Chapter 7

In eukaryotes, pyruvate oxidation takes place in the:

mitochondrial matrix.

The citric acid cycle takes place in the:

mitochondrial matrix.

Which stages of cellular respiration use O2 as an input?

oxidative phosphorylation

The mitochondrial electron transport chain is part of:

oxidative phosphorylation.

A molecule that is _____ loses electrons, and a molecule that is _____ gains electrons.

oxidized; reduced

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

oxidized; reduced

The final (terminal) electron acceptor of the electron transport chain is:

oxygen.

A simplified overall equation for respiration is as follows: C6H12O6 + 6O2 →6CO2+ 6H2O + energy In this reaction, we can say that _____ is reduced and _____ is oxidized.

oxygen; glucose

During which phase(s) of glycolysis do we observe pyruvate production, ATP synthesis, and reduction of NAD+?

payoff phase

Which stage of cellular respiration occurs following production of pyruvate? Please choose the correct answer from the following choices, and then select the submit answer button. pyruvate oxidation

pyruvate oxidation

Which stages of cellular respiration produce CO2 as a waste product?

pyruvate oxidation and the citric acid cycle

Acetyl-CoA synthesis occurs during:

pyruvate oxidation.

In pyruvate oxidation, the electron donor is _____ and the electron acceptor is _____.

pyruvate; NAD+

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

reduced

During lactic acid fermentation, pyruvate is:

reduced.

Which of the following summarizes the net final products of glycolysis?

two molecules of pyruvate, two molecules of ATP, and two molecules of NADH

Malate is both the starting and ending product of the citric acid cycle.

False

Pyruvate oxidation produces a large amount of ATP through substrate-level phosphorylation.

False

The glycolysis stage is responsible for producing most of the ATP during cellular respiration.

False

The majority of cells within the human body have a very high baseline amount of ATP, so cells are always prepared for any long-term activity.

False

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

NADH and CO2.

The immediate source of electrons for the electron transport chain is:

NADH and FADH2.

In the cleavage phase of glycolysis:

a phosphorylated sugar molecule is broken apart and the products rearranged.

Most of the proteins of the electron transport chain are:

embedded in the inner mitochondrial membrane.

Where does the F1 subunit of ATP synthase get its energy to catalyze the synthesis of ATP?

from rotational energy provided by the flow of protons through the channel in the Fo subunit

In which organisms would you expect ethanol fermentation to occur?

fungi and plants

In cellular respiration, oxygen:

gains electrons and is reduced.

Excess glucose is stored in large branched molecules of:

glycogen in animals.

The storage carbohydrate in animals is ___________ and in plants is __________.

glycogen; starch

When a substance in a reaction is oxidized, it:

loses electrons.

At the end of glycolysis, the carbon originally found in the starting glucose molecule is now present in:

two pyruvate molecules.

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

a proton gradient.

Which of the following are inputs, but not outputs, of glycolysis?

glucose

Which of the following is a net product of glycolysis?

2 pyruvate

Cellular respiration is a series of _____ reactions.

catabolic

Tracing the metabolism of one glucose molecule, how many carbon atoms are fully oxidized to CO2 at the completion of glycolysis?

0

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

2

Starting from glucose, lactic acid fermentation results in _____ molecules of lactic acid, each with _____ carbons, whereas ethanol fermentation results in _____ molecules of ethanol, each with _____ carbons.

2; 3; 2; 2

Tracing the metabolism of one glucose molecule, how many carbon atoms are fully oxidized to CO2 at the completion of aerobic respiration?

6

Which best describes energy captured in ATP during aerobic cellular respiration?

A small amount of energy is captured in ATP by substrate-level phosphorylation; most is captured in ATP by oxidative phosphorylation.

During the citric acid cycle:

ATP is synthesized by substrate-level phosphorylation.

Each molecule of acetyl-CoA that enters the citric acid cycle carries two of the carbon atoms from the original starting glucose molecule. These carbon atoms will ultimately leave the citric acid cycle as carbon atoms in which of the following?

CO2

We consume a variety of carbohydrates that are digested into a variety of different monosaccharides. How do these different sugars enter glycolysis?

Different sugars can be modified to form different intermediates of glycolysis.

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

False

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

GTP.

What happens when glucose is phosphorylated during phase 1 of glycolysis?

Glucose is destabilized so that it can be broken apart in phase 2.

Which of the following is one explanation for why glycolysis is believed to have arisen very early in the evolution of life?

It does not require oxygen.

One of the enzymatic results of the pyruvate oxidation stage of cellular respiration is the reduction of _____ to _____.

NAD+; NADH

What product of the pyruvate oxidation stage of cellular respiration will have the two electrons that are lost from pyruvate?

NADH

Which of the following is an electron carrier in its reduced form?

NADH

Which statement is true regarding pyruvate oxidation?

Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis.

Which statement is true regarding triacylglycerols?

The fatty acids from triacylglycerols are broken down to generate acetyl-CoA.

Which statement is true regarding Earth's earliest organisms?

These organisms likely carried out fermentation and may have had rudimentary proton pumps.

Conditions that reduce the strength of the proton gradient across the inner mitochondrial membrane slow the production of ATP by ATP synthase.

True

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

True

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

True

Glycolysis is:

anaerobic.

Lactic acid fermentation occurs in:

bacteria and animals.

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

beta-oxidation.

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

by glycolysis

During what phase of glycolysis is NADH formed?

during phase 3, when glyceraldehyde 3-phosphate is phosphorylated

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

endergonic.

In a plant cell, the oxidative phosphorylation stage of cellular respiration is carried out in the cytoplasm.

false

Oxidation is the gain of electrons.

false

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

glycolysis or the citric acid cycle.

Pyruvate oxidation is an important stage in cellular respiration because:

it links glycolysis with the citric acid cycle.

On completion of either ethanol or lactic acid fermentation, the yield is only two ATP molecules per glucose molecule. The remaining chemical energy from the glucose is found primarily in:

lactic acid and ethanol.

Red blood cells in the human bloodstream do not have mitochondria. What metabolic process would you predict these cells use to provide cellular energy/ATP?

lactic acid fermentation

In glycolysis, ATP is synthesized by:

substrate-level phosphorylation.

Which process produces the highest number of reduced electron carriers and thus the greatest potential for generating ATP?

the citric acid cycle

In eukaryotic cells, glycolysis occurs in:

the cytoplasm.

During the pyruvate oxidation stage of cellular respiration, which of the following occurs?

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

In addition to destabilizing glucose for subsequent breakdown, what else does phosphorylation of glucose do?

traps glucose inside the cell

Both NAD+ and molecular oxygen serve as electron acceptors in cellular respiration.

true

Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is because:

two molecules are used in the initial stage.

Which of the following is a product (as opposed to a substrate) of at least one of the processes of cellular respiration?

water

What is the fully oxidized product that results from the pyruvate oxidation stage of cellular respiration?

CO2

The glycolysis stage is responsible for producing most of the ATP during cellular respiration.

false

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

many of these bonds are C—C and C—H bonds, in which electrons are shared equally between atoms.

In what organelle is pyruvate oxidation carried out in a cell?

mitochondrion

The loss of electrons is referred to as:

oxidation

During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____.

oxidation; NADH

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

oxidized; reduced

Glucose is stored in plants as _____ and in animals as _____.

starch; glycogen