Biology Chapter 9- Homework

one of the atoms sharing electrons is more electronegative than the other.

A covalent bond is likely to be polar when

released as CO2 and H2O

A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?

Glucose

Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?

3 ATP, 6 CO2, 9 NADH, and 3 FADH2

Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?

the harnessing of energy from redox reactions to generate a proton gradient

Which of the following events takes place in the electron transport chain?

acetyl CoA

Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate?

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

Which of the following is the most important result of the process of cellular respiration in biological systems?

Its cells cannot transport pyruvate from the cytosol into the mitochondria.

A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?

fatty acids

Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?

pyruvate... NADH

In fermentation _____ is reduced and _____ is oxidized.

2 ATP

In glycolysis there is a net gain of _____ ATP.

the citric acid cycle.

Most CO2 from catabolism is released during

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

coupling of an endergonic reaction to an exergonic reaction

The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?

The reaction proceeds with a net release of free energy.

Which of the following is true for all exergonic reactions?

As you get older, your muscle mass decreases while the amount of collagen in your muscles increases.

Which of the following is true for most people?

glycolysis

Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability?

They contain many electrons associated with hydrogen atoms.

Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?

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

Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis?

oxidation of NADH to NAD+

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?

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

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

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

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

FADH2

Which of these is NOT a product of glycolysis?

acetyl CoA

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

Fermentation

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?

Glycolysis

Which step of the cellular respiration pathway can take place in the absence of oxygen?

Electronegativity

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

Anion and cation.

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

glucose

Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy?

Their maximum heart rate.

You are a personal trainer, working to help your clients achieve optimum fitness in the least amount of time. Which of the following is most important for you to discuss with them to determine how intensely they should be working out?

They are lethargic and readily tire from exercise.

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?

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

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

mitochondrial intermembrane space

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

2 NADH

How many NADH are produced by glycolysis?

it is stored in NADH and FADH2

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 happens to most of the energy that the cell obtains from the oxidation of glucose?

Less time for exercise is needed if you exercise at a vigorous intensity.

Recent research indicates which of the following?

Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.

Select the correct statement about cellular respiration.

correct statements -One of the substrates is a molecule derived from the breakdown of glucose. -An enzyme is required in order for the reaction to occur. -A bond must be broken between an organic molecule and phosphate before ATP can form. incorrect statements -The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP. -The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions.

Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis. The ATP that is generated in glycolysis is produced by substrate-level phosphorylation, a very different mechanism than the one used to produce ATP during oxidative phosphorylation. Phosphorylation reactions involve the addition of a phosphate group to another molecule.

100%

Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?

Catabolic processes will be activated to generate additional ATP.

A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?

Which of the following is the most correct interpretation of the figure?

ATP is a molecule that acts as an intermediary to store chemical energy for cellular work.

Structure A is _____.

ATP synthase

pyruvate, ATP, and NADH

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

30-32

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

8 kcal/mol

Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2?

In the sequential reactions of acetyl CoA formation and the citric acid cycle, pyruvate (the output from glycolysis) is completely oxidized, and the electrons produced from this oxidation are passed on to two types of electron acceptors.

As in glycolysis, the electrons removed from carbon-containing intermediates during acetyl CoA formation and the citric acid cycle are passed to the electron carrier NAD+, reducing it to NADH. The citric acid cycle also uses a second electron carrier, FAD (flavin adenine dinucleotide), the oxidized form, and FADH2, the reduced form.

There will be no real change in the exercise habits of adults in the coming years.

Assuming the U.S. is similar to the U.K., which of the following will occur?

directly entering the citric acid cycle

Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?

NADH and FADH2 ... intermembrane space

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

all of the electron transport system and ATP synthase

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?

The inside of the vesicles will become acidic.

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?

6

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

2

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

Hydrogen, polar

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?

2 NADH, 2 pyruvate, and 2 ATP

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?

provide the energy that establishes the proton gradient.

In mitochondria, exergonic redox reactions...

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

In mitochondrial electron transport, what is the direct role of O2O2?

allosteric regulation

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

The individual's ATP production will not change significantly.

How will a healthy individual's ATP production change during an eight-hour fast?

Both electron transport and ATPATP synthesis would stop.

How would anaerobic conditions (when no O2O2 is present) affect the rate of electron transport and ATPATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATPATP synthesis in glycolysis or the citric acid cycle.)

12.5

If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?

FMN prosthetic groups would remain reduced and NADH would have nowhere to donate electrons.

If a mitochondrion ran out of molecular oxygen (O2), predict which of the following situations would occur in its electron transport chain.

1/3

If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?

inner membrane

If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?

The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain?

oxidative phosphorylation

In cellular respiration, most ATP molecules are produced by _____.

from movement of protons through ATP synthase, down their electrochemical gradient

In chemiosmosis, the most direct source of energy used to convert ADP + Pi to ATP is energy released ________.

substrate-level phosphorylation

In glycolysis, ATP molecules are produced by _____.

1. When a compound donates (loses) electrons, that compound becomes oxidized. Such a compound is often referred to as an electron donor. 2. When a compound accepts (gains) electrons, that compound becomes reduced. Such a compound is often referred to as an electron acceptor. 3. In glycolysis, the carbon-containing compound that functions as the electron donor is glucose. 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called pyruvate. 5. NAD+ is the compound that functions as the electron acceptor in glycolysis. 6. The reduced form of the electron acceptor in glycolysis is NADH.

In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox, reactions.

ATP

In glycolysis, what starts the process of glucose oxidation?

oxidative phosphorylation

In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below?

they are removed from these processes to serve as building blocks for other complex molecules

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?

lactate and NAD+

In muscle cells, fermentation produces _____.

two ATP

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

ATP, CO2, and ethanol

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?

substrate-level phosphorylation

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

pyruvate

In the following reaction which molecule functions as the oxidizing agent? Pyruvate + NADH + H+ →→ Lactate + NAD+

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.

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.

glucose is consumed and carbon dioxide is produced

In the process of cellular respiration, what is consumed and what is produced?

in both glycolysis and the citric acid cycle

In which reactions of cellular respiration does substrate-level phosphorylation occur?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

Inhibition of which of the following metabolic pathways would result in decreased rates of CO2 production?

pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space

Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria?

Carbon dioxide

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?

Fewer protons are pumped across the inner mitochondrial membrane when FADH2FADH2 is the electron donor than when NADHNADH is the electron donor.

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.

During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.

New biosensors, applied like a temporary tattoo to the skin, can alert endurance athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate present in sweat during strenuous exercise. Which of the statements below best explains the use of lactate as an indicator of exercise capacity?

FADH2 -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2

Of the following lists of electron transport compounds, which one lists them in order from the one containing electrons with the highest free energy to the one containing electrons with the lowest free energy? Note that not all electron transport compounds in the electron transport chain are listed.

In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.

Part B - Anaerobic conditions and acetyl CoA formation Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation?

ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.

Part C - Cellular respiration and a cell's demand for ATP The rate of cellular respiration is regulated by its major product, ATP, via feedback inhibition. As the diagram shows, high levels of ATP inhibit phosphofructokinase (PFK), an early enzyme in glycolysis. As a result, the rate of cellular respiration, and thus ATP production, decreases. Feedback inhibition enables cells to adjust their rate of cellular respiration to match their demand for ATP. Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?

Glucose utilization would increase a lot.

Part D - Fermentation - ATP production in the absence of oxygen Part complete Under anaerobic conditions (a lack of oxygen), glycolysis continues in most cells despite the fact that oxidative phosphorylation stops, and its production of NAD+ (which is needed as an input to glycolysis) also stops. The diagram illustrates the process of fermentation, which is used by many cells in the absence of oxygen. In fermentation, the NADH produced by glycolysis is used to reduce the pyruvate produced by glycolysis to either lactate or ethanol. Fermentation results in a net production of 2 ATP per glucose molecule. During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. What would happen to the cell's rate of glucose utilization?

4

The citric acid cycle. For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?

Oxaloacetate will accumulate and citrate will decrease.

The citric acid cycle. If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?

water

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

ATP and citrate

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?

oxygen

The final electron acceptor of cellular respiration is _____.

O2

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

Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?

Citric Acid Cycle (Krebs Cycle)

This diagram of the citric acid cycle shows the carbon skeletons of each intermediate. The net result of this complex series of reactions is the complete oxidation of the two carbon atoms in the acetyl group of acetyl CoA to two molecules of CO2.

TRUE

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

TRUE

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

a monosaccharide and a fatty acid

Two molecules with the chemical formulas C6H12O6 and C6H12O2 are probably

in all cells, with or without light

Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?

H+ concentration gradient across the membrane holding ATP synthase.

Water at the top of a dam has potential energy; water falling through a dam has kinetic energy. The moving water performs work by moving the blades of turbines in the dam to generate electricity.

NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2

What is the correct order of electron transport compounds from best electron donor to best electron acceptor?

Pyruvate

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

ionic bond

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

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

What types of cells carry out ATP synthesis by chemiosmosis?

the electron transport chain

When a cell is deprived of oxygen, which of the following processes will be inhibited first?

oxidized

When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.

reduced, and energy is released

When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.

The pH of the matrix increases

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

glycolysis

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

The rates of ATP production and carbon dioxide production would both increase.

Which of the following is the most likely effect on the rates of ATP and CO2 production if yeast cells growing in minimal medium lacking glucose are provided with supplemental acetyl-CoA?

Valence electrons have a higher energy level than those in other filled shells.

Which of the following is true of the energy levels of electrons in shells?

glycolysis and fermentation

Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?

FADH2

Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?

oxidative phosphorylation

Which of the following processes is driven by chemiosmosis?

the citric acid cycle

Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?

glucose → NADH → electron transport chain → oxygen

Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration?

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

Which of the following statements about the chemiosmotic synthesis of ATP 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.

Which of the following statements about the citric acid cycle is correct?

NADH and FADH2 donate their electrons to the chain.

Which of the following statements about the electron transport chain is true?

The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?

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

Which of the following statements best describes a characteristic of NAD+?

It loses a hydrogen atom and loses potential energy.

Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction?

It consists of a series of redox reactions.

Which of the following statements best describes the electron transport chain?

It serves as the final acceptor for electrons from the electron transport chain.

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

NAD+ becomes reduced.

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?

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

Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved?

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

Which of the following statements describing the process of glycolysis is correct?

an agent that closely mimics the structure of glucose but is not metabolized

Which of the following types of metabolic poison would most directly interfere with glycolysis?

C6H12O6 is oxidized and O2 is reduced.

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

acetyl CoA

Which of these enters the citric acid cycle?

Electron transport and chemiosmosis

Which stage of glucose metabolism produces the most ATP?

yoga

Your 60-year-old aunt was recently diagnosed with sarcopenia. Which of the following activities will likely help her the most?