Question 1

In the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$, which species is being reduced?

Accepted Answer

Pyruvate

Question 2

Which statement best describes the role of pyruvate in the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$?

Accepted Answer

Pyruvate is the oxidizing agent because it accepts electrons.

Question 3

Using the acronym OILRIG, which process is occurring to NADH in the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$?

Accepted Answer

NADH is being oxidized (losing electrons).

Question 4

In a biological context, why is the conversion of pyruvate to lactate important during anaerobic respiration?

Accepted Answer

It regenerates NAD$^+$, which is required for glycolysis to continue.

Question 5

Which of the following best describes the function of an oxidizing agent in a redox reaction?

Accepted Answer

It gains electrons and is reduced.

Question 6

Given the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$, which species is the reducing agent?

Accepted Answer

NADH

Question 7

If a molecule is reduced in a chemical reaction, what happens to its oxidation state?

Accepted Answer

It decreases.

Question 8

Which of the following is a correct application of the OILRIG acronym?

Accepted Answer

Oxidation is loss of electrons, reduction is gain of electrons.

Question 9

In the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$, what is the fate of the electrons from NADH?

Accepted Answer

They are transferred to pyruvate, reducing it to lactate.

Question 10

Which of the following statements is TRUE regarding agents in redox reactions?

Accepted Answer

The oxidizing agent is reduced by accepting electrons.

Question 11

A student claims that in the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$, lactate is the oxidizing agent. Which reasoning best refutes this claim?

Accepted Answer

Lactate is formed by reduction of pyruvate, so pyruvate is the oxidizing agent.

Question 12

In a metabolic pathway, why is it important to correctly identify the oxidizing and reducing agents?

Accepted Answer

It helps predict the direction of electron flow and energy changes.

Question 13

Which of the following best explains why electrons are considered to have a negative charge in redox reactions?

Accepted Answer

Adding electrons reduces the overall charge of a species.

Question 14

During intense exercise, muscle cells convert pyruvate to lactate. What is the primary chemical reason for this conversion?

Accepted Answer

To regenerate NAD$^+$ for continued glycolysis.

Question 15

Which of the following is NOT a correct description of the process occurring in $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$?

Accepted Answer

NAD$^+$ is reduced to NADH.

Question 16

A scientist wants to increase the rate of NAD$^+$ regeneration in a cell. Which reaction should they promote?

Accepted Answer

$	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$

Question 17

Which of the following is a common misconception about redox agents?

Accepted Answer

The oxidizing agent is always the species that is oxidized.

Question 18

In the context of cellular respiration, which molecule acts as the electron donor in the conversion of pyruvate to lactate?

Accepted Answer

NADH

Question 19

Which of the following best describes the change in oxidation state for pyruvate in the reaction $	ext{Pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{Lactate} + 	ext{NAD}^+$?

Accepted Answer

Pyruvate's oxidation state decreases.

Redox Reactions and Oxidizing/Reducing Agents in Biochemical Contexts

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