[7] Cellular Respiration and Fermentation - Practice Questions

Question 1

A molecule becomes more oxidized when it ___.

Answer 1

loses an electron

Question 2

In the overall process of glycolysis and cellular respiration, ___ is oxidized, while ___ is reduced.

Answer 2

…glucose is oxidized, while oxygen is reduced

Question 3

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

a) glycolysis
b) oxidative phosphorylation
c) the citric acid cycle
d) substrate-level phosphorylation
e) reduction of NADH

Answer 3

b) oxidative phosphorylation

Question 4

Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration?

a) oxidation of pyruvate; citric acid cycle; oxidation of glucose to pyruvate; oxidative phosphorylation
b) glycolysis; reduction of pyruvate; citric acid cycle; oxidative phosphorylation
c) glycolysis; oxidative phosphorylation; citric acid cycle; oxidation of pyruvate.
d) oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation
e) oxidation of glucose to pyruvate; reduction of pyruvate; citric acid cycle; oxidative phosphorylation

Answer 4

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

Question 5

The function of cellular respiration is to ___.

Answer 5

harvest usable energy from glucose

Question 6

During the reaction below, which compound is reduced as a result of the reaction?

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O

Answer 6

oxygen

Question 7

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?

Answer 7

It is converted to heat.

Question 8

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?

a) Temperature goes up and the level of carbon dioxide goes down. This is because cellular respiration is an exergonic process that is only about 38% efficient; the remaining energy is lost to the environment as heat. Also, carbon dioxide is being converted to organic molecules such as fats and sugars during cellular respiration.
b) Neither temperature nor carbon dioxide levels change because cellular respiration is 100% efficient and because carbon dioxide produced by cellular respiration is just as rapidly consumed by cellular respiration.
c) Temperature goes up but carbon dioxide levels remain constant because heat is a by-product of cellular respiration but carbon dioxide is converted to sugar during cellular respiration.
d) Temperature goes down and carbon dioxide levels remain constant. This is because cellular respiration, being an endergonic reaction, requires an input of heat energy from the environment to occur and because carbon dioxide is neither produced nor consumed by cellular respiration.
e) Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.

Answer 8

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

Question 9

Where do the reactions of glycolysis occur in a eukaryotic cell?

Answer 9

the cytosol

Question 10

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

Answer 10

glycolysis

Question 11

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?

a) Glucose contains more carbons than the number of carbons found in the pyruvate products that are produced by glycolysis.
b) There is very little ATP produced in glycolysis.
c) The initial steps of glycolysis require an input of energy in the form of ATP (two per glucose).
d) There are no oxidation or reduction reactions in glycolysis to produce CO₂.
e) The products of glycolysis contain the same total number of carbon atoms as in the starting material.

Answer 11

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

Question 12

Most of the NADH that delivers electrons to the electron transport chain comes from which process?

Answer 12

the citric acid cycle

Question 13

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 __________.

Answer 13

carbon dioxide

One molecule of CO₂ is formed when pyruvate is converted to acetyl CoA, and two molecules of CO₂ are produced in the citric acid cycle.

Question 14

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?

a) Pyruvate is ionized directly to acetyl-coA.
b) Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH.
c) Pyruvate is oxidized and decarboxylated, and the resulting electrons are donated to NADH to produce NAD⁺.
d) Pyruvate is reduced and decarboxylated, and the resulting electrons oxidize an NAD⁺ to an NADH
e) Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD⁺ to an NADH.

Answer 14

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

Question 15

Why is the citric acid cycle called a cycle?

Answer 15

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.

Question 16

Where do the reactions of the citric acid cycle occur in eukaryotic cells?

Answer 16

the matrix of the mitochondrion

Question 17

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?

Answer 17

four

Question 18

Which process represents the major energy accomplishment of the citric acid cycle?

Answer 18

formation of NADH and FADH_²

Question 19

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________.

Answer 19

NADH

Question 20

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

Answer 20

the combination of the citric acid cycle and electron transport

Question 21

What is the purpose of molecular oxygen (O2) during aerobic respiration?

Answer 21

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

Question 22

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?

a) glycolysis
b) ATP synthesis
c) electron transport
d) All of the above.
e) None of the above.

Answer 22

e) None of the above.

Question 23

Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria?

a) the components of the electron transport chain
b) electrons moving down the electron transport chain
c) the production of NADH
d) ATP
e) an ATP-dependent proton pump

Answer 23

b) electrons moving down the electron transport chain

Question 24

During respiration in eukaryotic cells, the electron transport chain is located in or on the __________.

Answer 24

inner membrane of the mitochondrion

Question 25

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.

Answer 25

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

Question 26

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 compounds?

Answer 26

lactate

Question 27

In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?

Answer 27

NAD+

Question 28

Muscle tissues make lactate from pyruvate to do what?

Answer 28

regenerate NAD⁺

Question 29

If muscle cells in the human body consume O₂ faster than it can be supplied, what is likely to result?

Answer 29

The muscle cells will have more trouble making enough ATP to meet their energy requirements. The cells will not be able to carry out oxidative phosphorylation. The cells will consume glucose at an increased rate.

Question 30

What metabolic pathway discussed in cellular respiration is the only pathway found in all organisms?

Answer 30

glycolysis

Question 31

When protein molecules are used as fuel for cellular respiration, __________ are produced as waste.

Answer 31

amino groups