Chapter 9: Cellular Respiration, Chapter 6, Chapter 5: Membrane Transport & Cell Signaling (Multiple Choice) chp5-8

The overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately _____. (eText Concept 9.4)

35%

In brewing beer, maltose (a disaccharide of glucose) is _____. (eText Concept 9.5)

the substrate for alcoholic fermentation

Which of the following statements about allosteric proteins is/are true?

All of the first three listed responses are correct.

Which of the following statements about enzymes is INCORRECT?

An enzyme is consumed during the reaction it catalyzes.

Which of the following correctly states the relationship between anabolic and catabolic pathways?

Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.

Which of the following cell structures exhibits selective permeability between a cell and its external environment? (Concept 5.1) a. the plasma membrane b. mitochondria c. chloroplasts d. endoplasmic reticulum e. lysosomes

a. the plasma membrane

Which of the following best describes the electron transport chain? (eText Concept 9.4)

Electrons are passed from one carrier to another, releasing a little energy at each step.

Which of the following states the relevance of the first law of thermodynamics to biology?

Energy can be freely transformed among different forms as long as the total energy is conserved.

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

Energy input into the organism must be occurring to drive the decrease in entropy.

Which of the following statements about enzyme function is correct?

Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.

Which of the following statements about enzymes is true?

Enzymes speed up the rate of the reaction without changing the delta G for the reaction.

A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. Which of the following best explains this observation? (eText Concept 9.6)

Fats are better electron donors to oxygen than are sugars.

Under most conditions, the supply of energy by catabolic pathways is regulated by the demand for energy by anabolic pathways. Considering the role of ATP formation and hydrolysis in energy coupling of anabolic and catabolic pathways, which of the following statements is most likely to be true?

High levels of ADP act as an allosteric activator of catabolic pathways

If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, which of the following will result? (eText Concept 9.6)

IDK

Which process is the one in which glucose is oxidized to generate two molecules of pyruvate, and in which ATP and NADH are produced? (eText Concept 9.1)

IDK

If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result? (eText Concept 9.5)

IDK Correct. Muscle cells would not be able to produce enough ATP to meet demands, oxidative phosphorylation would stop, and muscle cells would consume glucose at an increased rate.

When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations?

In the cell, the hydrolysis of ATP is coupled to other endergonic reactions.

Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose? (eText Concept 9.1)

It is converted to heat.

In glycolysis in the absence of oxygen, cells need a way to regenerate which compound? (eText Concept 9.5)

NAD+

the flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme

NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of _____. (eText Concept 9.3)

NADH

What do the sign and magnitude of the delta G of a reaction tell us about the speed of the reaction?

Neither the sign nor the magnitude of delta G have anything to do with the speed of a reaction.

If a compound that allows protons to freely diffuse across membranes is added to cells that are actively metabolizing glucose via cellular respiration, which of the following processes would stop? (eText Concept 9.4)

None of the listed responses is correct.

Which of the following environments or actions would not affect the rate of an enzyme reaction?

None of the listed responses is correct.

Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description?

Organisms acquire energy from one object to another.

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs? (eText Concept 9.3)

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.

Succinylcholine is almost identical to acetylcholine structurally. If succinylcholine is added to a mixture that contains acetylcholine and the enzyme that hydrolyzes acetylcholine (but not succinylcholine), the rate of acetylcholine hydrolysis is decreased. Subsequent addition of more acetylcholine restores the original rate of acetylcholine hydrolysis. Which of the following correctly explains this observation?

Succinylcholine must be a competitive inhibitor with acetylcholine.

Which of the following statements is the best explanation of what happens to the temperature and carbon dioxide concentration during a one-hour class period in a classroom of 300 students if the heating and air conditioning is turned off and all doors are kept closed? (eText Concept 9.1)

Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.

Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. Which of the following would lead to a faster conversion of substrate into product under these saturated conditions?

The first and second listed responses are correct.

Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tends to keep these pathways away from equilibrium?

The first and second listed responses are correct.

Which of the following substances is/are involved in oxidative phosphorylation? (eText Concept 9.4)

The first three listed responses are involved in oxidative phosphorylation.

Which of the following statements about the active site of an enzyme is correct?

The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.

The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs?

The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes? (eText Concept 9.4)

The first two choices are correct.

According to the second law of thermodynamics, which of the following is true?

The decrease in entropy associated with life must be compensated for by increased entropy in the environment in which life exists.

What is meant by the induced fit of an enzyme?

The enzyme changes its shape slightly as the substrate snugly binds to it.

Which of the following statements correctly describe(s) the role(s) of heat in biological reactions?

The first and second choices are correct.

Why is the citric acid cycle called a cycle? (eText Concept 9.3)

The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.

What best characterizes the role of ATP in cellular metabolism?

The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate.

Which of these statements about enzyme inhibitors is true?

The mimic action of competitive inhibitors may be reversible or irreversible.

In glycolysis, there is no production of carbon dioxide as a product of the pathway. Which of the following is the best explanation for this? (eText Concept 9.2)

The products of glycolysis contain the same total number of carbon atoms as in the starting material.

Molecules A and B contain 110 kcal/mol of free energy and molecules C and D contain 150 kcal/mol of energy. A and B are converted to C and D. What can be concluded?

The reaction that proceeds to convert A and B to C and D is endergonic; the products are more organized than the reactants.

When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent this, the tumor can recruit new blood vessels. What purpose does the recruitment of blood vessels to growing tumors serve? (eText Concept 9.4)

The second and third explanations together represent the best answer.

Which of the following statements correctly describes some aspect of ATP hydrolysis being used to drive the active transport of an ion into the cell against the ion's concentration gradient?

This is an example of energy coupling.

Consider the growth of a farmer's crop over a season. Which of the following correctly states a limitation imposed by the first or second law of thermodynamics?

To obey the first law, the crops must represent an open system.

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the membrane would carbohydrates most likely be found? (Concept 5.1) a. on the outside (external) surface of the membrane b. in the interior of the membrane c. on the inside (cytoplasmic) surface of the membrane d. on both hydrophilic surfaces of the membrane but not in the hydrophobic interior e. Carbohydrates are rarely associated with plasma membranes.

a. on the outside (external) surface of the membrane

Which of the following has the most free energy per molecule?

a starch molecule

Which of the following molecules is most likely to passively diffuse across the plasma membrane? (Concept 5.2) a. carbon dioxide b. glucose c. sodium ion d. DNA e. hemoglobin

a. carbon dioxide

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________.

allosteric regulation

When protein molecules are used as fuel for cellular respiration, _____ are produced as waste. (eText Concept 9.6)

amino groups

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes? (eText Concept 9.4)

at the end of the electron transport chain to accept electrons and form H2O

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found? (Concept 5.1) a. on the outside (external) surface of the membrane b. in the interior of the membrane c. on the inside (cytoplasmic) surface d. in the interior and on the inside surface, but not on the outside surface e. on either surface of the membrane, but not in the interior of the membrane

b. in the interior of the membrane

How do enzymes lower activation energy?

by locally concentrating the reactants

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in _____. (eText Concept 9.3)

carbon dioxide

Which is the most abundant form of energy in a cell?

chemical energy

Where do the reactions of glycolysis occur in a eukaryotic cell? (eText Concept 9.1)

cytosol

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? (Concept 5.1) a. Carbohydrates are only found associated with the membranes of prokaryotic cells. b. The carbohydrate composition of most eukaryotic plasma membranes is quite similar. c. Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides. d. Membrane carbohydrates function primarily in cell-cell recognition. e. Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane.

d. Membrane carbohydrates function primarily in cell-cell recognition.

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? (Concept 5.1) a. Phospholipids are completely insoluble in water. b. Phospholipids form a single sheet in water. c. Phospholipids form a structure in which the hydrophobic portion faces outward. d. Phospholipids form a selectively permeable structure. e. They are triacylglycerols, which are commonly available in foods.

d. Phospholipids form a selectively permeable structure.

The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true? (Concept 5.1) a. The fluid aspect of the membrane is due to the behavior of phospholipids, and the mosaic aspect is due to the presence of carbohydrates. b. The fluid aspect of the membrane describes its structure at normal temperatures, and the mosaic aspect describes the behavior of the membrane as the temperature is lowered. c. The mosaic aspect of the membrane is due to the glycosylation of inner leaflet phospholipids. d. The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect. e. Only phospholipids are capable of moving in the membrane.

d. The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.

Which statement(s) about the sidedness of the plasma membrane is/are correct? (Concept 5.1) a. Parts of proteins that are exposed on the cytoplasmic side of the endoplasmic reticulum are also exposed on the cytoplasmic side of the plasma membrane. b. The asymmetrical distribution of membrane proteins, lipids, and carbohydrates across the plasma membrane is determined as the membrane is being constructed. c. Every integral membrane protein has a specific orientation in the plasma membrane. d. The two lipid layers may differ in specific lipid composition. e. All of the listed responses are correct.

e. All of the listed responses are correct.

Which of the following functional processes is not a consequence of the association of proteins with biological membranes? (Concept 5.1) a. enzymatic activity b. cell-cell recognition c. intercellular joining d. cell-cell communication e. energy, carbon, and nitrogen storage

e. energy, carbon, and nitrogen storage

Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? (eText Concept 9.4)

electrons moving down the electron transport chain

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step _____. (eText Concept 9.5)

enables the cell to recycle the reduced NADH to oxidized NAD+

The ability to do work or the capacity to cause change is an example of __________.

energy

The function of cellular respiration is to _____. (eText Concept 9.1)

extract usable energy from glucose

Which of the following represents the major (but not the only) energy accomplishment of the citric acid cycle? (eText Concept 9.3)

formation of NADH and FADH2

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen? (eText Concept 9.3)

four

Of the following molecules in the glycolytic pathway (the process of glycolysis), the one with the most chemical energy is _____. (eText Concept 9.2)

fructose-1,6-bisphosphate

Which of the following reactions would be endergonic?

glucose + fructose → sucrose

In the overall process of glycolysis and cellular respiration, _____ is oxidized and _____ is reduced. (eText Concept 9.1)

glucose ... oxygen

Of the metabolic pathways listed below, which is the only pathway found in all organisms? (eText Concept 9.5)

glycolysis

Enzyme activity is affected by pH because __________.

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site

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 kill bacteria in people with infections. However, he cannot do this because _____. (eText Concept 9.2)

human cells must also perform glycolysis; the drug might also poison them

During respiration in eukaryotic cells, the electron transport chain is located in or on the _____. (eText Concept 9.4)

inner membrane of the mitochondrion

Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds? (eText Concept 9.5)

lactate

A molecule becomes more oxidized when it _____. (eText Concept 9.1)

loses an electron

Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? (eText Concept 9.1)

oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation

Most of the ATP produced in cellular respiration comes from which of the following processes?

oxidative phosphorylation

During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction (eText Concept 9.1)

oxygen

Which of the following functional groups is associated with a release of energy when removed from the carbon skeleton with water that cells can harvest to perform many functions?

phosphate

Which of the following is an example of the cellular work accomplished with the free energy derived from the hydrolysis of ATP, involved in the production of electrochemical gradients?

proton movement against a gradient of protons

The energy given up by electrons as they move through the electron transport chain is used in which of the following processes? (eText Concept 9.4)

pumping H+ across a membrane

Muscle tissues make lactate from pyruvate to do which of the following? (eText Concept 9.5)

regenerate NAD+

Which of the following accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle? (eText Concept 9.3)

release of CO2 and synthesis of NADH

An exergonic (spontaneous) reaction is a chemical reaction that __________.

releases free energy when proceeding in the forward direction

In general, the hydrolysis of ATP drives cellular work by __________.

releasing free energy that can be coupled to other reactions

Which of the following is changed by the presence of an enzyme in a reaction?

the activation energy

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes? (eText Concept 9.3)

the citric acid cycle

Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O2) and produces CO2? (eText Concept 9.4)

the combination of the citric acid cycle and electron transport

Which of the following situations does NOT represent an energy transformation?

the coupling of ATP hydrolysis to the production of a proton gradient across a membrane by a proton pump

The ATP synthase in a human cell obtains energy for synthesizing ATP directly from which of the following processes? (eText Concept 9.4)

the flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme

Which of the following determines the sign of delta G for a reaction?

the free energy of the reactants and the free energy of the products

The formation of glucose-6-phosphate from glucose is an endergonic reaction and is coupled to which of the following reactions or pathways?

the hydrolysis of ATP

Where do the reactions of the citric acid cycle occur in eukaryotic cells? (eText Concept 9.3)

the matrix of the mitochondrion

Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because __________.

the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP

Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that _____. (eText Concept 9.1)

the oxygen atom is very electronegative

A chemical reaction is designated as exergonic rather than endergonic when __________.

the potential energy of the products is less than the potential energy of the reactants

A plot of reaction rate (velocity) against temperature for an enzyme indicates little activity at 10 degrees C and 45 degrees C, with peak activity at 35 degrees C. The most reasonable explanation for the low velocity at 10 degrees C is that ___________.

there is too little activation energy available

A small amount of ATP is made in glycolysis by which of the following processes? (eText Concept 9.1)

transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation

In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle? (eText Concept 9.3)

two ATP, six NADH, two FADH2