%IMG% Diagrams A, B and C are illustrations of different types of teeth in humans. Diagram D is a representation of the arrangement of teeth in the lower ja...

(a)(i) Type of teeth

• A: Canine.
• B: Molar.
• C: Incisor.

(a)(ii) Teeth found in positions I, II and IV

• I: Incisor.
• II: Canine.
• IV: Molar.

(a)(iii) One function of each

• A (canine): for tearing flesh and piercing food.
• B (molar): for breaking, crushing, chewing and grinding food.
• C (incisor): for cutting and biting food.

(a)(iv) One reason for each answer

• A (canine): it is conical, sharp and pointed.
• B (molar): it is broad with ridges (cusps) on its surface.
• C (incisor): it has a flat, sharp, chisel-shaped edge.

(b) Two factors that may cause decay of tooth B

• Accumulation of acid produced by bacteria acting on food remnants.
• Frequent eating of sweet, sugary or sticky foods with poor cleaning of the teeth.

(c) Total number in the dentition of an adult human

• A (canines): 4.
• B (molars): 12.
• C (incisors): 8.

(d) Tooth absent in a rabbit: the canine (A). A rabbit has a gap (diastema) in place of the canines.

(e)(i) Tooth in position III of diagram D: premolar.

(e)(ii) Part where a tooth is not found in an infant: position IV (the molar).

(f) Five ways of caring for the teeth

1. Brush the teeth regularly, after meals and before going to bed.
2. Reduce the intake of sweet, sticky and sugary foods.
3. Eat foods rich in vitamins and minerals, such as fruits, for strong teeth.
4. Visit the dentist at least twice a year (every six months) for check-ups.
5. Avoid using the teeth on hard objects (such as cracking bones or opening bottle tops) and avoid smoking and excessive alcohol.