Campbell Chapter 9- Mastering Biology Questions

Which term describes the degree to which an element attracts electrons?

Electronegativity.

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

Anion and cation.

Which of the following statements is true of the bonds in a water molecule?

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.

Which of the following statements is not true of most cellular redox reactions?

A hydrogen atom is transferred to the atom that loses an electron.

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

Ionic.

Gaseous hydrogen burns in the presence of oxygen to form water:
2H2 + O2 → 2H2 O + energy
Which molecule is oxidized and what kind of bond is formed?

Hydrogen, polar.

Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration?

transforming the energy in glucose and related molecules in a chemical form that cells can use for work

In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?

Glucose is consumed, and carbon dioxide is produced.

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

pyruvate, ATP, and NADH NADH only ATP only O2 only CO2 only ATP and NADH only pyruvate and ATP only

Which of the following describes the process of glycolysis?

It represents the first stage in the chemical oxidation of glucose by a cell.

How many NADH are produced by glycolysis?

2

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation

Which of these is NOT a product of glycolysis?

FADH2

In glycolysis, what starts the process of glucose oxidation?

ATP

In glycolysis there is a net gain of _____ ATP.

2

In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction.

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?

It is stored in NADH and FADH2

Which of these enters the citric acid cycle?

acetyl CoA

In the citric acid cycle, ATP molecules are produced by _____.

substrate-level phosphorylation

Which of these is NOT a product of the citric acid cycle?

acetyl CoA

Which statement about the citric acid cycle is correct?

The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

The electrons stripped from glucose in cellular respiration end up in which compound?

water

In mitochondrial electron transport, what is the direct role of O2?

to function as the final electron acceptor in the electron transport chain

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

Both electron transport and ATP synthesis would stop.

Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

Which one of the following statements about the redox reactions of the electron transport chain is correct?

The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.

In muscle cells, fermentation produces _____.

lactate and NAD+

In fermentation _____ is reduced and _____ is oxidized.

pyruvate … NADH

In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?

two ATP

In most cells, not all of the carbon compounds that participate in glycolysis and the citric acid cycle are converted to carbon dioxide by cellular respiration. What happens to the carbon in these compounds that does not end up as CO2?

The carbon compounds are removed from these processes to serve as building blocks for other complex molecules.

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

H+ concentration across the membrane holding ATP synthase.

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

glycolysis

In mitochondria, exergonic redox reactions

provide the energy that establishes the proton gradient.

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

oxygen.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The pH of the matrix increases.

Most CO2 from catabolism is released during

the citric acid cycle.

Which of the following statements about the chemiosmotic synthesis of ATP is correct?

The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction

loses electrons and loses potential energy.

Which of the following statements describes the results of this reaction?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidized and O2 is reduced.

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes

oxidized.

Which of the following statements describes NAD+?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

Where does glycolysis take place in eukaryotic cells?

cytosol

The oxygen consumed during cellular respiration is involved directly in which process or event?

accepting electrons at the end of the electron transport chain

Why are carbohydrates and fats considered high energy foods?

They have a lot of electrons associated with hydrogen.

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

glycolysis

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

catabolic pathways

A molecule that is phosphorylated

has an increased chemical potential energy; it is primed to do cellular work.

Why is glycolysis described as having an investment phase and a payoff phase?

It uses stored ATP and then forms a net increase in ATP.

For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle (see the figure), what is the total number of NADH + FADH2 molecules produced?

12

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?

two

During cellular respiration, acetyl CoA accumulates in which location?

mitochondrial matrix

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

What is proton-motive force?

the force provided by a transmembrane hydrogen ion gradient

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration?

60-64

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?

oxidative phosphorylation (chemiosmosis)

Where is ATP synthase located in the mitochondrion?

inner membrane

One function of both alcohol fermentation and lactic acid fermentation is to

oxidize NADH to NAD+.

Which of the following normally occurs regardless of whether or not oxygen (O2) is present?

glycolysis

Which metabolic pathway is common to both cellular respiration and fermentation?

glycolysis

What is the purpose of beta oxidation in respiration?

breakdown of fatty acids