Nutrients

Question 1

What are the 6 basic nutrients that are essential for the healthy functioning of our bodies?

Answer 1

• Carbohydrates
• Proteins
• Fats
• Minerals
• Vitamins
• Water

Question 2

What are the roles of water in humans?

Answer 2

Water:

• is the solvent in which chemical reactions take place.
• is an essential component of cells, tissues, digestive juices and blood.
• helps to control body temperature through sweating.
• helps to transport dissolved substances around the body.

Question 3

What are the roles of water in plants?

Answer 3

Water is needed for:

• Photosynthesis.
• Keeping the plant cells turgid and plants upright.
• Transport of dissolved mineral salts up the xylem.
• Transport of dissolved food substances from the leaves to other parts of the plant.

Question 4

List the chemical elements which make up carbohydrates, fats and proteins respectively.

Answer 4

Carbohydrates are made up of carbon, hydrogen and oxygen. Fats are made up of carbon, hydrogen and oxygen. Proteins are made up of carbon, hydrogen, oxygen and nitrogen. (Note that sulfur may be present in some proteins as well.)

Question 5

Describe how the test for starch is carried out.

Answer 5

The iodine test can be carried out to test for the presence of starch.
1. Add 2cm^3 of food sample to a clean test tube.
2. Add a few drops of iodine solution to the test tube.
3. (-) The solution remains yellowish-brown.
(+) Blue-black solution is formed.

Question 6

Describe how the test for reducing sugars is carried out.

Answer 6

The Benedict’s test can be carried out to test for the presence of reducing sugars.
1. Add 2cm^3 of Benedict’s solution to 2cm^3 of food sample in a test tube.
2. Shake the mixture.
3. Heat the contents in a boiling water bath for 2-3mins.
4. Solution remained blue: No reducing sugar present.
Blue to green ppt formed: Traces of reducing sugar present.
Blue to yellow or orange ppt: Moderate amount of reducing sugar.
Blue to brick-red ppt: Large amount of reducing sugar present.

Question 7

Describe how the test for proteins is carried out.

Answer 7

The Biuret test can be carried out to test for the presence of proteins.
1. Add 2cm^3 of Biuret solution to 2cm^3 of food sample into a test tube.
2. Shake the mixture thoroughly.
3. Wait for a few minutes.
4. (-) The solution remains blue if proteins are absent.
(+) Purple or violet solution is formed if proteins are present.

Question 8

Describe how the test for fats is carried out.

Answer 8

The ethanol emulsion test can be carried out to test for the presence of fats.
1. Add 2cm^3 of ethanol to 2cm^3 of food sample in a test tube.
2. Shake the contents of the tube vigorously.
3. Decant 3cm^3 of water into the test tube and shake the mixture.
4. (-) The solution remains clear if fats are absent.
(+) A cloudy white emulsion is formed if fats are present.

Question 9

What can fats/lipids be broken down into?

Answer 9

(3) Fatty acids and (1) Glycerol.

Question 10

What can proteins be broken down into?

Answer 10

Proteins -> Polypeptides -> Amino Acids

Question 11

What can glycogen be broken down into?

Answer 11

Glucose (omg what)