Chapter 7 Biology

The coronary arteries supply oxygenated blood to heart muscle. Following a heart attack, which of the events would occur in heart tissue due to a block in the coronary arteries? Select all that apply.

Phosphofructokinase, an intermediary enzyme of glycolysis, would be activated. The production of ATP would decrease. Lactic acid would accumulate in the tissue due to glycolysis and fermentation.

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

a proton gradient.

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

endergonic.

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

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 eukaryotes, pyruvate oxidation takes place in the:

mitochondrial matrix.

The citric acid cycle takes place in the:

mitochondrial matrix.

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

mitochondrion

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

oxygen.

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

payoff phase

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

the citric acid cycle

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.

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

two pyruvate molecules.

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

In eukaryotic cells, glycolysis occurs in:

the cytoplasm.

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

traps glucose inside the cell

Tracing the metabolism of one glucose molecule, how many carbon atoms are available for further oxidation at the completion of the pyruvate oxidation stage?

4

During the citric acid cycle:

ATP is synthesized by substrate-level phosphorylation

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

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

NADH and CO2.

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.

Which statement is true regarding Earth's earliest organisms?

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

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

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

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 cellular respiration, oxygen:

gains electrons and is reduced.

Excess glucose is stored in large branched molecules of:

glycogen in animals.

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

glycogen; starch

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.

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

by glycolysis

Cellular respiration is a series of _____ reactions.

catabolic

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

beta-oxidation.

During what phase of glycolysis is NADH formed?

during phase 3, when glyceraldehyde 3-phosphate is phosphorylated

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

0

Which choice correctly lists the approximate number of ATP produced by (1) metabolism of a 16-carbon fatty acid, (2) fermentation of a single glucose, and (3) aerobic respiration of a single glucose, in that order? For this calculation, you will need to know that each 2-carbon unit cleaved from the fatty acid yields one NADH and one FADH2, and the 2-carbon unit is added to coenzyme A to become acetyl-CoA, which is further metabolized by the citric acid cycle.

108, 2, 32

Which of the following is a net product of glycolysis?

2 pyruvate

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

6

The diagram shown represents the four stages of aerobic cellular respiration as four simple boxes. Many of the "inputs" and "outputs" are shown as arrows. Open arrows represent "energy management molecules" (ATP and electron carriers), and closed arrows represent other inputs and outputs, such as substrates and products. Use this diagram to answer the question.

A

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

All of these choices are correct.

Which of these reactions summarizes the overall reactions of cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

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

The ethanol resulting from fermentation of glucose only accounts for four of the six starting carbon atoms. In which of the following are the other two carbon atoms found?

CO2

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

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

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

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.

During the citric acid cycle, which is shown, what happens to the coenzyme A that is part of acetyl-CoA?

It is recycled for use in other reactions.

Glycolysis is:

anaerobic.

Lactic acid fermentation occurs in:

bacteria and animals.

During glycolysis, pyruvate oxidation, and the citric acid cycle, the chemical energy in glucose is transferred to:

electron carriers and ATP.

Most of the proteins of the electron transport chain are:

embedded in the inner mitochondrial membrane.

Oxidation is the gain of electrons.

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

Which of the following is most likely to have been the first metabolic pathway or structure to evolve?

fermentation

Pyruvate oxidation is an important stage in cellular respiration because:

it links glycolysis with the citric acid cycle.

During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:

less energetic than the acetyl group.

Acetate is the starting point for synthesis of a cell's:

lipids

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

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

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

oxidized; reduced

When you exhale, there is more CO2 than was present in the air that you inhaled. This CO2 comes from reactions in:

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

In glycolysis, ATP is synthesized by:

substrate-level phosphorylation

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