Biology Chapter 6

What step of aerobic respiration generates the most ATP?

Electron transport chain

What is the final electron acceptor of aerobic respiration?

Oxygen

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

What pathway of aerobic respiration is shown in the image?

the electron transport chain

Match each component of aerobic respiration with the correct number of ATP generated during the passage of one molecule of glucose.

theoretical total - 36 ATP glycolysis - produces 4 ATP but requires 2 ATP; so net 2 ATP are produced Krebs cycle - 2 ATP electron transport - 34 ATP

The actual yield of ATP per 1 molecule of glucose that completes aerobic respiration is about ______ ATP.

30

About how much of the total energy stored in the chemical bonds of a molecule of glucose is transferred to and stored in the ATP molecules made during aerobic cellular respiration?

32%

The energy from electron transfers is used by some of the proteins in the electron transport chain to pump ______ into the intermembrane compartment of a mitochondrion.

H+

Select all of the following that are products of the "transition step" in aerobic cellular respiration. NAD+ NADH acetyl CoA CO2 pyruvate

NADH acetyl CoA CO2

During fermentation, ______ reduces pyruvate and is oxidized to NAD+, which can then be used in glycolysis.

NADH

Select all the products of glycolysis and the Krebs cycle that carry electrons to the electron transport chain in aerobic respiration. C6H12O6 (glucose) NADH FADH2 O2

NADH FADH2

The electron transport chain harnesses the potential energy of the molecules ______, which donate electrons to proteins in the electron transport chain.

NADH and FADH2

Select all of the following that can be a final electron acceptor in anaerobic respiration.

NO3- SO42-

Select all of the following that cause the difference between the theoretical and actual yields of ATP in aerobic respiration. ATP is spent transporting NADH out of the mitochondrial matrix. Protons leak across the inner mitochondrial membrane without using ATP synthase. Lipid molecules in cells slow down the function of respiration enzymes. ATP is spent transporting ADP and pyruvate into the mitchondrial matrix.

Protons leak across the inner mitochondrial membrane without using ATP synthase. ATP is spent transporting ADP and pyruvate into the mitchondrial matrix.

At the beginning of the Krebs cycle, acetyl CoA loses its coenzyme, and the two-carbon acetyl group combines with a four-carbon molecule, producing a six-carbon molecule called

citrate.

In what pathway is ATP produced in glycolysis but the NADH product of glycolysis does not enter an electron transport chain?

fermentation

Select the two pathways that generate ATP from glucose without requiring oxygen.

fermentation (with glycolysis) anaerobic respiration

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.

four

Glycolysis generates ______ ATP molecule(s), but requires an input of ______ ATP molecule(s), producing a net of 2 ATP molecules per glucose.

four; two

The polysaccharides starch and glycogen can be broken down into what monomer that enters the cellular respiration pathway?

glucose

Select all of the following that are required for glycolysis to occur. glucose oxygen ATP FAD

glucose ATP

Select all of the molecules that are reactants of glycolysis. Multiple select question. pyruvate glucose NADH NAD+

glucose NAD+

Approximately 32% of the potential energy in a molecule of glucose is captured in ATP through aerobic respiration; the remainder is lost as

heat.

Select all of the following that are reactants of pyruvate oxidation during the "transition step" of cellular respiration. acetyl CoA CO2 ATP pyruvate NAD+

pyruvate NAD+

Select all of the following that are produced by glycolysis. glucose pyruvate carbon dioxide NADH ATP

pyruvate NADH ATP

In the electron transport chain, electrons are shuttled through a series of membrane proteins, which creates a gradient of

hydrogen ions.

Glycolysis can occur

in both aerobic and anaerobic conditions

Select all the food molecules that can be broken down into glucose monomers, which enter aerobic respiration at the beginning of glycolysis.

starch glycogen

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.

Pyruvate is the product of glycolysis, and after it moves into the ______, it is oxidized to form ______, which enters the Krebs cycle.

mitochondrial matrix; acetyl CoA

When carbohydrate supplies are depleted in cells, amino acids from proteins can enter aerobic respiration after ______ is removed from the amino acids and excreted.

nitrogen

The reactions of the Krebs cycle ______ citrate as they produce ______.

oxidize; CO2, NADH, and FADH2

In aerobic respiration, the final electron acceptor, ______, combines with hydrogen ions to form water.

oxygen

Select all the molecules that have stored potential energy and that can be used in aerobic respiration to generate ATP. proteins carbon dioxide water lipids carbohydrates

proteins lipids carbohydrates

The ______ established by the electron transport chain powers the production of ATP using the enzyme ATP synthase.

proton gradient

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

In the last stage of cellular respiration, protons moving down their concentration gradient back into the mitochondrial matrix through ______ drive the production of ATP.

ATP synthase

Anaerobic respiration and fermentation are two pathways that generate ______ in the absence of ______.

ATP; oxygen

Select all of the following that are produced during the pathway of alcoholic fermentation.

CO2 ethanol NAD+

The electron transport chain accepts energy-rich electrons from ______ and ______ produced in the previous reactions of aerobic respiration.

FADH2 NADH

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.

FADH2 NADH CO2 ATP

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

______ 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

During which step of aerobic respiration is glucose split into two 3-carbon molecules?

Glycolysis

Match the aerobic respiration step with the correct location where it occurs in the cell in prokaryotes (bacteria and archaea) and eukaryotes. Instructions

Krebs cycle in prokaryotes = cytosol Krebs cycle in eukaryotes = mitochondrial matrix electron transport in prokaryotes = cell membrane electron transport in eukaryotes = inner mitochondrial membrane

In lactic acid fermentation, NADH reduces pyruvate, and the products are ______ and lactic acid.

NAD+

What occurs during the "energy investment" stage of glycolysis?

Two molecules of ATP are used to activate glucose.

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 product of pyruvate oxidation enters the Krebs cycle?

acetyl CoA

When energy levels are sufficient, the molecule ______ can be diverted from the Krebs cycle and used to form fat molecules for long-term energy storage.

acetyl CoA

Select all of the molecules that amino acids can be converted to when entering the energy pathways of cellular respiration.

acetyl CoA an intermediate in the Krebs cycle pyruvate

The Krebs cycle produces ATP, NADH, FADH2, and releases ______, which contains the carbon atoms remaining from the original 6-carbon glucose molecule.

carbon dioxide

Some proteins in the ______ use the energy of the electrons donated by NADH and FADH2 to pump protons (H+) into the intermembrane compartment of the mitochondrion.

electron transport chain

NADH and FADH2 transfer ______ from the reactants of glycolysis and the Krebs cycle to the electron transport chain of aerobic respiration.

electrons

Alcoholic fermentation produces a molecule called

ethanol.