Biological Molecules And Diet

Question 1

What are carbohydrates made of?

Answer 1

Carbon, hydrogen, oxygen

Question 2

What are cats (lipids) made up of?

Answer 2

Carbon, hydrogen, oxygen
3 fatty acids joined to a glycerol molecule

Question 3

What are proteins made of?

Answer 3

Carbon, hydrogen, oxygen, nitrogen
Many amino acids joined together

Question 4

What is the test for glucose?

Answer 4

Benedict’s solution

Question 5

Describe the method for the test for glucoses

Answer 5

Add Benedict’s solution to a sample of food
Place in water bath at 80°C for 5 minutes
If a reducing sugar is present the colour will change from blue to brick red

Question 6

What is the test for starch

Answer 6

Iodine test

Question 7

Describe the method for the test for starch.

Answer 7

Add a few drops of orange iodine solution to the sample on a spotting tile
A blue black colour indicates presence of starch

Question 8

What is the test for protein?

Answer 8

Biuret test

Question 9

Describe the method for the test for protein.

Answer 9

Add 2cm3 water to a food sample and shake
Add an equal volume of dilute potassium hydroxide and shake
Add two drops of 1% copper sulfate solution
If protein is present then a pale purple colour will develop

Question 10

What is the test for lipids?

Answer 10

Emulsion

Question 11

Describe the method for the test for lipids.

Answer 11

Place food sample in a test tube
Add a small volume of absolute ethanol and shake to dissolve any lipid in the alcohol
Add an equal volume of water
A cloudy white colour indicates the presence of lipid