Ch. 9: Cellular Respiration and Fermentation

The following metabolic pathways produce(s) the most ATP, per glucose molecule metabolized, during cellular respiration:

The electron transport chain and oxidative phosphorylation

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.

Enables the cell to recycle the reduced NADH to oxidized NAD⁺

Muscle tissues make lactate from pyruvate to do what?

regenerate NAD⁺

A molecule becomes more oxidized when it __________.

loses an electron

The energy from the electrons in NADH and FADH₂ fuel what process in the electron transport chain?

The pumping of H⁺ across the cristae of the mitochondrion

During aerobic respiration, molecular oxygen (O₂) is used for which of the following purposes?

At the end of the electron transport chain to accept electrons and form H₂O

What is the total production of ATP, NADH, and FADH₂ in the citric acid cycle from one molecule of glucose?

Two ATP, six NADH, and two FADH₂

A small amount of ATP is made in glycolysis by which of the following processes?

Transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation

Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O₂) and produces CO₂?

The combination of the citric acid cycle and electron transport

What is the role of oxygen in the electron transport chain?

It is reduced to form water.

Glucose is the primary fuel for cellular respiration. Which of the following molecules an also be used by cellular respiration to generate ATP?

• Glycerol

• Amino acids

• Fatty acids

During the energy payoff phase of glycolysis, __________.

NADH and ATP are produced

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes?

Reducing NAD+ to NADH in glycolysis and the citric acid cycle AND producing a proton gradient for ATP synthesis in the mitochondria.

In which process is glucose oxidized to form two molecules of pyruvate?

Glycolysis

The ATP synthase in a human cell obtains energy for synthesizing ATP directly from which of the following processes?

The flow of H⁺ across the inner mitochondrial membrane through the ATP synthase enzyme

Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration?

Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation

Cells must regulate their metabolic pathways so that they do not waste resources. What is the most common mechanism that regulates cellular respiration in most cells?

Feedback inhibition of glycolysis

Which statement correctly describes the difference between alcohol fermentation and lactic acid fermentation?

Lactic acid fermentation produces lactate, and alcohol fermentation produces ethanol.

The function of cellular respiration is to __________.

extract usable energy from glucose

Most of the ATP in cellular respiration is produced by the process of chemiosmosis. How does this process produce ATP?

H⁺ flows across the inner mitochondrial membrane through the enzyme ATP synthase.

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes?

The citric acid cycle

The citric acid cycle does not occur in the cytosol. The citric acid cycle functions as a metabolic furnace that oxidizes organic fuel derived from pyruvate. Pyruvate is broken down to three CO₂ molecules, including the molecule of CO₂ released during the conversion of pyruvate to acetyl CoA. The cycle generates one ATP per turn by substrate-level phosphorylation, but most of the chemical energy is transferred to NAD⁺ and a related electron carrier, the coenzyme FAD (flavin adenine dinucleotide, which is derived from riboflavin, a B vitamin), during the redox reactions. The total yield per glucose from the citric acid cycle is six NADH molecules, two FADH₂ molecules, and the equivalent of two ATP molecules. This pathway occurs in the matrix of the mitochondrion.

Glycolysis occurs in the cytosol.

 

The electron transport chain occurs on the cristae of the mitochondrion.

 

Oxidative phosphorylation occurs in the mitochondrion.

In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.

glucose; oxygen

All of the processes involved in cellular respiration produce ATP. Which of the following processes produces the most ATP?

Oxidative phosphorylation

During the energy investment phase of glycolysis, __________.

glucose is phosphorylated before it is split into two three-carbon molecules

Fermentation by itself produces no ATP but keeps glycolysis going, which produces a small amount of ATP. How does fermentation do this?

Fermentation oxidizes NADH to NAD⁺, which facilitates the production of ATP in glycolysis.

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD⁺ to an NADH.

In what molecule(s) is the majority of the chemical energy from pyruvate transferred during the citric acid cycle?

NADH and FADH₂

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

Glycolysis

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________.

NADH

Which of the following pairs of pathways and their location in the cell is incorrectly matched?

Citric acid cycle: cytosol

The process in which glucose is oxidized to generate two molecules of pyruvate and in which ATP and NADH are produced

Glycosis

There is no production of carbon dioxide in glycolysis. Which of the following is the best explanation for this fact?

The products of glycolysis contain the same total number of carbon atoms as in the starting material.

Which of the following molecules in the process of glycolysis possesses the most chemical energy?

Fructose-1,6-bisphosphate

In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH₂ are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH₂ are produced in the citric acid cycle?

Two ATP, six NADH, two FADH₂

Where do the reactions of the citric acid cycle occur in eukaryotic cells?

The matrix of the mitochondrion

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?

There is a net gain of two ATP from glycolysis and one from each molecule of acetyl CoA oxidized in the citric acid cycle for a total of four per glucose.

Most of the electrons removed from glucose by cellular respiration are used for what processes?

Reducing NAD⁺ to NADH in glycolysis and the citric acid cycle

Producing a proton gradient for ATP synthesis in the mitochondria

What substance(s) is/are involved in oxidative phosphorylation?

ATP

Oxygen

ADP

In eukaryotic cells, the components of the electron transport chain are located in or on __________.

inner membrane of the mitochondrion