DBB11402 Carbohydrate Metabolism Quiz

What is the primary function of glycolysis?

• To produce glucose from non-carbohydrate sources

• To synthesize glycogen

• To convert glucose into pyruvate

• To transport glucose across cell membranes

Answer explanation

The primary function of glycolysis is to convert glucose into pyruvate, which is a key step in cellular respiration, allowing for energy production in the form of ATP.

Which pathway is responsible for the conversion of pyruvate to glucose?

• Glycolysis

• Glycogenesis

• Gluconeogenesis

• Fermentation

Answer explanation

Gluconeogenesis is the metabolic pathway that converts pyruvate into glucose, primarily occurring in the liver. Glycolysis breaks down glucose, glycogenesis stores glucose as glycogen, and fermentation is an anaerobic process.

What is the role of GLUT 4 transporters?

• Transport glucose in the liver

• Transport glucose in adipose and muscle tissues

• Transport fructose in the intestine

• Transport glucose in the brain

Answer explanation

GLUT4 transporters are primarily responsible for transporting glucose into adipose (fat) and muscle tissues in response to insulin, facilitating glucose uptake for energy and storage.

Which of the following is a product of the Krebs cycle?

• Lactate

• Glucose

• Fructose

• NADH

Answer explanation

NADH is a key product of the Krebs cycle, which is involved in cellular respiration. The other options, lactate, glucose, and fructose, are not direct products of this cycle.

What is the main purpose of the pentose phosphate pathway?

• Generate ATP

• Synthesize glycogen

• Produce NADPH and ribose precursors

• Convert glucose to pyruvate

Answer explanation

The main purpose of the pentose phosphate pathway is to produce NADPH, which is essential for biosynthetic reactions, and ribose-5-phosphate, a precursor for nucleotide synthesis, making 'Produce NADPH and ribose precursors' the correct choice.

What is the primary energy source for the brain?

• Fatty acids

• Glucose

• Amino acids

• Ketones

Answer explanation

The brain primarily uses glucose as its main energy source. While it can utilize ketones during prolonged fasting, glucose is the preferred and most efficient fuel for normal brain function.

Which of the following is NOT a mechanism of monosaccharide absorption?

• Passive diffusion

• Osmosis

• Active transport

• Facilitated diffusion

Answer explanation

Osmosis is the movement of water across a membrane, not a mechanism for monosaccharide absorption. Monosaccharides are absorbed via passive diffusion, active transport, and facilitated diffusion.

What is the function of glycogen phosphorylase?

• Break down glycogen

• Convert glucose to pyruvate

• Synthesize glycogen

• Transport glucose into cells

Answer explanation

Glycogen phosphorylase is an enzyme that catalyzes the breakdown of glycogen into glucose-1-phosphate, making 'break down glycogen' the correct function. The other options involve different metabolic processes.

What is the role of insulin in carbohydrate metabolism?

• Promotes glucose uptake

• Stimulates glycogenolysis

• Inhibits glycolysis

• Promotes gluconeogenesis

Answer explanation

Insulin promotes glucose uptake by cells, facilitating the use of glucose for energy. This is crucial in carbohydrate metabolism, while the other options either describe processes that insulin inhibits or does not stimulate.

Which of the following is a key regulatory enzyme in glycolysis?

• Phosphofructokinase-1

• Fructose bisphosphatase

• Lactate dehydrogenase

• Glycogen synthase

Answer explanation

Phosphofructokinase-1 is a key regulatory enzyme in glycolysis, controlling the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. The other options are not involved in glycolysis regulation.