Redox Reactions

Oxidation is the _________________________, and reduction is the _________________________.

a) Gain of electrons; Loss of electrons.

b) Gain of protons; Loss of protons. 

c)  Loss of electrons; Gain of electrons.

d)  Gain of oxygen; Loss of oxygen.

When glucose donates electrons to NAD⁺ creating NADH, the glucose molecule becomes:

a) Hydrolyzed.

b) Oxidized.

c) Neutral.

d) Reduced.

An electron carrier before it harvests energy from glucose molecules in a series of gradual steps is:

a) Pyruvate.

b) AMP.

c) ATP.

d) NAD⁺.

e) NADH.

Which one of the following molecules is a by-product of cellular respiration?

a) Water.

b) Glucose.

c) Pyruvate.

d) Oxygen.

e) ADP.

Which of the summary statements below describes the results of the following reaction?

C₆H₁₂O₆ + 6 O₂ → 6 H₂O + Energy

a) C₆H₁₂O₆ is oxidized and O₂ is reduced.

b) O₂ is oxidized and H₂O is reduced.

c) CO₂ is reduced and O₂ is oxidized.

d) O₂ is reduced and CO₂ is oxidized.

Based on the map of cellular respiration, why do we need to breathe in oxygen?

a) Oxygen is the final electron acceptor for lactic acid fermentation.

b) Oxygen is the final electron acceptor for alcohol fermentation.

c) Oxygen is the final electron acceptor for aerobic cellular respiration.

d) Oxygen is not important for the purposes of cellular respiration.

Substrate-level phosphorylation is utilized to create ATP in which steps of aerobic cellular respiration?

a) Electron Transport Chain and Chemiosmosis.

b) Glycolysis and Pyruvate Oxidation.

c) Pyruvate Oxidation and Krebs cycle.

d) Glycolysis and Krebs cycle.

Which type of phosphorylation synthesizes ATP using an enzyme that transfers a phosphate group to ADP?

a) Adaptive Phosphorylation. 

b) Oxidative Phosphorylation. 

c) Substrate-level Phosphorylation.

d) Product-level Phosphorylation.

The largest amount of ATP made by cellular respiration is created by the process of ______________, in the _____________ steps of aerobic cellular respiration.

a) Substrate-level phosphorylation; first.

b) Oxidative phosphorylation; first.

c) Oxidative phosphorylation; final.

d) Substrate-level phosphorylation; final.

Where does the first stage of aerobic cellular respiration take place within a cell?

a) Mitochondrial matrix.

b) Inner mitochondrial membrane.

c) Intermembrane space.

d) Cytoplasm.

Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products?

a) 2 NAD⁺, 2 pyruvate, and 2 ATP.

b) 2 NADH, 2 pyruvate, and 2 ATP.

c) 4 NADH, 2 pyruvate, and 4 ATP.

d) 6 CO₂, 2 pyruvate, and 2 ATP.

Which of the following is a result of glycolysis?

a) A net gain of four ATP per one glucose molecule.

b) Conversion of FAD to FADH₂.

c) Conversion of one glucose molecule to two pyruvate molecules.

d) Conversion of NADH to NAD⁺.

Each of the following describes the pyruvate oxidation reaction except that _____________________.

a) It connects glycolysis to the citric acid cycle.

b) Each pyruvate is converted to an acetyl-CoA molecule.

c) NAD⁺ is reduced to NADH.

d) This reaction occurs within the cytoplasm.

e) Carbon dioxide is released as a by-product.

In aerobic cellular respiration, pyruvate molecules must be transformed through a process called pyruvate oxidation before they can be broken down in the Krebs Cycle. What are the products of pyruvate oxidation?

a) Acetyl CoA, O₂, and ATP.

b) Acetyl and CO₂.

c) Acetyl CoA, FADH₂, and CO₂.

d) Acetyl CoA, NADH, and CO₂.

e) Acetyl CoA, NAD⁺, ATP, and CO₂.

Which product of the Krebs cycle is also used as a reactant in the Krebs cycle?

a) Citrate.

b) ATP.

c) Acetyl-CoA.

d) Oxaloacetate.

Taking one molecule of glucose through glycolysis, pyruvate oxidation, and the Krebs cycle generates:

a) 6 CO₂, 8 NADH, 2 FADH₂ and 4 ATP.

b) 6 CO₂, 8 NADH, 1 FADH₂ and 2 ATP. 

c)  6 CO₂, 10 NADH, 2 FADH₂ and 4 ATP.  

d) 6 CO₂, 10 NADH, 2 FADH₂ and 2 ATP.

In the electron transport chain, the final electron acceptor is:

a) H₂O.

b) CO₂.

c) H₂O.

d) O₂.

e) NAD⁺.

Which of the following events takes place in the electron transport chain?

a) The breakdown of glucose into six carbon dioxide molecules.

b) The breakdown of NADH and FADH₂ to carbon dioxide.

c) Harnessing energy from high-energy electrons derived from glycolysis, pyruvate oxidation, and the Krebs cycle.

d) Substrate-level phosphorylation.

Chemiosmotic creation of ATP is driven by:

a) Phosphate transfer through the plasma membrane.

b) Potential energy of the H⁺ concentration gradient created by the electron transport chain.

c) Substrate-level phosphorylation in the mitochondrial matrix.

d) Large quantities of ADP in the mitochondrial matrix.

The electron transport chain pumps H⁺ ions into which location of the mitochondria?

a) Mitochondrial intermembrane space. 

b) Mitochondrial matrix.

c)  Mitochondrial inner membrane.

d) The H⁺ ions are pumped out of the mitochondria.

Through the first three stages of cellular respiration only 4 ATP molecules have been produced from the initial glucose molecule. In which of the products of these stages is the potential energy to produce more ATP molecules stored?

a) The 6 molecules of CO₂.

b) The H⁺ ions produced.

c) The 10 NADH and 2 FADH₂ molecules.

d) The 4 molecules of ATP.

Water is one of the products of aerobic cellular respiration. What is the source of the oxygen atom utilized to create the water molecules?

a) Carbon dioxide (CO₂).

b) Glucose (C₆H₁₂O₆).

c) Oxygen gas (O₂).

d) Pyruvate (C₃H₃O₃^–).

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C₆H₁₂O₆) through the process of aerobic cellular respiration?

a) 4.

b) 2.

c) 26-34.

d) 30-38.

Fermentation allows a cell to:

a) Recycle NADH to NAD⁺ for glycolysis.

b) Use NADH as a terminal electron acceptor.

c) Reduce NAD⁺ to NADH for glycolysis.

d) Synthesize ATP via ATP synthase.

Which of the following describes a primary function of both lactic acid fermentation and alcohol fermentation?

a) Reduction of NAD⁺ to NADH.

b) Oxidation of NADH to NAD⁺.

c) Reduction of FAD to FADH₂.

d)  Hydrolysis of ATP to ADP.

In which of the steps of aerobic and anaerobic cellular respiration does substrate-level phosphorylation occur?

a) In glycolysis only.

b) In the Krebs cycle only.

c) In the electron transport chain only.

d) In both glycolysis and the Krebs cycle.

e) In both the Krebs cycle and the electron transport chain.

Which of the following statements about NAD⁺ is true?

a) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the Krebs cycle.

b) NAD⁺ has more chemical energy than NADH.

c) NAD⁺ donates high energy electrons to the electron transport chain.

d) In the absence of NAD⁺, glycolysis can still function.