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AP Bio Chapter 9

Cellular Respiration: Harvesting Chemical Energy
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A molecule becomes more oxidized when it_________.
loses an electron
In the overall process of glycolysis and cellular respiration, ______ is oxidized and ______ is reduced.
glucose; oxygen
Most of the ATP produced in cellular respiration comes from which process?
Oxidative phosphorylation
Oxygen gas is one of the strongest oxidizing agents known. The explanation for this is that _________.
the oxygen atom is very electronegative
The funtion of cellular respiration is to _______.
extract usable energy from glucose
During the reaction C₆H₁₂O₆ + O₂ --> 6 CO₂ + 6 H₂O, which compound is reduced as a result of the reaction?
Oxygen
What is the best explanation for why the oxidation of organic compounds by molecular oxygen (O₂) yields so much energy?
The oxygen atom has a higher affinity for electrons than the carbon atom.
What happens to the rest of the energy in glucose that isn't used in cellular respiration?
It is converted to heat.
A small amount of ATP is made in glycolysis by which process?
Substrate-level phosphorylation
What is the transfer of a phosphate group from a fragment of glucose to ADP called?
Substrate-level phosphorylation
A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. However, he cannot do this because________.
human cells must also perform glycolysis; the drug might also poison them.
In glycolysis, there is no production of carbon dioxide as a product of the pathway. What is the best explanation for this?
The two pyruvate molecules produced from each glucose molecule each contain three carbon atoms.
Of the following molecules in glycolytic pathway (the process of glycolysis), the one with the most chemical energy is______.
fructose-1, 6-biphosphate
During respiration in a eukaryotic cell, reactions of glycolysis ocur ______.
in the cytosol
What is the name of the process in which glucose is converted to pyruvate with the production of ATP and NADH?
Glycolysis
most of the NADH that delivers electrons to the electron transport chain comes from which of the following?
The citric acid cycle
In an experiment, mice were fed glucose containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in ______.
Carbon dioxide
In preparing pyruvate to enter the citric acid cycle, which of the following steps does occur?
It's oxidized, and the resulting electrons reduce an NAD+ to an NADH, a carbon atom is released in carbon dioxide, and a coenzyme A binds to a two-carbon fragment.
Why is the citric acid cycle called a cycle?
The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.
In the citric acid cycle, for each pyruvate that enters the cycle, 1 ATP, 3 NADH, and 1 FADH₂are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH₂are produced in the citric acid cycle?
2 ATP, 6 NADH, 2 FADH₂
During respiration in eukaryotic cells, reactions of the citric acid cycle occur _______.
in the matrix of the mitochondrion
How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?
4 ATP
Which of the following represents the major energy accomplishment of the citric acid cycle?
Formation of NADH and FADH₂
After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of______.
NADH
What accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle?
Formation of CO₂and NADH
The energy given up by electrons as they move through the electron transport chain is used in which process?
Pumping H+ across a membrane
The ATP synthase in a human cell obtains energy for making ATP directly from which process?
The flow of H+ across a membrane through the ATP synthase enzyme
When a poison blocks the electron transport chain, glycolysis and the citric acid cycle soon grind to a halt as well. What is the best explanation for this?
NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.
What sequence correctly describes the synthesis of ATP associated with electron transport in mitochondria?
NADH, electron transport, proton gradient, chemiosmosis
Most of the electrons removed from glucose by cellular respiration are used for what process?
Reducing NAD+ to NADH in glycolysis and the citric acid cycle and producing a proton gradient for ATP synthesis in the mitochondria.
Which part of the cellular catabolism of glucose requires molecular oxygen and produces CO₂?
The combination of the citric acid cycle and electron transport
During aerobic respiration, molecular oxygen is used for which purpose?
To accept electrons and form H₂O at the end of the electron transport chain.
What substances are involved in oxidative phosphorylation?
ADP, oxygen, and ATP.
What best describes the electron transport chain?
Electrons are passed from one carrier to another, releasing a little energy at each step.
If a compound that allows protons to freely diffuse across membranes is added to cells that are actively metabolizing glucose via cellular respiration, what processes would stop?
No processes would stop.
What is the source of the energy that produces the chemiosmotic gradient in mitochondria?
Electrons moving down the electron transport chain.
During respiration in eukaryotic cells, the electron transport chain is located in or on the _______.
inner membrane of the mitochondrion
the overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately _____.
40%
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step ______.
enables the cell to recycle NAD+
Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were funtioning anaerobically. They could do this by checking for a build-up of which compound?
Lactate
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
NAD+
Muscle tissues make lactate from pyruvate to___________.
regenerate NAD+
In brewing beer, maltose is______.
the substrate for alcoholic fermentation
If muscle cells in the human body consume O₂faster than it can be supplied, what is likely to result?
The muscle cells will have more trouble making enough ATP to meet their energy requirements, the cells won't be able to carry out oxidative phosphorylation, and the cells will consume glucose faster.
Of all the metabolic pathways, which is the only pathway found in all organisms?
Glycolysis
When protein molecules are used as fuel for cellular respiration, ______ are produced as waste.
amino groups
A gram of fat oxidized by respiration produces approximately twice as much ATP ass a gram of carbohydrate. What best explains this observation?
Fats are better electron donors to oxygen than are sugars.
If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, what will result?
Less ATP and CO₂will be produced and the four-carbon compound that combines with acetyl CoA will have to be made by some other process.
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