Bio : Chapter 6
Besides sugars and fats, organisms can use other molecules as fuel for cellular respiration. When protein molecules are used, __________ are produced as waste.
amino groups
An organism that can use energy from the sun to directly produce food is called a(n) _______.
autotroph
Each turn of the citric acid cycle processes one two-carbon acetyl molecule, which generates one ATP and ___ additional energy-rich molecules: __________.
four; 3 NADH and 1 FADH2
A molecule that functions as the electron acceptor in a redox reaction __________.
gains electrons and becomes reduced
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell?
glucose
How is breathing and cellular respiration closely related?
Breathing supplies O2 for use in cellular respiration and removes CO2
How do the mitochondria of brown fat cells differ from those of other cells?
Ion channels in the inner mitochondrial membrane prevent the formation of a H+ gradient.
Cellular respiration requires fuel (glucose) and oxygen gas. The main process that produces these inputs is _____.
photosynthesis
During ________, the energy from the sun is used to make sugar molecules.
photosynthesis
In oxidative phosphorylation, electrons are passed from one electron carrier to another. The energy released is used to __________.
pump protons (H+) across the mitochondrial membrane
Stage 2 of cellular respiration
pyruvate oxidation and the citric acid cycle: complete the breakdown of glucose to carbon dioxide
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
Which step of the citric acid cycle requires both NAD+ and ADP as reactants?
step 3
brown fat
"baby fat" that consumes oxygen, but generates heat
Oxidative phosphorylation is responsible for nearly all the ATP produced in your body. Select the three true statements about oxidative phosphorylation.
- Without oxygen, oxidative phosphorylation would not occur. - Chemiosmosis is the final step in oxidative phosphorylation. - NADH and FADH2 deliver electrons to the electron transport chain during oxidative phosphorylation.
Events of Electron Transport Chain
1) Oxidation of NADH 2) Electrons enter the electron transport chain 3) Release of energy for ATP synthesis 4) Electrons leave the electron transport chain 5) Reduction of oxygen and formation of water
For each glucose that enters glycolysis, _____ NADH enter the electron transport chain.
10
In glycolysis, what starts the process of glucose breakdown?
ATP
The energy released from the redox reactions in the electron transport chain is used by the cell to make _______.
ATP
Which energy-rich molecule produced by cellular respiration directly powers cell work?
ATP
_______ is the high-energy molecule used to power cellular work.
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
Imagine an organism with mutations in complexes I, III, and IV that prevent pumping of hydrogen ions into the intermembrane space but still allow electrons to pass through the electron transport chain. Which of the following is the most likely consequence of these mutations?
ATP synthase will not convert ADP to ATP.
What is the correct general equation for cellular respiration?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy
What is the correct general equation for photosynthesis?
CO2 + H2O + sunlight → O2 + sugar
site of photosynthesis
Chloroplast
Adequate nutrition is important for human infants to maintain their layer of brown fat; malnourished infants have depleted brown fat amounts. On average, what should be observed in malnourished compared to healthy human infants?
Cooler body temperatures than healthy infants when both are exposed to cool temperatures.
What occurs as electrons pass through the multiple carrier molecules of the electron transport chain?
Energy is released in a stepwise fashion.
Which of these is NOT a product of glycolysis?
FADH2
Which of the following statements regarding glycolysis is FALSE?
Glycolysis evolved in an oxygen-rich environment.
Given the relatively modest number of calories burned by anything but the most vigorous of activities, how 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 over the course of a day, so a healthy amount of daily exercise would require only a modest increase in the number of kilocalories consumed to maintain a healthy weight.
In cellular respiration, organic molecules become oxidized as _______ picks up electrons and H+ and becomes reduced to NADH.
NAD+
The coenzyme acting as an electron shuttle before it has accepted electrons is _________
NAD+
The electron shuttle after it has accepted electrons is _________.
NADH
What molecule releases the electrons used in the electron transport chain?
NADH
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
What is the difference between where photosynthesis and cellular respiration takes place?
Photosynthesis takes place in some prokaryotes while cellular respiration takes place in many prokaryotes and almost all eukaryotes
What is the purpose of embedding the electron transport chain in the membrane of a cell?
The electron acceptors can transport H+ across the membrane, which is otherwise impermeable to H+.
Which statement describes the citric acid cycle?
This process produces some ATP and carbon dioxide in the mitochondrion. Submit
Which statement describes glycolysis?
This process splits glucose in half and produces 2 ATPs for each glucose.
Which statement describes the electron transport chain?
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
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
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
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
reactants of photosynthesis
carbon dioxide and water
products of cellular respiration
carbon dioxide, water, and ATP
During ________, the energy in sugar molecules is used to make molecules of ATP.
cellular respiration
The transfer of _______ from one molecule to another is an oxidation-reduction reaction, or redox reaction.
electrons
Glycolysis is the multi-step breakdown of _____. Several different _____ play a role in this process.
glucose ... enzymes
During cellular respiration __________ is oxidized and __________ is reduced.
glucose ... oxygen
products of photosynthesis
glucose and oxygen
reactants of cellular respiration
glucose and oxygen
During cellular respiration, glucose is oxidized. However, an intermediate, __________, can be siphoned off and used to synthesize fats.
glyceraldeyhyde 3-phosphate
Which stage of cellular respiration appears to have evolved first?
glycolysis
Sequence of steps as energy is extracted from glucose during cellular respiration.
glycolysis → acetyl CoA → citric acid cycle → electron transport chain Submit
Stage 1 of cellular respiration
glycolysis: begins cellular respiration by breaking glucose into two molecules of a three-carbon compound called pyruvate
An organism that must consume other organisms to obtain nourishment is called a(n) _______.
heterotroph
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
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
During the first step of a redox reaction, what does the enzyme dehydrogenase strip from organic fuel?
hydrogen atoms
Unlike the Citric Acid cycle and electron transport, glycolysis occurs _____.
in the cytoplasm
Where does glycolysis occur in a eukaryotic cell?
in the cytoplasmic fluid; cytosol
We inhale O2 and we exhale CO2. Carbon dioxide is produced __________.
in the reaction that creates acetyl CoA (coenzyme A) from pyruvate
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
Recent data suggests that heat-generating brown fat is most active in __________.
lean people exposed to cold temperatures
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
Lungs are to breathing as __________ are to cellular respiration.
mitochondria
site of cellular respiration
mitochondria
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
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
mitochondrion
_______ is the loss of one or more electrons.
oxidation
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
Stage 3 of Cellular Respiration
oxidative phosphorylation
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, 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
A muscle cell deprived of molecular oxygen will convert glucose to lactic acid to __________.
recycle NADH through fermentation
When the loss and gain of electrons happen in sequence, it is called a(n) _________ reaction.
redox
In cellular respiration, oxygen becomes ________ to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose.
reduced
_______ is the gain of one or more electrons.
reduction
Glycolysis is the only stage of cellular respiration that __________.
requires ATP to make ATP
In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____.
substrate-level phosphorylation
Which part(s) of cellular respiration require(s) oxygen gas?
the Citric Acid cycle and the electron transport chain
Most NADH molecules generated during cellular respiration are produced during __________.
the citric acid cycle
cellular respiration
the process that breaks down food molecules and generates ATP
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
A gram of fat oxidized by cellular respiration produces approximately __________ as much ATP as a gram of carbohydrate.
twice
How many NADH are produced by glycolysis?
two
In glycolysis there is a net gain of _____ ATP.
two
What is/are the most important output(s) of glycolysis?
two pyruvic acid and two NADH molecules
Fat is the most efficient molecule for long-term energy storage, even compared to carbohydrates, because _____.
with their numerous hydrogen atoms, fats provide an abundant source of high-energy electrons
Fat is the most efficient molecule for long-term energy storage, even compared to carbohydrates, because __________.
with their numerous hydrogen atoms, fats provide an abundant source of high-energy electrons
Recall from Chapter 4 that phospholipids have two parts: a nonpolar head and two nonpolar tails. In an oil-based, nonpolar environment, phospholipids would arrange themselves so that they __________.
would stay together but in a reverse orientation, with their tails projecting outward
