B3.3 Food Tests And The Chemistry Of Food

Question 1

What chemical is used to test for starch?

Answer 1

Iodine

Question 2

What chemical is used to test sugar?

Answer 2

Benedicts solution

Question 3

What is the chemical used to test for lipids (fats)?

Answer 3

Ethanol

Question 4

What chemical is used to test for proteins?

Answer 4

Biuret solution

Question 5

What colour is iodene and what colour does it turn into when starch is present?

Answer 5

Orange-red —> blue black

Question 6

What colour is benedicts solution and what colour does it turn into when sugar is present?

Answer 6

Light blue —> green (if less sugar) to brick red (if alot sugar)

Question 7

What colour is ethanol and what colour does it turn into when lipids are present?

Answer 7

Colourless —> cloudy emulsion

Question 8

What colour is biuret and what colour does it turn into when protein is present?

Answer 8

Blue —> lilac purple

Question 9

How would you prepare the food samples before a food test?

Answer 9

• Break up the food using a pestle and mortar
• Transfer to a test tube and add distilled water
• Mix the food with the water by stirring with a glass rod
• Filter the mixture using a funnel and filter paper, collecting the solution

Question 10

Explain how to use benedicts solution to find out if sugar is present

Answer 10

Add a couple drops if benedicts solution to your pre-prepared sugary solution and put the test tube in hot water(anout 80 degrees) for 5 min. Then check for any colour changes.

Question 11

What are proteins made up of?

Answer 11

Long chains of differents amino acids

Question 12

Why are proteins needed in the body?

Answer 12

• Proteins are needed in the diet for growth and repair of body tissues (e.g. bone ,muscle etc).

Question 13

What are the three different types of carbohydrates?

Answer 13

• Sugar
• Starch
• Fibre

Question 14

What enzyme breaks up large starch molecules and what does it produce?

Answer 14

Carbohydrase breaks down large starch molecules to produce sugar molecules.

Question 15

What enzyme breaks up protein molecules?

Answer 15

Protease breaks down protein molecules to produce amino acid moleculesm

Question 16

What are fats/lipids made of (structure)

Answer 16

They are made up of a glycerol molecule joined to three fatty acids.

Question 17

What are fats for in our body?

Answer 17

Fats provide energy and insulation for the body.

Question 18

Where are fats stored?

Answer 18

They are stored under the skin and around the organs as adipose tissue.

Question 19

What enzyme digest fatty/lipid molecules and into what?

Answer 19

Lipase breaks down lipid molecules into fatty acid molecules and glycerol molecules.

Question 20

What is amylase an example of?

Answer 20

Amylase is an example of a carbohydrase enzyme.

Question 21

Where is amylase stored?

Answer 21

Mouth and small intestine.

Question 22

Where is protease stored?

Answer 22

Stomach, small intestine

Question 23

Where is lipase stored?

Answer 23

Small intestine

Question 24

What does fibre do for us?

Answer 24

Aids digestion and prevents constipation.

Question 25

Why do we need carbohydrates?

Answer 25

Good for providing energy

Question 26

What can high cholosterol lead to?

Answer 26

Can lead to narrowing the arteries - corinary heart disease - stroke
- need for stent
- need to take statins