Mastering Bio Chapter 6
Which of these enters the citric acid cycle (also called the Krebs cycle)?
Acetyl CoA
Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)?
Acetyl CoA
The overall equation for the cellular respiration of glucose is
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy.
The electron transport chain is, in essence, a series of redox reactions that conclude cellular respiration. During these redox reactions, __________.
electrons are transferred through a series of electron acceptors embedded within the inner mitochondrial membrane
In muscle cells, fermentation produces _____.
lactate and NAD+
In cellular respiration, glucose _____ electrons, whereas _____ electrons.
loses ... oxygen gains
A molecule that functions as the electron donor in a redox reaction __________
loses electrons and becomes oxidized
The electron transport chain is a series of electron carrier molecules. In eukaryotes, where can this structure be found?
mitochondria
The enzymes of the citric acid cycle are located in the
mitochondrial matrix and inner mitochondrial membrane
How many NADH are produced by glycolysis?
2
In glycolysis there is a net gain of _____ ATP.
2
During glycolysis, a molecule of glucose is partially oxidized. What is the net gain of ATP and NADH for each glucose molecule during this chemical pathway?
2 ATP and 2 NADH
The energy released from the redox reactions in the electron transport chain is used by the cell to make
ATP
In the first stage of cellular respiration (glycolysis), two molecules of pyruvate are produced. In the remaining stages of cellular respiration, a number of additional products are produced, such as __________. These other stages occur in the __________.
ATP ... mitochondria
Which of the following statements regarding aerobic cellular respiration is TRUE?
Glucose is completely oxidized to form carbon dioxide.
A muscle cell deprived of molecular oxygen will convert glucose to lactic acid to __________.
recycle NADH through fermentation
In cellular respiration, oxygen becomes _______ to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose.
reduced
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____.
substrate-level phosphorylation
For each glucose that enters glycolysis, _____ NADH enter the electron transport chain.
10
Substrate-level phosphorylation directly generates ATP during a chemical reaction. As a single molecule of glucose is completely oxidized in the presence of oxygen, what is the net yield of molecules of ATP made by substrate-level phosphorylation?
4 ATP
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
A compound called coenzyme A binds to a two-carbon fragment.
In cellular respiration, which of the following outcomes is the result of electrons moving through the electron transport chain (or its components)?
A proton gradient is formed.
In glycolysis, what starts the process of glucose breakdown?
ATP
Which of these is NOT a product of glycolysis?
FADH2
Where do the reactions of the citric acid cycle occur in eukaryotic cells?
The mitochondrion
What is the ultimate fate of the electrons that are stripped from glucose during cellular respiration?
They are used to form water.
A small amount of ATP is made in glycolysis________
by the transfer of a phosphate group from a fragment of glucose to ADP (substrate-level phosphorylation)
A culture of bacteria is fed glucose containing radioactive carbon and is then examined. During the citric acid cycle, radioactive carbon would first appear in
citrate
Each turn of the citric acid cycle generates one ATP and ___ additional energy-rich molecules: __________.
four; 3 NADH and 1 FADH2
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
In cellular respiration, glucose becomes ________ to carbon dioxide (CO2) as it loses electrons (in hydrogen atoms).
oxidized
Glycolysis is the only stage of cellular respiration that __________.
requires ATP to make ATP
As electrons move through the mitochondrial space
the pH of the intermembrane space changes.
In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive carbon. The mice were closely monitored, and in a few minutes, radioactive carbon atoms showed up in __________.
Carbon dioxide
The O2 required for __________ is supplied by __________.
Cellular respiration ... breathing
Given the relatively modest number of calories burned by anything but the most vigorous activities, why can people consume over 2,000 kilocalories a day, yet maintain a healthy body weight?
Most of the energy consumed in food is spent maintaining the body's functions, so only a fraction of food energy needs to be burned in exercise.
In cellular respiration, organic molecules become oxidized as ______ picks up electrons and H+ and becomes reduced to NADH.
NAD+
In the absence of oxygen, cells need a way to regenerate which compound?
NAD+
At the end of the citric acid cycle, most of the energy remaining from the original glucose is stored in
NADH
As shown below, an electron carrier, such as __________, acts as an energy-storage molecule when it is __________. The figure shows a chemical equation of respiration. Here, a glucose molecule reacts with six oxygen molecules. The products are six carbon dioxide molecules, six water molecules, and ATP with heat.
NADH ... reduced
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
During fermentation, __________ that was produced during glycolysis is converted back to __________.
NADH; NAD+
Which of the following statements regarding the movement of electrons during cellular respiration is true?
O2 is reduced when it accepts electrons and forms water.
Arsenic is a poison that binds to a molecule needed to build acetyl CoA. Based on this information, which part of cellular respiration would be stopped if arsenic were ingested?
citric acid cycle
The transfer of ___________ from one molecule to another is an oxidation-reduction reaction, or redox reaction.
electrons
Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria?
electrons
The mitochondrial cristae are an adaptation that
increases the space for more copies of the electron transport chain and ATP synthase complexes.
When a car engine burns gasoline, the results of the reaction are similar to when cells burn glucose. Both reactions release carbon dioxide and water. In cells, the chemical energy in food is converted to ATP and heat. In a moving car, the chemical energy in gasoline is converted to __________.
kinetic energy and heat
Oxidative phosphorylation could not occur without glycolysis and the citric acid cycle, because _____.
these two stages supply the electrons needed for the electron transport chain
NADH delivers electrons to an electron transport chain, which passes the electrons through carrier molecules in a series of redox reactions to the final electron acceptor, _____.
Oxygen
The final electron acceptor of cellular respiration is _____.
Oxygen
