Mastering Chapter 9

If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA? If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA? 1/6 1/3 2/3 all of it

1/3

How many NADH are produced by glycolysis?

2

Part complete In glycolysis there is a net gain of _____ ATP.

2

In glycolysis, what starts the process of glucose oxidation?

ATP

Which of these enters the citric acid cycle?

Acetyl CoA

Which stage of glucose metabolism produces the most ATP?

Electron transport and chemiosmosis

Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?

Glucose

During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions.

Glucose utilization would increase a lot.

Which step of the cellular respiration pathway can take place in the absence of oxygen?

Glycolysis

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? It allows for an increased rate of the citric acid cycle. It increases the surface for substrate-level phosphorylation. It allows for an increased rate of glycolysis. It increases the surface for oxidative phosphorylation.

It increases the surface for oxidative phosphorylation.

Which of the following statements best describes the primary role played by oxygen in cellular respiration? Which of the following statements best describes the primary role played by oxygen in cellular respiration? It serves as the final acceptor for electrons from the electron transport chain. It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. It oxidizes glucose to form two molecules of pyruvate. It yields energy in the form of ATP as it is passed down the electron transport chain.

It serves as the final acceptor for electrons from the electron transport chain.

A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. What is the most likely way that the lost fat left the body?

It was released as CO2 and H2O.

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

What happens when electrons are passed from one atom to a more electronegative atom?

The more electronegative atom is reduced, and energy is released.

Why are carbohydrates and fats frequently considered high-energy foods?

They contain many electrons associated with hydrogen atoms.

What is the biological significance of the light-independent reactions of photosynthesis?

They convert carbon dioxide to sugar.

True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.

True

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.

True

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

acetyl CoA

Which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of which of the following processes? allosteric regulation active transport a reaction with a positive ΔG coupling of an endergonic reaction to an exergonic reaction

coupling of an endergonic reaction to an exergonic reaction

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

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

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

Water is one of the end products of aerobic respiration. What is the source of the oxygen atom used in formation of the water?

molecular oxygen

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation? oxidation of NADH to NAD+ hydrolysis of ATP to ADP + i reduction of FAD to FADH2 reduction of NAD+ to NADH

oxidation of NADH to NAD+

In cellular respiration, most ATP molecules are produced by _____.

oxidative phosphorylation

The final electron acceptor of cellular respiration is _____.

oxygen

In photosynthetic cells, synthesis of ATP by chemiosmosis occurs during ________.

photosynthesis and respiration

In fermentation _____ is reduced and _____ is oxidized.

pyruvate, NAdH

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

reduced

The basic function of fermentation is

regeneration of NAD+, which allows continued ATP production by glycolysis.

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation

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

2 NADH, 2 pyruvate, and 2 ATP

Products of the Citric Acid Cycle

ATP, CO2, FAdH2, NADh + H+

During aerobic respiration, which of the following molecules directly donates electrons to the electron transport chain at the lowest energy level? During aerobic respiration, which of the following molecules directly donates electrons to the electron transport chain at the lowest energy level? NADH ATP water FADH2

FADH2

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 of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?

It loses electrons and loses potential energy.

P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?

It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

In muscle cells, fermentation produces _____.

lactate and NAD+

How will a healthy individual's ATP production change during an eight-hour fast? How will a healthy individual's ATP production change during an eight-hour fast? The individual's ATP production will decrease significantly. The individual's ATP production will increase significantly. The individual's ATP production will not change significantly.

not change significantly Catabolism can harvest energy from fats in fatty tissue or from storage proteins or glycogen in the liver. As a result, glycolysis and cellular respiration continue to produce ATP during a fast. Read about the diversity of catabolism.

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

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space

Which of the following statements about the electron transport chain is true?

NADH and FADH2 donate their electrons to the chain.

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?

Oxaloacetate will accumulate and citric acid will decrease.

Anaerobic Respiration

Respiration in the absence of oxygen. This produces lactic acid. Final electron acceptor is not oxygen

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain?

The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2. The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.

The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.

Which of the following processes generates a proton-motive force in mitochondria?

pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space

Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration? Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration? glucose → pyruvate → electron transport chain → NADH → ATP glucose → pyruvate → ATP → oxygen glucose → NADH → electron transport chain → oxygen food → glycolysis → citric acid cycle → NADH → ATP

glucose → NADH → electron transport chain → oxygen

What is the relationship between the wavelength of light and the quantity of energy per photon?

inversely related

In the citric acid cycle, ATP molecules are produced by _____.

substrate-level phosphorylation

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

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

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

2 Each glucose produces two pyruvates, each of which is converted into acetyl CoA.

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

6 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle.

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

C6H12O6 is oxidized and O2 is reduced.

What is the basic role of CO2 in photosynthesis?

CO2 is fixed or incorporated into organic molecules.

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?

Carbon dioxide

A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?

Catabolic processes are activated that generate more ATP.