Chapter 7

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

two pyruvate molecules.

Which of the following is required for the preparatory phase of glycolysis and then produced during the payoff phase?

ATP

During the citric acid cycle:

ATP is synthesized by substrate level phosphorylation.

Excess glucose is stored in large branched molecules of:

glycogen in animals

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

6

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

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

The outer surface of the Fo subunit of ATP synthase must be _____ to be embedded in the membrane.

Hydrophobic

Glycolysis is:

anaerobic

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

lipids

In the absence of oxygen, fermentation:

regenerates NAD+ from the reduction of pyruvate

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

0

Oxidative phosphorylation yields _____ ATP for each molecule of FADH2 that is oxidized, whereas it yields _____ ATP for each molecule of NADH.

1.5;2.5

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

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

2

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

2 ATP, 6 NADH, 4 CO2, and 2 FADH2.

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

CO2

Fermentation occurs only in anaerobic conditions.

False

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

False

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

False

Oxidation is the gain of electrons.

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

Recall that fatty acids (such as palmitic acid) can yield substantially more ATP when compared with a similar weight of glucose. Why doesn't aerobic respiration rely solely on fatty acids as energy sources, rather than glucose?

Fatty acids cannot be used by some vital tissues in the human body, such as the brain

In which organisms would you expect ethanol fermentation to occur?

Fungi and plants

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

Glucose

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

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

Which statement describes the proton gradient generated by the electron transport chain?

It is an electrochemical gradient.

When a substance in a reaction is oxidized, it:

Loses electrons

When oxygen is depleted, the citric acid cycle stops. Which of the answer choices would you need to add to the system to restore activity?

NAD+ and FAD

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

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

Payoff phase

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?

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

Acetyl-CoA synthesis occurs during:

Pyruvate oxidation

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

Pyruvate oxidation and the citric acid cycle

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

Reduced

In eukaryotic cells, glycolysis occurs in:

The cytoplasm

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.

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

True

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

True

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

Water

Glycolysis is a series of chemical reaction (end ergo is and exergonic) by which the cell can obtain ATP. NAD+ plays a crucial role in the reaction of glycolysis by:

accepting electrons during glycolysis, with the overall result that glucose is partially oxidized to pyruvate.

Why do we believe that glycolysis and fermentation probably evolved very early in the history of life in an ancestor to essentially all life on Earth?

because these metabolic processes are found in nearly all organisms

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

by glycolysis

Cellular respiration is a series of _____ reactions.

catabolic

A research group has discovered an organism with cells that contain a previously undescribed organelle. Researchers perform some tests on the isolated organelle to see if it is involved in any major metabolic reactions. To do this, they incubate these organelles for a period of time and determine changes in the amount of various substances in the suspending solution.

citric acid cycle

During what phase of glycolysis is NADH formed?

during phase 3, when glyceraldehyde 3-phosphate is phosphorylated

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

electrons donated to NAD+ and FAD.

Most of 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

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

Pyruvate oxidation is an important stage in cellular respiration because:

it links glycolysis with the citric acid cycle.

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

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

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

oxidized; reduced

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

pyruvate; NAD+

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

traps glucose inside the cell

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.