Chapter 9 Questions
How would anaerobic conditions affect the rate of electron transport and ATP production during oxidative phosphorylation?
Both electron transport and ATP synthesis would stop. Submit
Select the correct statement about cellular respiration.
Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
Stage of cellular respiration: Glycolysis Location:
Cytosol
Substrate-Level Phosphorylation in Glycolysis: T or F: The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions.
False
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
Stage of cellular respiration: Acetyl CoA formation Location:
Mitochondrial Matrix
Net outputs of Oxidative Phosphorylation
NAD+, ATP, water
Net outputs of Citric Acid Cycle
NADH, CO2, ATP, Coenzyme A
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.
Why are carbohydrates and fats frequently considered high-energy foods?
They contain many electrons associated with hydrogen atoms.
What kinds of cells carry out ATP synthesis by chemiosmosis?
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
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 term describes the degree to which an element attracts electrons?
electronegativity
Which of the following statements about the electron transport chain is true?
it consists of a series of redox reactions
The coupled stages of cellular respiration (inner square)
(From outer square going into inner square) Glycolysis -> Pyruvate -> (inner square) Acetyl CoA formation & Citric Acid Cycle -> NADH -> Oxidative phosphorylation -> NAD+ -> Back to acetyl CoA
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA?
1/3
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
100%
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
12.5
How many NADH are produced by glycolysis?
2
In glycolysis there is a net gain of _____ ATP.
2
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
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.
In glycolysis, what starts the process of glucose oxidation?
ATP
how this increased demand would lead to an increased rate of ATP production?
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production
Which of these enters the citric acid cycle?
Acetyl CoA
Net inputs of Citric Acid cycle
Acetyl CoA, NAD+, ADP
Carbon atoms in acetyl CoA formation and the citric acid cycle
Acetyl Coa: 2C Cytrate: 6C Isocitrate: 6C A-Ketoglutarate: 5C Succinyl CoA: 4C Succinate: 4C Fumarate: 4C Malate: 4C Oxaloacetate: 4C
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
CO2
Not inputs or outputs of Oxidative phosphorylation
CO2, glucose, coenzyme A, acetyl CoA, pyruvate
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?
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
Which stage of glucose metabolism produces the most ATP?
Electron transport and chemiosmosis
Which of these is NOT a product of glycolysis?
FADH2
Substrate-Level Phosphorylation in Glycolysis: T or F: The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP.
False
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
Fermentation
Why is there more ATP 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.
In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?
Glucose is consumed, and carbon dioxide is produced.
What would happen to the cell's rate of glucose utilization , Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions?
Glucose utilization would increase a lot
Not inputs or outputs of Citric Acid cycle
Glucose, O2, pyruvate
Which step of the cellular respiration pathway can take place in the absence of oxygen?
Glycolysis
The coupled stages of cellular respiration (outer square)
Glycolysis -> NADH -> Oxidative phosphorylation -> NAD+ -> Back to Glycolysis
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration across the membrane holding ATP synthase.
A young dog has never had much energy. He is brought to a veterinarian for help, and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition?
His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops.
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
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
It increases the surface for oxidative phosphorylation.
Why are the last two carbons in acetate 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.
Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?
It loses electrons and loses potential energy.
Which of the following describes the process of glycolysis?
It represents the first stage in the chemical oxidation of glucose by a cell.
Products of pyruvate metabolism
Lactate: Fermentation of human muscle Ethanol: Fermentation in yeast and bacteria Acetyl Coa: Aerobic oxidation
Stage of cellular respiration: Citric acid cycle Location:
Mitochondrial Matrix
_______ is the compound that functions as the electron acceptor in glycolysis
NAD+
Which of the following statements about NAD+ is true?
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
The reduced form of the electron acceptor in glycolysis is ______
NADH
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+
NADH
Which of the following statements about the electron transport chain is true? 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. Water is the last electron acceptor.
NADH AND FADH2 donate their electrons to the chain
Net Outputs of CoA
NADH, Acetyl CoA, CO2
The effect of gramicidin on Oxidative phosphorylation- Increases:
Nothing
Not Inputs or Outputs of CoA
O2, ADP, Glucose, ATP
Net inputs of oxidative phosphorylation
O2, ADP, NADH
Not inputs or outputs of glycolysis
O2, CO2, Coenzyme A, Acetyl CoA
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
Oxaloacetate will accumulate and citric acid will decrease.
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.
The effect of gramicidin on Oxidative phosphorylation- Remains the Same:
Proton pumping rate Electron Transport rate Rate of oxygen uptake
Net redox reaction in acetyl CoA formation and the citric acid cycle
Pyruvate is oxidized to CO2 NAD+ is reduced to NADH FAD is reduced to FADH2
Net outputs of glycolysis
Pyruvate, NADH, ATP
Net Inputs of CoA
Pyruvate, coenzyme A, NAD+
The effect of gramicidin on Oxidative phosphorylation- Decreases:
Rate of ATP synthesis Size of proton gradient
Reactants and products of lactic acid fermentation
Reactants: Pyruvate and NADH Products: Lactate and NAD+
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?
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 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.
Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?
The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements about these inside-out membrane vesicles is true?
The inside of the vesicles will become acidic when NADH is added.
Substrate-Level Phosphorylation in Glycolysis: T or F: A bond must be broken between an organic molecule and phosphate before ATP can form
True
Substrate-Level Phosphorylation in Glycolysis: T or F: An enzyme is required in order for the reaction to occur
True
Substrate-Level Phosphorylation in Glycolysis: T or F: One of the substrates is a molecule derived from the breakdown of glucose
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.
True
Which of these is NOT a product of the citric acid cycle?
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. Which of the following sets of products result from these reactions?
acetyl CoA, NADH, CO2
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
Which kind of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
In the citric acid cycle, ATP molecules are produced by _____.
cellular respiration
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 which of the following processes?
coupling of an endergonic reaction to an exergonic reaction
In chemiosmosis, what is the most direct source of energy that is used to convert ADP +Pi to ATP?
energy released from movement of protons through ATP synthase, down their electrochemical gradient
In glycolysis, the carbon-containing compound that functions as the electron donor is ______
glucose
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?
glucose
Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
glucose
Net inputs of glycolysis
glucose, NAD+, ADP
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Even though plants cells carry out photosynthesis, they still use their mitochondria for oxidation of pyruvate. Under what conditions will plant cell mitochondria be active in this process?
in all cells, with or without light
Stage of cellular respiration: Oxidative phosphorylation Location:
inner mitochondrial membrane
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
ionic
In muscle cells, fermentation produces _____.
lactate and NAD+
Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH to NAD+
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
When a compound donates (loses) electrons, that compound becomes _______. Such a compound is often referred to as an electron donor.
oxidized
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
oxygen
Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called ________
pyruvate
Among the products of glycolysis, what compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
In fermentation _____ is reduced and _____ is oxidized.
pyruvate; NADH
When a compound accepts (gains) electrons, that compound becomes ________. Such a compound is often referred to as an electron acceptor.
reduced
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released?
the citric acid cycle
Most CO2 from catabolism is released during
the citric acid cycle
What happens when electrons are passed from one atom to a more electronegative atom?
the more electronegative atom is reduced, and energy is released
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain
START OF REVIEW!!!!!!!! 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 glycolysis, for each molecule of glucose oxidized to pyruvate, ________.
two molecules of ATP are used, and four molecules of ATP are produced
The electrons stripped from glucose in cellular respiration end up in which compound?
water