Biological molecules

Which element is NOT a component of carbohydrates?

• a) Carbon
• b) Hydrogen
• c) Oxygen
• d) Nitrogen

The primary storage form of carbohydrates in animals is:

• a) Starch
• b) Glycogen
• c) Cellulose
• d) Sucrose

Why is glucose stored as glycogen in animals?

• a) Glycogen is soluble and readily available for use
• b) Glycogen does not cause osmotic effects in cells
• c) Glycogen provides structural support to cells
• d) Glycogen is involved in photosynthesis

Which carbohydrate forms the structural component of plant cell walls?

• a) Starch
• b) Glucose
• c) Cellulose
• d) Glycogen

The iodine test turns blue-black in the presence of:

• a) Reducing sugars
• b) Lipids
• c) Starch
• d) Proteins

Proteins are composed of:

• a) Monosaccharides
• b) Fatty acids and glycerol
• c) Amino acids
• d) Nucleotides

Which element is unique to proteins and not found in carbohydrates or lipids?

• a) Hydrogen
• b) Oxygen
• c) Nitrogen
• d) Carbon

What happens during the Biuret test if protein is present?

• a) The solution turns red
• b) A purple color appears
• c) The solution turns cloudy
• d) The solution remains clear

Keratin, a protein, is primarily found in:

• a) Muscle fibers
• b) Liver cells
• c) Hair and nails
• d) Blood plasma

What is the role of sulfur in proteins?

• a) It forms the carbohydrate backbone
• b) It provides energy to cells
• c) It creates cross-linkages in polypeptide chains
• d) It acts as a coenzyme for biochemical reactions