BIO 2170 Ch 7 Pre-class questions
After pyruvate oxidation, the chemical energy of how many carbons of the original glucose molecule is converted to chemical energy in the form of ATP in the remaining steps of cellular respiration?
4
The majority of cells within the human body have a very high baseline amount of ATP, so cells are always prepared for any long-term activity. T/F
False
When glucose is broken down in a cell, all of the energy it stores is released simultaneously, not in a stepwise process. T/F
False
Which of the following statements is true regarding aerobic respiration? Aerobic respiration requires oxygen at every stage of the process. Aerobic respiration is carried out by all prokaryotes and eukaryotes. Aerobic respiration is a three-stage process, with oxidative phosphorylation comprising the last stage. Carbon dioxide is produced at every stage of aerobic respiration. None of the other answer options is correct.
None of the other answer options is correct.
Glycolysis is: aerobic. anaerobic. aerobic in some organisms but anaerobic in others. aerobic in some tissues but anaerobic in others. None of the other answer options is correct.
anaerobic.
Which was likely the first of the following metabolic pathways or structures to evolve?
fermentation
In cellular respiration, oxygen:
gains electrons and is an oxidizing agent
Fermentation takes place:
in the cytoplasm.
Pyruvate oxidation is an important stage in cellular respiration because:
it links glycolysis with the citric acid cycle.
During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____.
oxidation; NADH
The 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
Imagine that you exhale after a deep breath. Which of the following are you not exhaling?
waste products of glycolysis
During fermentation, pyruvate is:
reduced
The _____ forms of the electron carriers NAD+/NADH and FADH/FADH2 have high potential energy.
reduced
Which of the following correctly lists the approximate number of ATP produced by (i) beta-oxidation of a 16-carbon fatty acid, (ii) glycolysis and fermentation of a single glucose, and (iii) aerobic respiration of a single glucose, in that order?
106, 2, 32
A single molecule of glucose requires _____ "turn(s)" through the citric acid cycle for its chemical energy to be completely harvested.
2
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
The enzyme phosphofructokinase-1 (PFK-1) is thought of as a metabolic "valve" that regulates the rate of glycolysis. Which of the following correctly identifies its allosteric activators and inhibitors and their actions?
ADP—activator; citrate—inhibitor
Beta-oxidation of fatty acids does not directly produce:
ATP
A researcher is studying a population of eukaryotic cells. He notices that—regardless of the presence of ATP or ADP—the PFK-1 enzyme fails to function properly. Why? These cells may carry a mutation that alters the active site of the PFK-1 enzyme. These cells may carry a mutation that affects binding sites of the PFK-1 enzyme. These cells may carry a mutation that causes an over-production of citrate. All of the above
All of the above
Which of the following statements are true regarding pyruvate oxidation? This process occurs within the matrix of mitochondria. This process constitutes the second stage of cellular respiration. The process produces both CO2 and acetyl-CoA. The process yields no ATP via substrate-level phosphorylation. All of these choices are correct.
All of these choices are correct
By the time pyruvate is formed, most of the energy contained in glucose has been released. T/F
False
During the action of ATP synthase, the kinetic energy of the proton gradient is transformed into potential energy.
False
During the action of ATP synthase, the kinetic energy of the proton gradient is transformed into potential energy. T/F
False
Fermentation produces nearly two times as much ATP as aerobic respiration, which explains why it is a preferred pathway for bacteria. T/F
False
In a plant cell, all stages of cellular respiration are carried out in the cytoplasm. T/F
False
Like glycolysis, pyruvate oxidation produces both pyruvate and acetyl-CoA. These two products feed directly into the citric acid cycle and are the reactants for the cycle. T/F
False
Malate is both the starting and ending product of the citric acid cycle. t/f
False
Pyruvate oxidation is remarkably similar to glycolysis in that when one molecule of pyruvate enters into a mitochondrion, two molecules of acetyl-CoA are formed. T/F
False
Pyruvate oxidation produces a large amount of ATP. T/F
False
Imagine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation?
Glucose could move out of the cell, slowing cellular respiration.
_____ is found in animals, and possesses a large, central protein. _____ is found in plants, and lacks a central protein.
Glycogen; Starch
The inputs to glycolysis do not include: ADP. Pi. NADH. glucose. NAD+.
NADH
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.
The inputs to glycolysis do not include: ADP. Pi. NADH. glucose. NAD+
NADH
Which of the following statements is true regarding a reducing agent? It gains electrons. It is usually oxygen. It is never oxidized. It is an electron acceptor. It loses electrons.
It loses electrons.
We consume a variety of carbohydrates that are digested into a variety of different sugars. How do these different sugars enter glycolysis?
Sugars are converted to various forms and enter glycolysis at various stages.
Which of the following statements is true regarding the equation C6H12O6 + 6O2 →6CO2+ 6H2O + energy? The oxygen atoms in both CO2 and H2O are electronegative, and glucose is considered a reducing agent. The oxygen atoms in both CO2 and H2O are electronegative. Glucose could be considered a reducing agent. In the production of CO2 from glucose, the oxygen atoms lose electrons and the carbon atom is oxidized. The movement of hydrogen atoms in reactions involving C6H12O6 and H2O yields no information regarding the movement of electrons.
The oxygen atoms in both CO2 and H2O are electronegative, and glucose is considered a reducing agent
A researcher is studying a population of bacteria that carry out the citric acid cycle, but do so in reverse. What statements are likely true of these bacteria?
These bacteria will produce sugars from intermediates of the citric acid cycle.
Although cellular respiration is typically thought of as an aerobic process, glycolysis itself is actually anaerobic. T/F
True
Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is due to the fact that glycolysis is—at first—endergonic. t/f
True
The ATP produced during glycolysis is the result of substrate-level phosphorylation.
True
Energy released by transferring electrons along the electron transport chain is stored as potential energy in the form of:
a proton gradient
Lactic acid fermentation occurs in: Select all that apply. animals and fungi. plants and bacteria. fungi and bacteria. bacteria and animals. animals and plants.
bacteria and animals.
How did the earliest organisms on Earth most likely produce ATP?
by glycolysis
Cellular respiration is a series of _____ reactions.
catabolic
Phosphorylating glucose during phase 1 of glycolysis:
destabilizes the glucose molecule so that it can be broken down in phase 2
During what phase of glycolysis is NADH formed?
during phase 3, when glyceraldehyde 3-phosphate is phosphorylated
In the first three stages of cellular respiration, the chemical energy in glucose is transferred to:
electron carriers and ATP
The proteins of the electron transport chain are:
embedded in the inner mitochondrial membrane
The first phase of glycolysis requires the input of two ATP molecules. It is therefore:
endergonic
During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:
less energetic than the acetyl group
The chemical bonds of carbohydrates and lipids have high potential energy because: they are easy to phosphorylate. they are strong oxidizing agents. many of these bonds are C—C and C—H bonds. they are easy to hydrolyze. they are strong reducing agents.
many of these bonds are C—C and C—H bonds
In eukaryotes, pyruvate oxidation takes place in the:
mitochondrial matrix
In what organelle is pyruvate oxidation carried out in a cell?
mitochondrion
Which of the following is not an end product for an acetyl group that enters the citric acid cycle? oxaloacetate FADH2 CO2 NADH ATP
oxaloacetate
When an electron is transferred from NADH to CoQ, NADH is _____ and CoQ is _____.
oxidized; reduced
The final electron acceptor of the electron transport chain is:
oxygen
In the second phase of glycolysis: ATP is generated by oxidative phosphorylation. ATP is generated by substrate-level phosphorylation. NAD+ is reduced to NADH. phosphorylated sugar molecule is cleaved and the products rearranged. phosphate groups are added to glucose.
phosphorylated sugar molecule is cleaved and the products rearranged
Which stage of cellular respiration occurs immediately after pyruvate is produced?
pyruvate oxidation
Fermentation occurs in
some aerobic organisms, such as yeast, even in the presence of oxygen
In glycolysis, ATP is synthesized by:
substrate-level phosphorylation
Recall that the citric acid cycle starts with a four-carbon molecule, but that most of its intermediates are molecules that contain six carbons. How is this possible?
through the reaction of acetyl-CoA and oxaloacetate
Coenzyme Q and cytochrome c: transfer electrons between protein complexes of the electron transport chain. transfer high-energy electrons from NADH and FADH2 to protein complexes of the electron transport chain. transfer electrons to ATP synthase. transfer electrons to oxygen at the end of the electron transport chain. None of the other answer options is correct.
transfer electrons between protein complexes of the electron transport chain
At the end of glycolysis, the carbon molecules originally found in the starting glucose molecule are in the form of:
two pyruvate molecules
