Bio-1201 Chapter 9: Cellular Respiration and Fermentation

A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?

Catabolic processes will be activated to generate additional ATP.

Most CO2 from catabolism is released during ________.

citric acid cycle

Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?

FADH2

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

It serves as the final acceptor for electrons from the electron transport chain.

The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?

Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?

NAD+ becomes reduced.

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?

They are lethargic and readily tire from exercise.

Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?

They contain many electrons associated with hydrogen atoms.

If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?

12.5

Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?

fatty acids

In chemiosmosis, the most direct source of energy used to convert ADP + Pi to ATP is energy released ________.

from movement of protons through ATP synthase, down their electrochemical gradient

When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.

oxidized

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?

2 NADH, 2 pyruvate, and 2 ATP

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?

30-32

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?

ATP, CO2, and ethanol

Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate?

Acetyl CoA

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the ________.

H+ concentration across the membrane holding ATP synthase.

Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction?

It loses a hydrogen atom and loses potential energy.

Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?

mitochondrial intermembrane space

Assume that it is possible to label each of the molecules below with 18O a heavy isotope of oxygen. As a result of cellular respiration, water containing 18O would most quickly be detected if cells are provided with which one of the following molecules labeled with 18O?

molecular oxygen (O2)

Inhibition of which of the following metabolic pathways would result in decreased rates of CO2 production?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below?

oxidative phosphorylation

Which of the following processes is driven by chemiosmosis?

oxidative phosphorylation

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is ________.

O2

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following?

allosteric regulation

In mitochondria, exergonic redox reactions ________.

provide the energy that establishes the proton gradient

Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria?

pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space

When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.

reduced, and energy is released

A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?

released as CO2 and H2O

Which of the following best predicts the effect of removal of oxygen from a facultative anaerobic organism's environment?

glucose consumption increases, while the growth rate decreases

Which of the following sequences describes the path by which electrons move from high- energy to lower-energy molecules in aerobic respiration?

glucose → NADH → electron transport chain → oxygen

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

glycolysis

Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability?

glycolysis

Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?

glycolysis and fermentation

In which reactions of cellular respiration does substrate-level phosphorylation occur?

in both glycolysis and the citric acid cycle

If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?

inner membrane

Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis?

two molecules of ATP are used, and four molecules of ATP are produced

Which of the following statements best describes the electron transport chain?

It consists of a series of redox reactions.

Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?

citric acid cycle

If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?

1/3

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?

ATP and citrate

New biosensors, applied like a temporary tattoo to the skin, can alert endurance athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate present in sweat during strenuous exercise. Which of the statements below best explains the use of lactate as an indicator of exercise capacity?

During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.

Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules?

NADH

Which of the following products result from the oxidation of pyruvate to acetyl-CoA?

NADH and CO2

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?

The inside of the vesicles will become acidic.

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?

all of the electron transport system and ATP synthase

What types of cells carry out ATP synthesis by chemiosmosis?

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Which of the following types of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?

coupling of an endergonic reaction to an exergonic reaction

Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?

directly entering the citric acid cycle

When a cell is deprived of oxygen, which of the following processes will be inhibited first?

electron transport chains

Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy?

glucose

Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?

in all cells, with or without light

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?

oxidation of NADH to NAD+

In the following reaction which molecule functions as the oxidizing agent? Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

Which of the following events takes place in the electron transport chain?

the harnessing of energy from redox reactions to generate a proton gradient

Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?

100%

Which of the summary statements below best describes the results of the following reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy

C6H12O6 is oxidized and O2 is reduced.

A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?

Its cells cannot transport pyruvate from the cytosol into the mitochondria

Depletion of which of the following molecules from the mitochondria will most directly inhibit the citric acid cycle?

NAD+

Which of the following statements best describes a characteristic of NAD+?

NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The pH of the matrix increases.