Carbohydrate Structures and Functions in Living Organisms

Carbohydrates are essential biomolecules composed of carbon, hydrogen, and oxygen. They serve as energy sources and structural components in organisms. Carbohydrates are made of monosaccharides, which can form disaccharides and polysaccharides. Digestion breaks carbohydrates into simple sugars for absorption. Glucose is central to energy production, undergoing glycolysis and other metabolic pathways. Fructose metabolism differs as it bypasses some regulatory steps, leading to unregulated conversion to fats.

What is the basic structural unit of carbohydrates?

• Oligosaccharides

• Polysaccharides

• Monosaccharides

• Disaccharides

Which of the following is a disaccharide?

• Glucose

• Fructose

• Cellulose

• Sucrose

What type of linkage is found in cellulose?

• Alpha-linkages

• Beta-linkages

• Gamma-linkages

• Delta-linkages

Which enzyme initiates the digestion of starch?

• Sucrase

• Amylase

• Lactase

• Maltase

What is the primary role of dietary fibers?

• Enhance protein synthesis

• Increase blood glucose levels

• Slow digestion and add bulk to stool

• Provide energy

What is the first step in glucose metabolism?

• Citric acid cycle

• Gluconeogenesis

• Glycolysis

• Electron transport chain

In the absence of oxygen, what is pyruvate converted into?

• Fructose

• Acetyl-CoA

• Lactate

• Glucose

What process synthesizes new glucose when glycogen is depleted?

• Gluconeogenesis

• Glycolysis

• Fermentation

• Photosynthesis

How does fructose enter the glycolytic pathway?

• At the beginning of glycolysis

• Through the citric acid cycle

• At the level of 3-carbon intermediate

• Directly as glucose

What happens to acetyl-CoA when it is present in excess?

• It is converted into fatty acids

• It is used in protein synthesis

• It is stored as glycogen

• It is converted into glucose