Unit 2.c: Biological Molecules

Question 1

Carbohydrates

Answer 1

They contain oxygen, carbon, hydrogen. They supply cells with energy. Glucose is the product from digestion.
- lactose → milk,
- fructose → fruits,
- sucrose → table sugar

Question 2

Different types of carbohydrates

Answer 2

• Starch is a large, insoluble molecule which is stored in plants,
• Glycogen is an energy store,
• Cellulose is the material of cell walls (which humans can’t digest). It’s also a dietary fibre

Question 3

Proteins

Answer 3

They contain oxygen, carbon, hydrogen + nitrogen.
They are used for growth and repair.
Amino acids are a product of digestion.
Enzymes are also made of protein.

Question 4

Lipids (fats)

Answer 4

They contain oxygen, carbon, hydrogen. They are used for insulation and energy. 3 fatty acids and glycerol are products of digestion. They protect organs from damage.

Question 5

Food tests and positive results.

Answer 5

• Carbohydrates = iodine, orange → black,
• Protein = Biuret solution, blue → purple,
• Glucose = Benedict’s solution + hot water bath, blue/green → orange/red,
• Lipids = ethanol + water, clear → cloudy