BIO1610 Chapter 7 Questions

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

payoff phase

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

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.

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

NADH and CO2.

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

false

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

false

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.

In eukaryotes, 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

Pyruvate oxidation is an important stage in cellular respiration because:

it links glycolysis with the citric acid cycle.

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

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

water

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

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

NADH

In the cleavage phase of glycolysis:

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

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 the absence of oxygen, fermentation:

regenerates NAD+ from the reduction of pyruvate.

Which of the following is a net product of glycolysis?

2 pyruvate

Glycolysis is:

anaerobic.

During lactic acid fermentation, pyruvate is:

reduced

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

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

2

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

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.

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

You may be familiar with the story of Philippides, the famous Greek runner 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.

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.

Which statement is true regarding pyruvate and glucose?

Pyruvate can be transported across both membranes of the mitochondrion to be further metabolized, but glucose cannot.

Which statement is true regarding pyruvate oxidation?

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

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

a proton gradient.

Beta-oxidation does not produce any ATP directly, but it does produce:

acetyl-CoA, NADH, and FADH2.

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

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

endergonic.

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.

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

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

less energetic than the acetyl group.

The loss of electrons is referred to as:

oxidation.

In eukaryotes, pyruvate oxidation takes place in the:

mitochondrial matrix.

The citric acid cycle is a cycle because the starting molecule, _____, is regenerated at the end.

oxaloacetate

Which stage of cellular respiration occurs following production of pyruvate?

pyruvate oxidation

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

pyruvate oxidation and the citric acid cycle

In glycolysis, ATP is synthesized by:

substrate-level phosphorylation.

Which of the following processes 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 CO2 the formation of acetyl-CoA the oxidation of pyruvate the formation of NADH

Of the 6 carbons in a starting molecule of glucose, at the completion of pyruvate oxidation, _____ carbons are fully oxidized to _____, while _____ carbons remain in _____.

two; CO2; four; acetyl groups

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

traps glucose inside the cell

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

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

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

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

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

two pyruvate molecules.