Food

Question 1

The need for food

Answer 1

Nutrition is the way in which an organism obtains and uses its food
Nutrients are used for the following reasons:
1. as a source of energy
2. to make chemicals needed fro metabolic reactions
3. for growth and repair

Question 2

Chemical elements of food

Answer 2

1. Carbon (C)
2. Hydrogen (H)
3. Oxygen (O)
4. Nitrogen (N)
5. Phosphorus (P)
6. Sulphur (S)

Question 3

5 elements present in dissolved salts:

Answer 3

1. Sodium (Na)
2. Magnesium (Mg)
3. Chlorine (Cl)
4. Potassium (K)
5. Calcium (Ca)

Question 4

3 trace elements:

Answer 4

1. Iron (Fe)
2. Copper (Cu)
3. Zinc (Zn)

Question 5

Bio-molecular Structures

Answer 5

These are combinations of elements in different ratios.

Question 6

4 types of biomolecules:

Answer 6

1. Carbohydrates
2. Lipids (fats, oils)
3. Proteins
4. Vitamins

Question 7

Carbohydrates are made of…

Answer 7

Carbon, Hydrogen and Oxygen.

Question 8

Carbohydrate ratio:

Answer 8

Cₓ(H₂O)ᵧ where x and y are equal. e.g. the
formula for Glucose is
C₆H₁₂O₆

Question 9

Monosaccharides

Answer 9

(made of single units) e.g. Glucose

Question 10

Disaccharides

Answer 10

(made of two monosaccharides joined together) e.g. Sucrose

made of glucose and fructose units

Question 11

Polysaccharides

Answer 11

(contain many monosaccharides linked together) e.g.
1. Starch – made of glucose units (plants store glucose in this form)
2. Cellulose – made of glucose units that are heavily cross-linked
(humans cannot digest it but use it as fibre to stimulate peristalsis)
3. Glycogen – made of glucose units (humans store glucose in this form
in the Liver).

Question 12

Lipids are made of…

Answer 12

Carbon,
Hydrogen and Oxygen.

Unlike carbohydrates they have no
simple ratio (they can be recognised
from a formula, however, as they
have very little oxygen compared to
the amounts of carbon and hydrogen)

Question 13

Trigliceride structure

Answer 13

Small lipids made of a glycerol

molecule linked to three fatty acid molecules.

Question 14

Phospholipids

Answer 14

fats with a phosphate instead of one of the fatty acid molecules.

Question 15

Proteins are made of…

Answer 15

Carbon, Hydrogen, Oxygen and Nitrogen.

- They sometimes contain small amounts of Sulphur

Question 16

Proteins are composed of…

Answer 16

Amino acids

• 20 types of amino acid.
• arranged into long chains.
• the bond between amino acids is called a peptide bond.

Question 17

Fibrous proteins

Answer 17

show little or no folding. e.g. keratin in hair and nails

Question 18

Globular proteins

Answer 18

show lots of folding. They form rounded shapes e.g. enzymes

Question 19

Water-soluble Vitamins

Answer 19

• e.g. Vitamin C
• Sources include citrus fruits
• lack of vitamin C results in Scurvy

Question 20

Fat-soluble Vitamins

Answer 20

• e.g., Vitamin D
• Sources include Liver, fish oils
• Lack of Vitamin D results in Rickets

Question 21

Anabolic Reactions

Answer 21

These reactions convert smaller molecules into larger ones.
e.g. Photosynthesis
6CO₂ + 6H₂O + Light 
→ 
C₆H₁₂ O₆ + 6O₂

Question 22

Catabolic Reactions

Answer 22

These reactions break down complex molecules into simpler ones
e.g. Respiration
C₆H₁₂ O₆ + 6O₂ 
 →
6CO₂ + 6H₂O + energy