer

Fe$$^{2+}$$

Question 9

Which of the following equations correctly represents the calculation of free energy change ($$\Delta G^\circ') $$for a redox reaction using standard reduction potentials?

Accepted Answer

$$\Delta G^\circ' = -nF\Delta E_0$'$$

Question 10

Which of the following statements about substrate-level phosphorylation is correct?

Accepted Answer

It involves the direct transfer of a phosphate group from a high-energy substrate to ADP to form ATP.

Question 11

Which molecule is produced in the greatest quantity per molecule of glucose during the combined processes of glycolysis, transition reaction, and the TCA cycle?

Accepted Answer

NADH

Question 12

What is the main role of the glyoxylate cycle in bacteria growing on acetate as a carbon source?

Accepted Answer

To regenerate oxaloacetate for the citric acid cycle and enable biosynthesis from C2 compounds

Question 13

Which of the following best describes the function of NADH in cellular metabolism?

Accepted Answer

It acts as a mobile electron carrier, transferring reducing power to the electron transport chain.

Question 14

A mutation in a bacterium prevents the formation of succinyl-CoA. Which biosynthetic process would be most directly affected?

Accepted Answer

Synthesis of cytochromes and chlorophyll

Question 15

Which of the following is a defining feature of oxidative phosphorylation?

Accepted Answer

ATP synthesis is driven by a proton motive force generated by electron transport.

Question 16

During the TCA cycle, which step directly results in the production of GTP (or ATP) via substrate-level phosphorylation?

Accepted Answer

Conversion of succinyl-CoA to succinate

Question 17

Which of the following best explains why the cell must regenerate NAD$$^+$$ during metabolism?

Accepted Answer

To maintain redox balance and allow glycolysis and the TCA cycle to continue

Question 18

A chemoorganotroph is growing on glucose. Which of the following pathways is NOT directly involved in the complete oxidation of glucose to CO$$_2$$?

Accepted Answer

Glyoxylate cycle

Question 19

Which of the following statements about enzymes is correct?

Accepted Answer

They lower the activation energy of biochemical reactions without being consumed.

Lecture 9 Microbio

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