Chapter 9 Practice Questions

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.

creation of a proton-motive force

The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.

how ATP is synthesized by a proton motive force

In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP?

energy released from movement of protons through ATP synthase, down their electrochemical gradient

During aerobic respiration, electrons travel downhill in which sequence?

glucose → NADH → electron transport chain → oxygen

Which of the following normally occurs regardless of whether or not oxygen (O2) is present?

glycolysis

Which of the following occurs in the cytosol of a eukaryotic cell?

glycolysis and fermentation

Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.

2 NADH, 2 pyruvate, and 2 ATP

If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle?

2/3

Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)?

3 ATP, 6 CO2, 9 NADH, and 3 FADH2

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

30-32

For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?

4

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of _____.

allosteric regulation

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?

molecular oxygen (O2)

One function of both alcohol fermentation and lactic acid fermentation is to _____.

oxidize NADH to NAD+

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.

oxidized

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes _____.

reduced

Most of the CO2 from the catabolism of glucose is released during _____.

the citric acid cycle

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

the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

In glycolysis, for each molecule of glucose oxidized to pyruvate _____.

two molecules of ATP are used and four molecules of ATP are produced.

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____.

ATP, CO2, and ethanol (ethyl alcohol)

If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?

14

Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

Acetyl CoA

Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidized and O2 is reduced.

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

FADH2

The electron transport chain _____.

Is a series of redox reactions

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

It increases the surface for oxidative phosphorylation.

Which of the following statements about NAD+ is true?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

Which electron carrier(s) function in the citric acid cycle?

NADH and FADH2

If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production?

The rates of ATP production and carbon dioxide production would both increase

The oxygen consumed during cellular respiration is involved directly in which process or event?

accepting electrons at the end of the electron transport chain

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. The three listed steps result in the formation of _____.

acetyl CoA, NADH, and CO2

The primary role of oxygen in cellular respiration is to _____.

act as an acceptor for electrons and hydrogen, forming water

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, when electron transfer and ATP synthesis still occur, what must be present?

all of the electron transport proteins and ATP synthase

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____.

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____.

loses electrons and loses potential energy

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle