Biology 1 Ch9 Mastering

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____. -all cells, but only in the presence of oxygen -all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors -only eukaryotic cells, in the presence of oxygen -only in mitochondria, using either oxygen or other electron acceptors

-all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? 2% 100% 0% 38%

100%

How many NADH are produced by glycolysis?

2

In glycolysis there is a net gain of _____ ATP. 4 1 2 5 3

2

Starting with one molecule of glucose, the energy-containing products of glycolysis are _____. -2 NAD+, 2 pyruvate, and 2 ATP -6 CO2, 2 pyruvate, and 2 ATP -2 FADH2, 2 pyruvate, and 4 ATP -2 NADH, 2 pyruvate, and 2 ATP

2 NADH, 2 pyruvate, and 2 ATP

What comes out of glycolysis?

2 pyruvate, 2 ATP, 2 NADH

Electron transport and chemiosmosis (oxidative phosphorylation) can yield around ___ molecules of ATP.

26

It takes 2 ATP to produce ___ ATP.

4

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) O2 is reduced and CO2 is oxidized.

A) C6H12O6 is oxidized and O2 is reduced.

Glucose is used to produce high-energy ___ in a cell.

ATP

In glycolysis, what starts the process of glucose oxidation? -ADP -hexokinase -NADPH -FADH2 -ATP

ATP

What is the role of chemiosmosis in ATP synthesis?

ATP synthase is the enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the free energy difference to phosphorylate adenosine diphosphate (ADP), making ATP.

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____.

ATP, CO2, and ethanol (ethyl alcohol)

What comes out of oxidative phosphorylation?

ATP, NAD+, FAD, water

What comes out of the Kreb's cycle?

ATP, NADH, FADH2, CO2

What goes into the Krebs Cycle?

Acetyl CoA

____ is a reactant in the citric acid cycle.

Acetyl CoA

The primary role of oxygen in cellular respiration is to _____. A) yield energy in the form of ATP as it is passed down the respiratory chain B) act as an acceptor for electrons and hydrogen, forming water C) combine with carbon, forming CO2 D) combine with lactate, forming pyruvate

B) act as an acceptor for electrons and hydrogen, forming water

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _____. A) active transport B) an endergonic reaction coupled to an exergonic reaction C) a reaction with a positive ΔG D) allosteric regulation

B) an endergonic reaction coupled to an exergonic reaction

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation.

C) It increases the surface for oxidative phosphorylation.

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____. A) formation of ATP B) reduction of NAD+ C) creation of a proton-motive force D) lowering of pH in the mitochondrial matrix

C) creation of a proton-motive force

In chemiosmosis, what is the most direct source of energy that is used to convert ADP + Pi to ATP? A) energy released as electrons flow through the electron transport system B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, down their electrochemical gradient D) No external source of energy is required because the reaction is exergonic.

C) energy released from movement of protons through ATP synthase, down their electrochemical gradient

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? A) mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix

C) mitochondrial intermembrane space

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? A) carbon dioxide (CO2) B) glucose (C6H12O6) C) molecular oxygen (O2) D) pyruvate (C3H3O3-)

C) molecular oxygen (O2)

equation for cellular respiration

C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy

What are the products of ethanol fermentation?

CO2, ethanol, and NAD+

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? 1.Carbon dioxide 2.NADH 3.ATP 4.Water

Carbon dioxide

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? A) 2 B) 4 C) 18-24 D) 30-32

D) 30-32

What does a reducing agent do?

Donates electrons and gets oxidized

Which stage of glucose metabolism produces the most ATP? 1.Glycolysis 2.Krebs cycle 3.Electron transport and chemiosmosis 4.Fermentation of pyruvate to lactate

Electron transport and chemiosmosis

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? FADH2 NADH ATP ADP + Pi

FADH2

Which of these is NOT a product of glycolysis? -NADH -ATP -pyruvate -FADH2

FADH2

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? -Krebs cycle -Glycolysis -Fermentation -Electron transport chain

Fermentation (Note: Fermentation is an alternate pathway used when oxygen levels are low.)

Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP? -ADP -Glucose -Carbon dioxide -Phosphate

Glucose

PRETEST In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced? -Oxygen is consumed, and glucose is produced. -Carbon dioxide is consumed, and water is produced. -Glucose is consumed, and carbon dioxide is produced. -ATP is consumed, and oxygen is produced. -Water is consumed, and ATP is produced.

Glucose is consumed, and carbon dioxide is produced.

Which step of the cellular respiration pathway can take place in the absence of oxygen? Electron transport chain Fermentation Krebs cycle Glycolysis

Glycolysis

___ takes place in the cytoplasm, whereas the ___ cycle and the ___ ___ chain, which generate the largest amounts of ATP during cellular respiration, take place in the mitochondria.

Glycolysis Krebs, electron transport

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

PRETEST 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 pyruvate.It is stored in the ATP that was formed by glycolysis & the citric acid cycle. -It was lost as heat. -It is stored in the CO2 & water molecules released by these processes. -It is stored in NADH & FADH2

It is stored in NADH and FADH2

PRETEST Which of the following describes the process of glycolysis? -It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. -It requires ATP and NADH. -Glycolysis occurs in the mitochondria. -It represents the first stage in the chemical oxidation of glucose by a cell. -Glycolysis produces 30 ATP from each molecule of glucose.

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

LEO the lion says GER

Losing Electrons Oxidizes (Reducing Agent) Gaining Electrons Reduction (Oxidizing Agent)

What is NADH in its oxidized form?

NAD+

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____. glucose pyruvate NADH acetyl-CoA

NADH

What is NAD+ reduced to?

NADH

Which electron carrier(s) function in the citric acid cycle? -NAD+ only -the electron transport chain -ADP and ATP -NADH and FADH2

NADH and FADH2

Which of the following statements about the electron transport chain is true? -Water is the last electron acceptor. -NADH and FADH2 donate their electrons to the chain. -Electrons gain energy as they move down the chain. -The electron transport chain is the first step in cellular respiration.

NADH and FADH2 donate their electrons to the chain.

What goes into oxidative phosphorylation?

NADH, O2

Electrons lose energy as they move down the chain, and this energy is used to create a proton gradient that drives the synthesis of ATP.

This is TRUE

Glycolysis can take place in the absence of oxygen; its product, pyruvate, enters the cellular respiration pathway or undergoes fermentation depending on the availability of oxygen.

This is TRUE

The three phosphate groups in an ATP molecule carry negative charges that strongly repel each other and give ATP a large amount of potential energy.

This is TRUE

The electrons obtained from the oxidation of glucose are temporarily stored in NADH and FADH2. The energy derived from the oxidation of NADH and FADH2 is used to drive the electron transport chain and chemiosmotic synthesis of ATP.

This is TRUE.

The potential energy in an ATP molecule is derived mainly from its three phosphate groups. True False

True

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria. 1. True 2. False

True

The oxygen consumed during cellular respiration is involved directly in which process or event? -the citric acid cycle -the oxidation of pyruvate to acetyl CoA -glycolysis -accepting electrons at the end of the electron transport chain

accepting electrons at the end of the electron transport chain

What does an oxidizing agent do?

accepts electrons and gets reduced

Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? citrate acetate oxaloacetate glyceraldehyde 3-phosphate

acetate

Which of these enters the citric acid cycle? NADH + H+ acetyl CoA pyruvate glucose G3P

acetyl CoA

Which of these is NOT a product of the citric acid cycle? NADH + H+ acetyl CoA FADH2 CO2 ATP

acetyl CoA

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. The three listed steps result in the formation of _____. -acetyl CoA, O2, and ATP -acetyl CoA, FADH2, and CO2 -acetyl CoA, NAD+, ATP, and CO2 -acetyl CoA, NADH, and CO2

acetyl CoA, NADH, and CO2

Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____.

all cells all the time

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of _____.

allosteric regulation

In respiration, beta oxidation involves the _____.

breakdown of fatty acids

Is cellular respiration catabolic or anabolic?

catabolic -because it breaks glucose into smaller molecules

Reduction-oxidation reactions

chemical reactions that involve electron transfer

Acetyl CoA enters the ... cycle

citric acid

FADH2 is a product of the ...

citric acid cycle

What goes into glycolysis?

glucose

Some ATP energy is used to start the process of ...

glucose oxidation

During aerobic respiration, electrons travel downhill in which sequence? glucose → ATP → electron transport chain NADH glucose → NADH → electron transport chain oxygen glucose → pyruvate → ATP → oxygen food → glycolysis → citric acid cycle → NADH → ATP Submit

glucose → NADH → electron transport chain oxygen

Catabolism of glucose begins with ___.

glycolysis

Which of the following normally occurs regardless of whether or not oxygen (O2) is present? -fermentation -citric acid cycle -glycolysis -oxidative phosphorylation (chemiosmosis)

glycolysis

Which of the following occurs in the cytosol of a eukaryotic cell? -oxidation of pyruvate to acetyl CoA -fermentation and chemiosmosis -citric acid cycle -glycolysis and fermentation

glycolysis and fermentation

Substrate-level phosphorylation occurs _____. -in the citric acid cycle -in both glycolysis and the citric acid cycle -during oxidative phosphorylation -in glycolysis

in both glycolysis and the citric acid cycle

An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____.

is a facultative anaerobe

In muscle cells, fermentation produces _____.

lactate and NAD+

What are the products of lactic acid fermentation?

lactate and NAD+

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____. -gains electrons and gains potential energy -gains electrons and loses potential energy -loses electrons and gains potential energy -loses electrons and loses potential energy

loses electrons and loses potential energy

Glycolysis is active when cellular energy levels are _____; the regulatory enzyme, phosphofructokinase, is _____ by ATP.

low; inhibited

Where are the proteins of the electron transport chain located? -mitochondrial matrix -mitochondrial intermembrane space -mitochondrial inner membrane -mitochondrial outer membrane

mitochondrial inner membrane

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? -oxidative phosphorylation and fermentation -oxidation of pyruvate to acetyl CoA and the citric acid cycle -fermentation and glycolysis -glycolysis and the oxidation of pyruvate to acetyl CoA

oxidation of pyruvate to acetyl CoA and the citric acid cycle

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

oxidize NADH to NAD+

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____. -oxidized -reduced -hydrolyzed -an oxidizing agent

oxidized

In fermentation _____ is reduced and _____ is oxidized.

pyruvate ... NADH (Note: The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.)

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes _____. -oxidized -dehydrogenated -reduced -redoxed

reduced

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____. -oxidized, and energy is consumed -reduced, and energy is released -reduced, and energy is consumed -oxidized, and energy is released

reduced, and energy is released

In glycolysis, ATP molecules are produced by _____. -substrate-level phosphorylation -cellular respiration -photophosphorylation -oxidative phosphorylation -photosynthesis

substrate-level phosphorylation

In the citric acid cycle, ATP molecules are produced by _____. -substrate-level phosphorylation -photophosphorylation -cellular respiration -photosynthesis -oxidative phosphorylation

substrate-level phosphorylation

Most of the CO2 from the catabolism of glucose is released during _____. -the citric acid cycle -electron transport -glycolysis -chemiosmosis

the citric acid cycle

Which of the following events takes place in the electron transport chain? -substrate-level phosphorylation -the breakdown of an acetyl group to carbon dioxide -the breakdown of glucose into two pyruvate molecules -the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

PRETEST Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? -breaking down ATP, so that ADP and P can be reused -producing complex molecules from chemical building blocks -transforming the energy in glucose and related molecules in a chemical form that cells can use for work -the breakdown of glucose to carbon dioxide and water -catabolism of sugars and related compounds

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

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

two ATP (Note: Four ATP are made, but two ATP are consumed to start the process of glycolysis.)

In glycolysis, for each molecule of glucose oxidized to pyruvate _____. -four molecules of ATP are used and two molecules of ATP are produced. -two molecules of ATP are used and two molecules of ATP are produced. -two molecules of ATP are used and six molecules of ATP are produced. -two molecules of ATP are used and four molecules of ATP are produced.

two molecules of ATP are used and four molecules of ATP are produced.