chapter 6
If oxygen is present, most of the known organisms on Earth use the energy pathway ______, which generates the highest amount of ATP of all the energy pathways.
aerobic respiration
What cellular process uses glucose and oxygen to produce ATP?
aerobic respiration
After nitrogen is removed from the amino acids in protein-containing foods, the remainder of the amino acids can enter aerobic respiration pathways as what molecules?
an intermediate in the Krebs cycle acetyl CoA pyruvate
How is ATP formed during the Krebs cycle?
substrate-level phosphorylation
When the electron carrier molecules NADH and FADH2 enter ______, electrons are removed, and the energy pumps protons into the intermembrane compartment of the mitochondrion.
the electron transport chain
The oxidation of glucose during aerobic respiration yields ATP, NADH, and FADH2 molecules. In theory, the ATP yield during the electron transport chain is ______ molecules of ATP per NADH and ______ molecules of ATP per FADH2.
3 2
Although the theoretical yield of ATP per one molecule of glucose in aerobic respiration is about 36 ATP, the actual yield is about ______ ATP per glucose.
30
Before the NADH and FADH2 produced during glycolysis and the Krebs cycle are "cashed in" during the electron transport chain, the net number of ATP molecules produced per glucose molecule is ______ molecules.
4
Select all of the following that have been produced from the original glucose molecule after glycolysis, oxidation of pyruvate, and the Krebs cycle occur, but before molecules enter the electron transport chain.
NADH FADH2 ATP CO2
Select all of the following that are reactants of pyruvate oxidation during the "transition step" of cellular respiration.
NAD+ pyruvate
During fermentation, ______ reduces pyruvate and is oxidized to NAD+, which can then be used in glycolysis.
NADH
What electron carrier molecule is generated during the reactions of glycolysis?
NADH
Select the molecules that are products of the Krebs cycle.
NADH ATP carbon dioxide FADH2
Select all the products of glycolysis and the Krebs cycle that carry electrons to the electron transport chain in aerobic respiration.
NADH FADH2
Select all of the electron-carrier molecules produced by the Krebs cycle.
NADH (nicotinamide adenine dinucleotide) FADH2 (flavin adenine dinucleotide)
The electron transport chain harnesses the potential energy of the molecules ______, which donate electrons to proteins in the electron transport chain.
NADH and FADH2
The molecules ______ that are produced by glycolysis and the Krebs cycle must move to the inner mitochondrial membrane to enter the electron transport chain.
NADH and FADH2
The rearrangement and oxidation of intermediates in the Krebs cycle transfers electrons to what molecules?
NADH and FADH2
The first protein in the electron transport chain accepts electrons from ______, and the second protein in the electron transport chain accepts electrons from ______.
NADH; FADH2
Select reactions that occur during the first stage of glycolysis, called the energy investment stage, which consists of the first five reactions.
Phosphate is transferred to glucose. A 6-carbon intermediate is split into two 3-carbon molecules.
If a cell's carbohydrate supplies run low, ______ monomers of proteins can be converted into molecules that enter the pathways of cellular respiration.
amino acid
Prokaryotic organisms that use NO3-, SO42-, and CO2 as final electron acceptors in an energy pathway that generates ATP are conducting what energy pathway?
anaerobic respiration
What cellular process generates ATP and uses an inorganic molecule other than oxygen as the final electron acceptor of an electron transport chain?
anaerobic respiration
Plants conduct photosynthesis. Which of the following conduct cellular respiration?
animals and plants
Organisms in oxygen-rich environments use aerobic cellular respiration to generate
atp
The potential energy stored in food (such as glucose) is used by all organisms to make the energy-carrying molecule _ , which powers cellular activity.
atp
What molecule powers most energy-requiring cell activities, including active transport, movement of chromosomes and flagella, muscle contraction, and the synthesis of organic molecules?
atp
Glycolysis generates 4 _molecules per glucose, but requires an input of ATP molecule(s), producing a net of _ ATP molecules per glucose.
atp, 2
Select all the organelles that contain electron transport chains within their inner membranes or inner compartments and that are likely to have arisen from endosymbiosis of bacteria with electron transport chains on their cell membranes.
chloroplasts mitochondria
The first product of the Krebs cycle is the 6-carbon molecule citrate; hence, the Krebs cycle is also known as the ______ cycle.
citric acid
The organic product of photosynthesis, ______, is the reactant of cellular respiration.
glucose
What increases the surface area of the inner mitochondrial membrane?
cristae
Glycolysis occurs in the ______ of all living cells.
cytosol
True or false: Glucose is the only food molecule that can enter the pathways of aerobic respiration and lead to the production of ATP.
false
Select all the types of organisms that can rely on fermentation as the sole pathway for producing ATP.
microorganisms in sugar-rich environments single-celled organisms
If there are sufficient levels of ATP, organisms may store potential energy by diverting acetyl CoA away from the Krebs cycle and storing it as ______ molecules.
fats
______ have more calories per gram than any other food because a single molecule can yield dozens of acetyl CoA molecules that can enter the Krebs cycle.
fats
Select the two energy pathways that generate ATP from glucose without requiring oxygen.
fermentation (with glycolysis) anaerobic respiration
Cellular respiration harvests energy from ______ and uses the energy to power the synthesis of ______ from ADP and a phosphate group.
food molecules; ATP
Select all of the molecules that are reactants of glycolysis.
glucose NAD+
Select all the food molecules that can be broken down into glucose monomers, which enter aerobic respiration at the beginning of glycolysis.
glycogen starch
The monomers of starch and glycogen food molecules first enter aerobic respiration at what step?
glycolysis
Select all of the following that are stages of aerobic cellular respiration.
glycolysis electron transport chain Krebs cycle
Approximately 32% of the potential energy in a molecule of glucose is captured in ATP through aerobic respiration; the remainder is lost as
heat
In fermentation, ______ produced by glycolysis is reduced, and ______ is regenerated, which allows glycolysis to continue to produce a small amount of ATP.
pyruvate; NAD+
In the energy pathway called lactic acid fermentation, ______ is reduced to lactic acid, and NADH is oxidized to NAD+, which allows ______ to continue producing a small amount of ATP.
pyruvate; glycolysis
Select all of the following that are true of ATP synthesis.
requires an input of energy (endergonic reaction) a phosphate group is added to ADP
In the electron transport chain, energy from electron transfers powers the pumping of ______ into the intermembrane compartment by some of the proteins in the chain.
hydrogen ions
Glycolysis can occur
in both aerobic and anaerobic conditions.
The Krebs cycle not only produces ATP and electron carriers, but intermediate molecules formed in the Krebs cycle can also be used
in pathways that manufacture amino acids or fats.
Select organisms that are able to generate ATP by conducting anaerobic respiration, which includes an electron transport chain with an inorganic molecule other than oxygen as the final electron acceptor.
some archaeans some bacteria
What method is used to generate ATP in glycolysis?
substrate-level phosphorylation
True or false: Plants use a portion of the glucose they produce in photosynthesis to make ATP in cellular respiration.
true
True or false: The potential energy stored in glucose cannot be removed all at once or it will cause destruction of the cell.
true
The area between the outer and inner membranes of a mitochondrion is called the ______ compartment.
intermembrane
When there is no oxygen available to human muscle cells, the cells can continue to make ATP for a short time using glycolysis as part of
lactic acid fermentation.
How do organisms make ATP?
using potential energy stored in molecules
The anaerobic respiration pathway generates
less ATP than aerobic respiration.
The fluid enclosed within the inner membrane of a mitochondrion is called the
matrix
Within mitochondria, the Krebs cycle takes place in the
matrix
What organism conducts alcoholic fermentation?
yeast
In the cells of protists, plants, fungi, and animals, the Krebs cycle and the electron transport chain take place in organelles called
mitochondria.
Pyruvate is the product of glycolysis, and after it moves into the ______, it is oxidized to form ______ that enters the Krebs cycle.
mitochondrial matrix; acetyl CoA
What organelle in a eukaryotic cell provides most of the cell's ATP?
mitochondrion
Muscle soreness in humans is not likely due to a pH drop from fermentation because
muscle cells produce lactate, not lactic acid.
What byproduct of photosynthesis is used as the final electron acceptor of aerobic respiration?
o2
In aerobic respiration, the final electron acceptor, ______, combines with hydrogen ions to form water.
oxygen
Specialized organs such as gills or lungs help many organisms acquire what gas that is required for aerobic cellular respiration?
oxygen (O2)
In substrate-level phosphorylation, a molecule donates a(n) ______ group to ADP to form ATP, and a ______ is not required.
phosphate, proton gradient
Select molecules that have stored potential energy and that can be used in aerobic respiration to generate ATP.
proteins carbohydrates lipids
Enzymes separate the glycerol and fatty acids of fats in food molecules; then the glycerol is converted to ______, which is able to enter aerobic respiration.
pyruvate
In glycolysis, a glucose molecule is split into two molecules of ______, and energy is harvested as ATP and NADH.
pyruvate
Rank the following pathways in the order that they likely evolved, from the first one to evolve at the top to the last one to evolve at the bottom. Instructions
1 gly 2 photo wit h2o 3 photo with h2s 4 aero
Rank the types of metabolic pathways from smallest ATP production (at the top) to largest production of ATP (at the bottom). Position 1 of 3 fermentation (with glycolysis) correct toggle button unavailable fermentation (with glycolysis)
1, ferm 2, Anaaero 3, anaero
Rank the 3 groups of reactions of aerobic respiration in the order they occur, beginning with the first stage of cellular respiration at the top.
1. gly 2. kreb 3. etc
mitochondria.
ATP
Select all of the following that are products in the overall equation for aerobic respiration.
ATP (adenosine triphosphate) CO2 (carbon dioxide)
Select reactions that occur during the second stage of glycolysis, called the energy harvest stage and consisting of reactions 6 through 10.
ATP is generated by substrate-level phosphorylation. Two molecules of pyruvate are produced. NAD+ is reduced to NADH.
Select all of the following that cause the difference between the theoretical and actual yields of ATP in aerobic respiration.
ATP is spent transporting pyruvate and ADP into the mitchondrial matrix. Protons leak across the inner mitochondrial membrane without using ATP synthase.
What enzyme uses the energy of a proton gradient to add a phosphate to ADP?
ATP synthase
Select all of the following that are encoded by mitochondrial DNA.
ATP synthase proteins of the electron transport chain
ATP synthase is an enzyme that forms a channel for hydrogen ions to diffuse across a membrane and power the formation of
ATP.
Anaerobic respiration and fermentation are two pathways that generate ______ in the absence of ______.
ATP; oxygen
Select all of the products of cellular respiration that are used as reactants in photosynthesis.
CO2 H2O
Aerobic cellular respiration requires that ______ diffuses out of cells, and ______ diffuses into cells.
CO2; O2
In the picture, the arrows point to mitochondrial folds called
CRISTAE
What happens to the lactate produced by muscle cells that conduct fermentation to acquire ATP?
Cells consume it within a short time.
The electron transport chain accepts energy-rich electrons from ______ and ______ produced in the previous reactions of aerobic respiration.
FADH2 NADH
Why do scientists think glycolysis was probably the first energy pathway to evolve?
Glycolysis is conducted by nearly all organisms.
Match each product or result with its type of anaerobic respiration.
H2S byproduct -wetland bacteria that use SO42- as the electron acceptor in anaerobic respiration wetland bacteria that use SO42- as the electron acceptor in anaerobic respiration generate methane- archaea inside cow intestines that use CO2 as the electron acceptor in aerobic respiration archaea inside cow intestines that use CO2 as the electron acceptor in aerobic respiration results in production of nitrogen gas - bacteria living in water-logged soils that use NO3- as the electron acceptor in aerobic respiration bacteria living in water-logged soils that use NO3- as the electron acceptor in aerobic respiration
Intermediates from what pathway can be used in the manufacture of amino acids and fats?
Krebs cycle
Select all of the following steps of cellular respiration that generate ATP by substrate-level phosphorylation—that is, without a proton gradient.
Krebs cycle glycolysis
In lactic acid fermentation, NADH reduces pyruvate, and the products are ______ and lactic acid.
NAD+
What happens to the carbon atoms in the two-carbon acetyl group that enters the Krebs cycle?
They are released as CO2.
The potential energy of ______ is used to power the production of ATP in chemiosmotic phosphorylation.
a proton gradient
In the anaerobic energy pathway called ______, pyruvate from glycolysis is reduced, NADH is oxidized, and NAD+, ethanol, and CO2 are produced.
alcoholic fermentation
The fatty acids of fat molecules are converted into two-carbon molecules called ______, which can enter the Krebs cycle of aerobic respiration.
acetyl CoA
What molecule carries potential energy originally present in the chemical bonds of glucose and enters the Krebs cycle?
acetyl CoA
What product of pyruvate oxidation enters the Krebs cycle?
acetyl CoA
Select all of the following that are products of the "transition step" in aerobic cellular respiration.
acetyl CoA CO2 NADH
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP is the overall equation for what process?
aerobic respiration
The Krebs cycle produces ATP, NADH, FADH2, and releases ______, which contains the carbon atoms remaining from the original 6-carbon glucose molecule.
carbon dioxide
Select all of the cellular activities that require ATP.
cell movement protein synthesis active transport
When protons diffuse across a membrane through ATP synthase, energy is transferred to phosphorylate an ADP, making ATP in the process called ______ phosphorylation.
chemiosmotic
NADH and FADH2 transfer energy-rich ______ from the molecules of glycolysis and the Krebs cycle to the electron transport chain of aerobic respiration.
electron
In what step of aerobic cellular respiration do electrons pass through a series of membrane proteins, and the energy released by their passage is used to create a hydrogen ion gradient?
electron transport chain
What pathway of aerobic cellular respiration generates ATP by chemiosmotic phosphorylation?
electron transport chain
What step of aerobic respiration generates the most ATP?
electron transport chain
Chloroplasts and mitochondria, the sites of photosynthesis and cellular respiration, are thought to have arisen by
endosymbiosis of bacterial cells.
Alcoholic fermentation produces a molecule called
ethanol
