B3.1 . BIOLOGICAL MOLECULES

Question 1

What are the basic unit of Lipids

Answer 1

fatty acids and glycerol

Question 2

What are the basic unit of Carbohydrates

Answer 2

simple sugars

Question 3

What are the basic unit of proteins

Answer 3

amino acids

Question 4

give two differences between the structure of a protein and a carbohydrate.

Answer 4

1. Protein formed from amino acids, carbohydrates from simple sugars.
2. Carbohydrates are often made from one kind of simple sugar, protein from many different kinds of amino acids.

Question 5

Why water is essential for living organism?

Answer 5

because many substances dissolve in it.

because forms the basis of cell cytoplasm (where many reactions occur).

Question 6

Describe what you would see if you tested samples of Glucose syrup with

i) Benedict’s solution
ii) iodine solution: (explain your answer)

Answer 6

i) Benedict’s solution
An ORANGE-RED precipitate would form, because glucose is reducing sugar.

ii) Iodine solution
The solution wouldn’t change colour as there is no starch present.

Question 7

Describe what you would see if you tested samples of A cake made with wheat flour, table sugar (sucrose), fat and eggs with

i) Benedict’s solution
ii) iodine solution: (explain your answer)

Answer 7

i) Benedict’s solution
There would be no changes in colour because sucrose and starch in wheat flour are not glucose (reducing sugar).

ii) Iodine solution
The solution would turn BLUE-BLACK because of the starch in the flour.

Question 8

Explain how you would test the seed from a walnut tree to see if it contained stores of FAT

Answer 8

Crush the walnut using a mortar and pestle then
mix part with ETHANOL,
decant the liquid and add water,
if the mixture turn cloudy, then fat is present.

Question 9

Explain how you would test the seed from a walnut tree to see if it contained stores of PROTEIN

Answer 9

Crush the walnut using a mortar and pestle then
Mix part with water to form a solution,
Add a few drop of BIURET solution,
If protein present, a blue ring forms at the surface, which disappears to form a purple solution.

Question 10

proteins are made of…….

Answer 10

amino acids molecules

Question 11

fats and oils are made of…….

Answer 11

fatty acids and glycerol molecules

Question 12

carbohydrates are made of…….

Answer 12

glucose molecules