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