Food and Energy

Question 1

What are carbohydrates?

Answer 1

Two types - complex carbohydrates and simple sugars.
Complex carbohydrates include cellulose, glycogen and starch, made up of Simon,e sugar sun-units.
Simple sugars include glucose and lactose.

Question 2

What are proteins?

Answer 2

Long chains of amino acids.
Body digests proteins into amino acids and then assembles amino acids into proteins, e.g. enzymes, haemoglobin, antibodies and hormones.

Question 3

What are fats?

Answer 3

Also known as lipids.
Each fat molecule consists of fatty acids and glycerol.

Question 4

What elements do all biological molecules contain?

Answer 4

Carbon, hydrogen and oxygen.
Amino acids also contain nitrogen.

Question 5

What are then functions of biological molecules in the body?

Answer 5

Simple sugars - fast-release energy source
Complex carbohydrates - structure in cell wall (plants, cellulose), storage molecules (animals, glycogen) and storage molecules (plants, starch).
Fats/lipids - storage molecules.
Proteins - structural role: muscle, functional role: enzymes, haemoglobin.

Question 6

What is the food test for starch?

Answer 6

Name - starch test.
Method - add iodine solution to food.
Positive result - yellow-brown to blue-black.

Question 7

What is the food test for simple sugars?

Answer 7

Name - Benedict’s test.
Method - add Benedict’s solution to food and heat in water bath.
Positive result - blue to green to orange to brick red precipitate.

Question 8

What is the food test for protein?

Answer 8

Name - biuret test.
Method - add sodium hydroxide to food, then add copper sulfate and shake.
Positive result - blue to purple.

Question 9

What is the food test for fats?

Answer 9

Name - ethanol.
Method - mix fat with ethanol to dissolve some of it then add to water.
Positive result - clear to white emulsion.