Chapter 2 Practice Problems

Question 1

Gram ___________bacteria are characterized by the presence of an outer lipid layer that
contains the molecule, lipopolysaccharide (aka LPS)

A.) Negative
B.) Positive

Answer 1

A.) Negative

Question 2

A yeast cell would be expected to have which of the following cell wall components? (Choose all that apply):

A.) Chitin
B.) Peptidoglycan
C.) N-acetylglucosamine
D.) Cellulose
E.) None of the above

Answer 2

A.) Chitin
C.) N-acetylglucosamine

Question 3

Imagine that a cell was treated with radioactive glucose in which each of the Oxygen atoms
was the isotope 17^O. If this cell undergoes the entire cell respiration process, where would
you expect the 17^O atoms to end up? Explain your answer.

A.) CO2
B.) H2O
C.) O2

Answer 3

A.) CO2
Follow the oxygen atoms in the overall cell respiration equation:
C6H12O6 + 6O2 –> 6 CO2 + 6 H2O

Question 4

At first glance, one might think that cells must continuously violate the 2nd law of
thermodynamics.
Why is this?

Answer 4

One might think this because cells are constantly needing to generate biological order (biosynthesis/anabolic reactions) in a universe that favors disorder.

Question 5

How is it that they do not in fact violate this law, in the grand scheme of things?

Answer 5

In the grand scheme of things, the order-generating reactions that cells utilize collectively
release heat (-due to 1st Law of thermodynamics-) into the surrounding environment, which
increases disorder within that environment.

Question 6

What is the main way in which cells are able to drive nonspontaneous chemical reactions to
occur?

Answer 6

By coupling these reactions to spontaneous ones, such as ATP hydrolysis, such that the
overall free energy change for the coupled reactions is <0.

Question 7

T or F? Explain why if false.
Molecular oxygen is used in glycolysis to oxidize glucose.

Answer 7

FALSE. O2 is used during the oxidative phosphorylation stage of cell respiration where it accepts electrons from complex IV (originating from the oxidation of NADH molecules)

Question 8

T or F? Explain why if false.
The first step of glycolysis involves the transfer of a phosphate to glucose from ATP.

Answer 8

TRUE

Question 9

T or F? Explain why if false.
During glycolysis, ATP is both consumed and generated.

Answer 9

TRUE

Question 10

T or F? Explain why if false.
One molecule of NADH is formed per molecule of glucose oxidized.

Answer 10

FALSE. 10 molecules of NADH are formed per molecule of glucose during aerobic cell respiration. During fermentation, when glucose oxidation produces pyruvate molecules, 2 total NADH are formed.

Question 11

T or F? Explain why if false.
ATP generation during glycolysis comes from the transfer of a phosphate group from a sugar molecule to ADP.

Answer 11

TRUE- this is called substrate-level phosphorylation

Question 12

When electrons flow along the electron transport chains of mitochondria, which of the following
changes occur (choose all that apply)?

A.) The pH of the intermembrane space decreases.
B.) The electrons gain free energy.
C.) The electrons lose free energy.
D.) Oxygen ultimately gets reduced.

Answer 12

A.) The pH of the intermembrane space decreases.
C.) The electrons lose free energy.

Question 13

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

A.) Some amino acids can bypass glycolysis and enter the Citric Acid cycle.

Answer 13

TRUE

Question 14

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

B. Fatty acids must first undergo deamination prior to being oxidized.

Answer 14

FALSE

Question 15

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

C. Triglycerides are first broken down into glycerol and fatty acids

Answer 15

TRUE

Question 16

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

D. Fats contain a little over double the amount of energy (in calories/gram) than that of
sugars.

Answer 16

TRUE

Question 17

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

E. Deamination of amino acids generates urea, which is converted to ammonia in the liver.

Answer 17

FALSE

Question 18

While glucose is the preferred energy source for all cells, cells are able to extract energy from
proteins and lipids as well. Write ‘T’ or ‘F’

F. Glycerol can enter the Citric acid cycle following attachment to CoA.

Answer 18

FALSE

Question 19

When might a person’s metabolism switch into Ketogenesis, and what is the goal of this form of
metabolism?

Answer 19

Ketogenesis happens during prolonged fasting periods (over 24 hours), once liver glycogen
stores are depleted. The goal of ketogenesis is to supply the body with ketones as an
alternative to glucose. The brain requires a constant supply of energy and can use ketones if
glucose is not available. Also, a diet that is very low in carbohydrates (without too much
protein) can also cause induce ketogenesis.

Question 20

When might a person’s metabolism rely mostly/solely upon amino acids as an energy source?

Answer 20

A low fat, low carbohydrate diet could cause the body to metabolize amino acids.

Question 21

About 8 hours after you eat a meal containing carbs, proteins, and fats, what is the primary
source of glucose used to maintain your blood glucose levels?

A.) The carbohydrates from your meal
B.) Glucose produced by gluconeogenesis in liver
C.) Glucose produced by glycogenolysis in muscle
D.) Glucose produced by glycogenolysis in liver

Answer 21

D.) Glucose produced by glycogenolysis in liver

Question 22

About 8 hours after you eat a meal containing carbs, proteins, and fats, what is the primary
means of ATP generation?

A.) Glucose oxidation (beginning from glycolysis)
B.) Fatty acid oxidation
C.) Ketone oxidation

Answer 22

B.) Fatty acid oxidation

Question 23

When you consume a meal, and blood glucose levels are high, the pancreas secretes the
hormone, insulin. Which of the following would be inhibited by insulin? Choose all that apply.
Justify your answer.

A.) Glucose uptake into muscle cells
B.) Lipolysis in adipocytes
C.) Storage of excess glucose in liver via glycogen synthesis
D.) Gluconeogenesis in hepatocytes

Answer 23

B.) Lipolysis in adipocytes
D.) Gluconeogenesis in hepatocytes

Insulin promotes glucose uptake, storage, and utilization. It will act to inhibit the
synthesis of additional glucose, and would promote lipid storage over lipolysis.

Question 24

Metabolic syndrome is a cluster of physiological abnormalities including:

A.) elevated blood glucose levels
B.) elevated lipid levels
C.) insulin resistance
D.) obesity
E.) All of the above.

Answer 24

E.) All of the above.

Question 25

Individuals suffering from Type II Diabetes tend to initially make sufficient amounts of insulin but yet have abnormally high blood glucose levels. Why is this?

Answer 25

Cells in individuals with Type II diabetes are insulin resistant, which means that they are unable
to respond to insulin binding. As a result, glucose transporters are not signaled to reach the cell
membrane, and glucose does not enter the cell, leaving elevated glucose levels in the blood.

Question 26

How can obesity lead to insulin resistance? Be sure to use the terms ‘free fatty acids’ and
‘lipolysis’ in your answer.

Answer 26

An excess of lipids in adipocytes increases lipolysis, which releases free fatty acids (FFAs) into
the blood where they are taken up by other tissues. These FFAs can interfere with insulin
receptor function, preventing the receptor from signaling glucose transporters to reach the cell
membrane to allow glucose entry. The result: insulin resistance