Biology 121 Chapter 7

Once they have been processed through the citric acid cycle, the acetyl-CoA molecules from a single glucose molecule will produce:

2 ATP, 6 NADH, 4 CO2.

Consulting Figure 7.1 if necessary, during which stage(s) of cellular respiration is(are) carbon dioxide released?

2 and 3

The breakdown of one glucose molecule during glycolysis results in 2 molecules of pyruvate, which are then oxidized to 2 molecules of acetyl-CoA, and these, in turn, are substrates for the citric acid cycle. If all three fatty acids of a triacylglycerol molecule (a fat molecule) are palmitic acid (C16, having 16 carbons), how many acetyl-CoA molecules would result from beta-oxidation of all of these fatty acids?

24

The approximate yield of ATP from the full oxidation of a molecule of glucose is:

32

Which best describes energy production during cellular respiration?

A small amount of energy is produced by substrate level phosphorylation; most is produced by oxidative phosphorylation.

When a single pyruvate is converted to acetyl-CoA, the other products of the reaction are:

NADH and CO2

The majority of energy generated in the citric acid cycle is in the form of:

energy electrons donated to NAD^+ and FADH.

By the time pyruvate is formed, most of the energy contained in glucose has been released.

false

During the action of ATP synthase, the kinetic energy of the proton gradient is transformed into potential energy.

false

Fermentation produces nearly two times as much ATP as aerobic respiration, which explains why it is a preferred pathway for bacteria.

false

In a plant cell, all stages of cellular respiration are carried out in the cytoplasm.

false

Like glycolysis, acetyl-CoA synthesis produces both pyruvate and acetyl-CoA. These two products feed directly into the citric acid cycle and are the reactants for this process.

false

Oxidation is the gain of electrons.

false

The majority of ATP produced during acetyl-CoA synthesis is the result of substrate-level phosphorylation.

false

When glucose is broken down in a cell, all of the energy it stores is released simultaneously, not in a stepwise process.

false

Which one of the following is a monosaccharide and not a disaccharide?

fructose

In cellular respiration, oxygen:

gains electrons and is an oxidizing agent.

In which of the following molecules are the electrons of the atoms shared in covalent bonds at the furthest distance from the nucleus?

glucose

Excess glucose is stored in large branched molecules of:

glycogen in animals.

______________ is found in animals, and possesses a large, central protein. ____________ is found in plants, and lacks a central protein.

glycogen, starch

Proteins can be broken down for energy. They are typically broken down into amino acids, which then enter cellular respiration via:

glycolysis or the citric acid cycle.

Fermentation takes place:

in the cytoplasm

Due to the pumping action of the electron transport chain, protons have a high concentration in the _____ and a low concentration in the _____.

intermembrane space; mitochondrial matrix

Acetyl-CoA synthesis is an important step in cellular respiration because:

it links glycolysis with aerobic respiration.

During the citric acid cycle, the production of CO2 is a(n) _____ reaction coupled to the production of ____________.

oxidation; NADH

The electron transport chain is part of

oxidative phosphorylation.

During acetyl-CoA synthesis, pyruvate is:

oxidized

In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water.

oxidized; reduced

During fermentation, pyruvate is:

reduced

The _____ forms of the electron carriers NAD+/NADH and FADH/FADH2 have high potential energy.

reduced

The coronary arteries supply blood to the heart muscles. Which of the following events would occur in heart tissue following a heart attack due to a block in the coronary arteries?

-There would be an accumulation of lactic acid in the tissue due to glycolysis and fermentation. -There would be a decrease in the production of ATP. -There would be a stimulation of phosphofructokinase, an intermediary enzyme of glycolysis.

Which of the following is a net product of the citric acid cycle for each molecule of pyruvate generated in glycolysis

1 ATP 3 NADH 1 FADHv2

Which of the following correctly lists the approximate number of ATP produced by (i) beta-oxidation of a 16-carbon fatty acid, (ii) glycolysis and fermentation of a single glucose, and (iii) aerobic respiration of a single glucose, in that order?

106, 2, 32

A single molecule of glucose requires _____ "turns" through the citric acid cycle for its chemical energy to be completely harvested.

2

How many reactions in glycolysis directly generate ATP

2

Which regulatory mechanism is activated when the overall energy availability of a cell is high

ATP inhibits phosphofructokinase 1.

Which regulatory mechanism is important in keeping glycolysis and the citric acid cycle in relative balance to each other

Citrate inhibits phosphofructokinase 1

Which one of the following complexes does not actively move protons from the mitochondrial matrix to the intermembrane space?

Complex II

The inputs to glycolysis do not include:

NADH

ATP is not generated directly in the citric acid cycle; instead, an intermediate is first generated by substrate-level phosphorylation. The intermediate is:

GTP.

Imagine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation?

Glucose could move out of the cell, slowing cellular respiration.

You may be familiar with the story of Philippides, the famous Grecian who ran the first marathon and then died after completing his run. Based on what you know of aerobic respiration and fermentation, why might Philippides have died?

His muscles may have produced toxic levels of lactic acid, causing his blood to become more acidic

What happens to pyruvate during the process of fermentation?

It is reduced to ethanol.

If oxygen is unavailable, predict what happens to the citric acid cycle.

It stops because the supplies of NAD+ and FAD become depleted.

Glycolysis is:

anaerobic.

Imagine that you notice rust has formed on the frame of your bicycle. How would this have happened?

The iron in your bicycle frame was oxidized and lost electrons.

Which of the following statements is true regarding the equation C6H12O6 + 6O2 →6CO2+ 6H2O + energy?

The oxygen atoms in both CO2 and H2O are electronegative, and glucose could be considered a reducing agent.

Which of the following statements is true regarding triacylglycerols?

Triacylglycerols can be used to generate acetyl-CoA.

Energy released by transferring electrons along the electron transport chain is stored as potential energy in the form of:

a proton gradient.

Certain complexes of the mitochondrial electron transport chain pump protons. Which of the following best describes the movement of protons in this situation?

across the inner mitochondrial membrane, from the matrix to the intermembrane space

In which form are electrons transferred during typical redox reactions such as the oxidation of glucose?

as hydrogen atoms

Lactic acid fermentation occurs in:

bacteria and animals

The breakdown of fatty acids takes place via a process called:

beta-oxidation

How did the earliest organisms on Earth most likely produce ATP?

by glycolysis

Cellular respiration is a series of _____ reactions.

catabolic

The second phase of glycolysis:

cleaves a phosphorylated sugar molecule and rearranges the products.

Phosphorylating glucose during phase 1 of glycolysis:

destabilizes the glucose molecule so that it can be broken down in stage 2.

At what phase of glycolysis is NADH formed?

during Phase 3, when glyceraldehyde 3-phosphate is phosphorylated

In the first three stages of cellular respiration, the chemical energy in glucose is transferred to:

electron carriers and ATP.

The proteins of the electron transport chain are:

embedded in the inner mitochondrial membrane.

The first phase of glycolysis requires the input of two ATP molecules. It is therefore:

endergonic

Which of the following statements is true regarding a reducing agent?

it loses electrons

In human cells such as muscle tissue, the product of anaerobic respiration is

lactic acid

Starting with glycolysis, lactic acid and ethanol fermentation generate only two ATP per glucose molecule. The remaining chemical energy from the glucose is found primarily in:

lactic acid and ethanol

During acetyl-CoA synthesis, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:

less energetic than the acetyl group.

Glycogen stored in muscles can be "mobilized" to supply metabolic energy by hydrolyzing individual glucose subunits from the polymer. What other organ has a major function of storing glycogen?

liver

In eukaryotes, acetyl-CoA synthesis takes place in the:

mitochondrial matrix.

In what organelle is acetyl-CoA synthesis carried out in a cell?

mitochondrion

Which of the following is not an end product for an acetyl group that enters the citric acid cycle?

oxaloacetate

The citric acid cycle begins when acetyl-CoA combines with ____________ to form ____________.

oxaloacetate; citrate

When an electron is transferred from NADH to CoQ, NADH is __________________ and CoQ is _____________________.

oxidized; reduced

The final electron acceptor of the electron transport chain is:

oxygen

Which of the following does not occur during the third phase of glycolysis?

oxygen consumption

Fermentation occurs in:

some aerobic organisms, such as yeast, even in the presence of oxygen.

In glycolysis, ATP is synthesized via:

substrate level phosphorylation.

Which of the following processes produces the highest number of electron carriers and thus the greatest amount of ATP via oxidative phosphorylation?

the citric acid cycle

The pyruvate dehydrogenase complex plays a role in which of the following processes?

the formation of CO2, NADH, pyruvate, and acetyl-CoA

Which is the only reaction in the citric acid cycle that produces ATP by substrate-level phosphorylation?

the formation of succinate

Imagine that you exhale after a deep breath. What are you not exhaling?

waste products of glycolysis

We can tell from their structure that fatty acids are a good source of energy because of:

the large number of carbon-carbon and carbon-hydrogen bonds they contain.

In eukaryotic cells, the oxidation of pyruvate occurs in:

the matrix of the mitochondria

The chemical bonds of carbohydrates and lipids have high potential energy because:

their electrons are far away from the nuclei of the atoms.

Which of the following is a mobile electron carrier in the electron-transport chain?

ubiquinone cytochrome c

The phosphorylation of glucose during glycolysis serves to:

trap imported glucose inside the cell and destabilize the molecule, making it easier to cleave

Although cellular respiration is typically thought of as an aerobic process, glycolysis itself is actually anaerobic.

true

Although glycolysis produces four molecules of ATP via substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is due to the fact that glycolysis is—at first—endergonic.

true

The ATP produced during glycolysis is the result of substrate-level phosphorylation

true

True or False: fats are not an animal's primary source of energy because some tissue types like brain tissue use glucose exclusively.

true

Which of the following is not one of the net final products of glycolysis?

two molecules of acetyl-CoA

At the end of glycolysis, the carbon molecules originally found in the starting glucose molecule are in the form of:

two pyruvate molecules