Question 1

Which of the following best describes the difference between primary and secondary active transport across a cell membrane?

Accepted Answer

Primary active transport uses ATP directly to move molecules against their concentration gradient, while secondary active transport uses the energy stored in an ion gradient created by primary active transport.

Question 2

A patient is experiencing muscle fatigue after intense exercise. Which metabolic pathway is responsible for recycling lactate produced in the muscles, and what is the main organ involved?

Accepted Answer

The Cori Cycle, with the liver converting lactate back to glucose.

Question 3

Which of the following is TRUE regarding the regulation of glycogen synthase and glycogen phosphorylase by insulin and glucagon?

Accepted Answer

Insulin activates glycogen synthase and inactivates glycogen phosphorylase by promoting dephosphorylation.

Question 4

Which of the following best describes the main function of the pentose phosphate pathway?

Accepted Answer

To generate NADPH for anabolic reactions and provide ribose-5-phosphate for nucleotide synthesis.

Question 5

Which of the following cell types is NOT responsive to glucagon?

Accepted Answer

Skeletal muscle cells

Question 6

Which of the following statements about glycerophospholipids is CORRECT?

Accepted Answer

They contain a phosphate polar head group on C3, a saturated acyl chain on C1, and a monounsaturated acyl chain on C2 of the glycerol backbone.

Question 7

Which enzyme catalyzes the conversion of pyruvate to lactate, and what is the cofactor involved?

Accepted Answer

Lactate dehydrogenase; NADH

Question 8

Which of the following best describes the difference between Hexokinase 1 and Hexokinase 4?

Accepted Answer

Hexokinase 1 is found in all tissues and is active at low glucose concentrations, while Hexokinase 4 is found in the liver and pancreas and is active at high glucose concentrations.

Question 9

Which of the following is a correct sequence of events in a G protein-coupled receptor (GPCR) signal transduction pathway?

Accepted Answer

First messenger binds receptor → G protein (transducer) activated → Effector enzyme activated → Second messenger produced

Question 10

Which of the following best describes the role of phosphorylation in the regulation of glycogen metabolism?

Accepted Answer

Phosphorylation activates glycogen phosphorylase and inactivates glycogen synthase.

Question 11

A patient with a deficiency in the pentose phosphate pathway would most likely have problems with which of the following?

Accepted Answer

Generating NADPH for fatty acid synthesis and maintaining reduced glutathione.

Question 12

Which of the following best describes the function of a symporter in membrane transport?

Accepted Answer

It transports two different molecules in the same direction across the membrane.

Question 13

Which of the following is a product of the pentose phosphate pathway that can be used for nucleotide synthesis?

Accepted Answer

Ribose-5-phosphate

Question 14

Which of the following best explains why insulin promotes glycogen synthesis after a meal?

Accepted Answer

Insulin is released in response to high blood glucose and activates glycogen synthase, promoting storage of excess glucose as glycogen.

Question 15

Which of the following is NOT a use for the sugars generated by the pentose phosphate pathway?

Accepted Answer

Direct conversion to fatty acids

Question 16

Which of the following best describes the fate of lactate produced during anaerobic glycolysis in muscle cells?

Accepted Answer

It is transported to the liver, where it is converted back to glucose via gluconeogenesis (Cori Cycle).

Question 17

Which of the following is a correct description of the omega-3 bond in docosapentaenoic acid (DPA, 22:5, Δ7,10,13,16,19)?

Accepted Answer

The omega-3 bond is the third double bond from the methyl (omega) end of the fatty acid.

Biochemistry Exam 3 Review: Membrane Transport, Signal Transduction, Metabolic Regulation, and Key Pathways

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