$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} \rightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + \text{energy}$$

Question 1

Which of the following best describes the role of NAD+ in cellular respiration?

Accepted Answer

NAD+ is an electron carrier that is reduced to NADH during glycolysis and the Krebs cycle.

Question 2

During glycolysis, what is the net yield of ATP and NADH per molecule of glucose?

Accepted Answer

2 ATP and 2 NADH

Question 3

Which enzyme is responsible for the key regulatory step in glycolysis and is inhibited by ATP and citrate?

Accepted Answer

Phosphofructokinase

Question 4

What is the correct balanced equation for aerobic cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} ightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + 	ext{energy}$$

Question 5

In the absence of oxygen, how is NAD+ regenerated in animal cells?

Accepted Answer

By converting pyruvate to lactate

Question 6

Which of the following reactions represents the reduction of NAD+?

Accepted Answer

$$\mathrm{NAD^+} + 2\mathrm{H^+} + 2e^- \rightarrow \mathrm{NADH} + \mathrm{H^+}$$

Question 7

Which process occurs in the cytoplasm and does not require oxygen?

Accepted Answer

Glycolysis

Question 8

What is the fate of pyruvate under aerobic conditions in eukaryotic cells?

Accepted Answer

It is converted to acetyl-CoA in the mitochondria.

Question 9

Which molecule enters the Krebs cycle by combining with oxaloacetate to form citrate?

Accepted Answer

Acetyl-CoA

Question 10

During substrate-level phosphorylation in glycolysis, which molecule donates a phosphate group to ADP?

Accepted Answer

A phosphorylated intermediate

Question 11

Which of the following is a product of the Krebs cycle per turn (per acetyl-CoA)?

Accepted Answer

2 NADH, 1 FADH$$_2$$, 1 GTP, 2 CO$$_2$$

Question 12

Which statement best explains why glycolysis is considered an ancient metabolic pathway?

Accepted Answer

It occurs in the cytoplasm and does not require oxygen, making it universal among cells.

Question 13

Which of the following best describes feedback inhibition in glycolysis?

Accepted Answer

Accumulation of ATP and citrate inhibits phosphofructokinase, slowing glycolysis.

Question 14

Which of the following is true regarding the oxidation of pyruvate?

Accepted Answer

Pyruvate is converted to acetyl-CoA, CO$$_2$$, and NADH in the mitochondria.

Question 15

Which of the following is a correct description of a redox reaction in cellular respiration?

Accepted Answer

A substrate is oxidized, losing electrons, while NAD+ is reduced, gaining electrons.

Question 16

Which of the following best explains the importance of electron carriers in cellular respiration?

Accepted Answer

They shuttle electrons from glucose oxidation to reduce other molecules, enabling ATP production.

Question 17

A patient with a genetic defect in phosphofructokinase would most likely experience which of the following?

Accepted Answer

Impaired conversion of glucose to pyruvate, leading to reduced ATP production.

Question 18

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is generated directly from the transfer of a phosphate group from a high-energy substrate to ADP.

Question 19

Which of the following is NOT a product of fermentation in yeast cells?

Accepted Answer

Lactate

Question 20

Which molecule is regenerated at the end of the Krebs cycle to allow the cycle to continue?

Accepted Answer

Oxaloacetate

Glycolysis and Krebs Cycle: Energy Production in Living Systems

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