(c) Biological molecules

Question 1

What chemical elements are there in Carbohydrates?

Answer 1

(CHO) Carbon, Hydrogen, Oxygen

Question 2

What is the monomer of Carbs? Give an example

Answer 2

The monomer is monosaccharide, and glucose is a type of monosacchride

Question 3

What happens when 2 glucose are joined together? Give an example

Answer 3

They form a disaccharide, e.g maltose

Question 4

What happens when lots of glucose are joined together? Give some examples

Answer 4

They form a polysaccharide, e,g starch, glycogen, cellulose, chitin

Question 5

What is the function of Carbs?

Answer 5

Important source of Fast energy

Question 6

Examples of food high in Carbs?

Answer 6

Pasta, breads

Question 7

How to test for Starch?

Answer 7

Add drops of Iodine to the food sample; positive: from blue to blue-black, negative: yellow/orange

Question 8

What is reducing sugar? Give some examples

Answer 8

Monosacchride such as glucose, and some disaccharide such as maltose are reducing sugar. They reduce other compounds such as the Benedict’s solution.

Question 9

How to test for reducing agent such as glucose?

Answer 9

You add Benedict’s solution (mixture of sodium carbonate, sodium citrate, copper (II) sulphate pentahydrate) and heat it at 80 °C for 5 minutes; positive: from blue to brick red, negative: remains blue (the colour of the precipitate depends on the concentration of reducing sugar, 0g% is blue and high in glucose >2g% is brick red)

Question 10

How do you test for Starch (a polysaccaride)?

Answer 10

You add drops of Iodine to the food sample,; positive: brown to blue-black, negatie: yellow/orange

Question 11

What chemical elements are there in Lipids?

Answer 11

(CHO) Carbon, Hydrogen, Oxygen

Question 12

What is the structure of Lipids and what the are the 2 types of its monomers?

Answer 12

It has triglyceride structure and is made up of 3 fatty acids chains (vary in size & structure) and 1 glycerol molecule

Question 13

What 2 groups are Lipids devided into? What are the differences between them?

Answer 13

Saturated and Unsaturated. Saturated are Fats and are solid at r.t. They form only Carbon-Carbon single bond. Unsaturated are Oils, and are liquid at r.t. They form both Carbon-Carbon single bond and double bonds.

Question 14

Is saturated lipid better or unsaturated fat better? Why?

Answer 14

Unsaturated lipids are better, because they include polyunsaturated fatty acids & monounstructured fats. They can help lower the cholesterol levels (cholesterol cannot be exercised off, it is only found in animal products & high-fat dairy products) and reduce the risk of hear diseases.

Question 15

Examples of food high in lipids?

Answer 15

Butter, oil and cholesterol

Question 16

How do you test for Lipids?

Answer 16

It is called the Emulsion test. You mix the food sample with 2 cm3 of ethanol and shake, the ethanol is added to an equal volume of cold water; positive: white, cloudy will emerge

Question 17

What chemical elements are there in Proteins?

Answer 17

CHON: Carbon, Hydrogen, Oxygen, Nytrogen, and some contain Sulphur

Question 18

What is the structure of Protein and what the is its monomers?

Answer 18

The monomer is Amino acids, and they join together to form a long chain called polypoptide

Question 19

What are the functions of Proteins?

Answer 19

Muscle development, work in immune system, make up enzymes, genes are codes for proteins

Question 20

How to test for Proteins?

Answer 20

You use Biuret reagent (sodium hydroxide and copper sulphate). Add drops of it to the food sample; positive: blue to purple, negative: remains blue