Membrane Structure and Energy Metabolism

Which statement best describes how cholesterol affects cell membrane fluidity?

• Cholesterol increases fluidity at high temperatures and decreases fluidity at low temperatures.

• Cholesterol increases fluidity at high temperatures and increases fluidity at low temperatures.

• Cholesterol decreases fluidity at high temperatures and decreases fluidity at low temperatures.

• Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures.

Which molecule diffuses through a membrane most quickly?

• Ethylene

• Glucose

• Urea

• Benzene

Glucose typically enters the cell through which mechanism?

• Pinocytosis through a channel protein

• Active transport by a glucose transport protein

• Simple diffusion through the cell membrane

• Facilitated diffusion through a carrier protein

Which statement represents a notable difference between simple diffusion and facilitated diffusion?

• Unlike simple diffusion, facilitated diffusion can transport ligands against a concentration gradient.

• Unlike simple diffusion, the rate of facilitated diffusion is limited by the number of transport proteins in the membrane.

• Unlike simple diffusion, facilitated diffusion requires energy in the form of ATP

• Unlike simple diffusion, facilitated diffusion can occur in any type of cell.

How many molecules of acetyl CoA, an acetyl group attached to ‘coenzyme A’, are produced from a single molecule of glucose for participation in the Krebs cycle?

• 2

• 1

• 3

• 4

How are electrons extracted from the citric acid cycle for use in the electron transport chain? (You can select more than one choice)

• Reduction of NAD+

• Oxidation of NAD+

• Reduction of FAD

• Oxidation of FAD

• Oxidation of ATP

High cellular concentrations of what molecule would inhibit the entry of pyruvate into the citric acid cycle?

• Coenzyme A

• Pyruvate

• AMP

• NADH

Relative to FADH2, at what energy state does NADH enter the electron transport chain?

• NADH enters the electron transport chain at a lower energy state than FADH2

• NADH enters the electron transport chain at a higher energy state than FADH2

• The energy state at which NADH enters the electron transport chain cannot be predicted.

• NADH enters the electron transport chain at the same energy state as FADH2

From where does the reactive oxygen species known as the superoxide anion (O2∙-) originate?

• As a naturally occurring byproduct of multiple body processes

• As a product of superoxide dismutase

• Exogenous (outside the body) sources only

• As a malfunction of the electron transport chain and oxidative phosphorylation

How many total molecules of ATP are synthesized from ADP via glycolysis of a single molecule of glucose?

• 36

• 2

• 4

• 38