Biosystems 2 Review 1

What glucose monomers make up lactose?

• Glucose - Galactose

• Glucose - Glucose

• Glucose - Fructose

• Fructose - Galactose

Answer explanation

Lactose is made up of glucose and galactose monomers. The correct choice is Glucose - Galactose. What is the name and composition of the two other dimers of glucose?

Which enzyme is used first at the start of glycolysis and some glycogenesis? (Choose BEST answer)

• phosphoglycerate kinase

• glucokinase

• phosphofructokinase

• hexokinase

Answer explanation

Hexokinase is the first enzyme used in glycolysis and glycogenesis. It starts the use of glucose by converting it to glucose-6-phosphate, initiating these pathways. Glucokinase is the other enzyme used in glycogenesis but isn't used in glycolysis. In which parts of the body are each of these glycogenesis enzymes found?

Hexokinase is inhibited by what product?

• pyruvate

• glucose 6 phosphate (G6P)

• lactic acid

• glycogen

Answer explanation

Hexokinase is inhibited by G6P which is why glycokinase is used to make most of the glycogon in the body during glycogenesis.

Which glycolysis enzyme is directly affected by concentrations of ATP? (Choose BEST answer)

• Phosphofructokinase

• Pyruvate kinase

• Hexokinase

• Phosphoglycerate kinase

Answer explanation

Although all the activity of these enzymes can be affected by the products of glycolysis/TCA/ETC the best answer is phosphoglycerate kinase because it's product (ATP).

Which enzyme commits glucose to glycolysis? (Choose BEST answer)

• Hexokinase

• phosphofructokinase (PFK2)

• phosphofructokinase (PFK1)

• pyruvate kinase

Answer explanation

The enzyme that commits glucose to glycolysis is phosphofructokinase (PFK1). PFK2 isn't the best answer because it activates the ability of PFK1 to commit to glycolysis. Hexokinase only commits to using glucose but can then take two other paths.

What are some functions of the liver? (SATA)

• Storing glycogen

• Choosing metabolism pathway

• Activating prodrugs

• Maintaining osmolarity of the blood

Answer explanation

Two answers are from the metabolism unit as pure definition. The third was a throwback question and the fourth option was a trick because that is the function of the kidney.

What enzyme is used in the final step of glycolysis converting PEP to pyruvate?

• Pyruvate kinase

• Pyruvate dehydrogenase

• Pyruvate carboxylase

• Pyruvate decarboxylase

Answer explanation

Pyruvate kinase is the correct answer for formation of pyruvate. The other three enzymes use pyruvate.

Catabolic is... (SATA)

• Nonspontaneous

• Spontaneous

• -delta G

• Exergonic

Answer explanation

Anabolic is nonspontaneous, endergonic, and has +delta G.

Large molecules have...

• Less potential energy

• More potential energy

• No energy

• More kinetic energy

Answer explanation

This concept applies to when we think about catabolic vs. anabolic potential energies.

Which paired term is correctly matched?

• Riboflavin - NAD+/NADH

• Vitamin B2 - Niacin

• Vitamin B3 - Riboflavin

• Vitamin B3 - NAD+/NADH

Answer explanation

FAD/FADH2 are derived from riboflavin (Vitamin B2). NAD+/NADH are derived from niacin (Vitamin B3).