Chapter 6 Homework
Which of the following best describes the electron transport chain?
Electrons pass from one carrier to another, releasing a little energy at each step : NADH and FADH2 deliver electrons from the breakdown products of glycolysis and the citric acid cycle to the electron transport chain, which passes these electrons from one molecule to another, releasing a small amount of energy at each step.
In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____.
substrate-level phosphorylation: A phosphate group is transferred from GTP to ADP.
In glycolysis, what starts the process of glucose breakdown?
ATP: Some ATP energy is used to start the process of glucose oxidation
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: Cellular respiration, or the oxidization of glucose, involves the release of CO2.
In cellular respiration, organic molecules become oxidized as ___________ picks up electrons and H+ and becomes reduced to NADH.
NAD+
For each glucose that enters glycolysis, _____ NADH enter the electron transport chain.
10 :For each glucose molecule that enters glycolosis, a total of 10 NADH are produced -- 2 are produced in glycolysis, 2 are produced in acetyl CoA production, and 6 are produced in the citric acid cycle.
In glycolysis there is a net gain of _____ ATP.
2
How many NADH are produced by glycolysis?
2 NADH
The energy released from the redox reactions in the electron transport chain is used by the cell to make ___________ .
ATP
What are 4 products of glycolysis?
ATP NADH + H+ Water pyruvate FADH: FADH2 is a product of the citric acid cycle.
Which of the following statements regarding glycolysis is FALSE?
Glycolysis evolved in an oxygen-rich environment.: does not require o2
In nutrient-rich environments (like your mouth), bacteria can use the provided amino acids to synthesize their proteins. However, should the environmental conditions change and become nutrient-poor, bacteria would need to synthesize their amino acids. They can do this using __________.
citric acid cycle intermediate
Each turn of the citric acid cycle generates one ATP and ___ additional energy-rich molecules: __________.
four; 3 NADH and 1 FADH: The citric acid cycle generates 3 molecules of NADH and 1 molecule of FADH2. These molecules carry high energy electrons that will be delivered to the electron transport chain.
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell?
glucose
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient: Concentration gradients are a form of potential energy.
In muscle cells, fermentation produces _____.
lactate and NAD+
In eukaryotes, most of the high-energy electrons released from glucose by cellular respiration __________.
reduce NAD+ to NADH, which then delivers them to the electron transport chain: Most of the high-energy electrons released from the glucose are picked up by NAD+ and sent through the electron transport chain.
Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)?
acetyl CoA: Acetyl CoA enters the citric acid cycle.
Which of these enters the citric acid cycle (also called the Krebs cycle)?
acetyl CoA: Acetyl CoA is a reactant in the citric acid cycle (also called the Krebs cycle).
Which energy-rich molecule produced by cellular respiration directly powers cell work?
atp:
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation: A phosphate group is transferred from glyceraldehyde phosphate to ADP.
A gram of fat oxidized by cellular respiration produces approximately __________ as much ATP as a gram of carbohydrate
twice
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. :
Bacteria have no membrane-enclosed organelles. However, some still generate ATP through cellular respiration. Where might the electron transport chain be found in these organisms?
plasma membrane
A single glucose molecule produces about 38 molecules of ATP through the process of cellular respiration. However, this only represents approximately 34% of the chemical energy present in this molecule. The rest of the energy from glucose is __________.
converted to heat
. The transfer of ________ from one molecule to another is an oxidation-reduction reaction, or redox reaction.
electrons
Most NADH molecules generated during cellular respiration are produced during __________.
the citric acid cycle: there are 6 NADH
The O2 required for __________ is supplied by __________.
cellular respiration ... breathing: Breathing supplies the O2 required for cellular respiration, and also disposes of the CO2 produced as a waste product during cellular respiration.
During electron transport, energy from _____ is used to pump hydrogen ions into the _____
NADH and FADH2 ... intermembrane space: The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.
Through respiration, humans breathe in O2 and breathe out CO2. However, what would happen if we did not breathe in O2?
We would not make enough ATP to meet our energy requirements
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 treat people with bacterial infections. However, he can't do this because _____.
human cells also perform glycolysis; the drug might also poison them
We inhale O2 and we exhale CO2. Carbon dioxide is produced __________.
in the reaction that creates acetyl CoA (coenzyme A) from pyruvate: Carbon dioxide is produced in the transition between glycolysis and the citric acid cycle when the three-carbon pyruvate is cleaved to a two-carbon acetyl molecule with the remaining carbon of pyruvate released as carbon dioxide. Carbon dioxide is also produced in the citric acid cycle itself.
Some human cells, such as nerve cells, are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then __________.
oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to "pull" the electrons down the transport chain
In cellular respiration, most ATP molecules are produced by _____
oxidative phosphorylation: This process utilizes energy released by electron transport.
In cellular respiration, glucose becomes __________ to carbon dioxide (CO2) as it loses electrons (in hydrogen atoms).
oxidized
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 : Oxygen is combined with electrons and hydrogen to form water.
In cellular respiration, oxygen becomes _________- to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose.
reduced
Sports physiologists at an Olympic training center want to monitor athletes to determine at what point their muscles begin to function anaerobically. They could do this by checking for a buildup of _____.
lactic acid: In humans, muscle cells switch to lactic acid fermentation after becoming anaerobic.
A scientist wants to study the enzymes of the citric acid cycle in eukaryotic cells. What part of the cell would she use as a source of these enzymes?
mitochondrial matrix: The water-soluble citric acid cycle intermediates and enzymes of a eukaryotic cell are found in the mitochondrial matrix, where the newly synthesized NADH and FADH2 diffuse to proteins of the electron transport chain held within the inner mitochondrial membrane. The matrix corresponds to the cytoplasm of the bacterium from which mitochondria are descended.
