2018 WAEC Biology Theory Diagrams A, B and C are illustrations of different types of teeth in humans. Diagram...

WAEC 2018

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 jaw of a human.

Study them and answer questions (a) to (f).
(a) (i) Name the type of teeth in diagrams A, B, and C.

(ii) Which of the teeth would be found in positions I, II and IV?

(iii)State one function each of the teeth illustrated in diagrams A, B and C.

(iv) State one reason each for the answers in (a) (iii).

(b)If the tooth labeled B is decayed, list two factors that may be responsible.
(c)What is the total number of each of the teeth labeled A, B and C in the dentition of an adult human?
(d)Which of the teeth would be absent in a rabbit?
(e)(i)  Name the tooth that would be found in position III of diagram D.
(ii) In which of the parts labeled I, II, III and IV would a tooth not be found in an infant?
(f)  State five ways of caring for the teeth in humans.

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Explanation

(a) (i) Name of teeth

A: Canine
B: Molar
C: Incisor

(ii) Teeth found in position I, II and IV
I – Incisor
II – Canine
IV – Molar

(iii) Functions of each of the teeth
A - Canine: For tearing flesh/ piercing.
B - Molar: For breaking/ crushing/ chewing/ grinding.
C - Incisor: For cutting/biting

(iv) Reason for the answer
A - Canine: It is conical/ sharp / pointed.
B - Molar: It is broad with ridges/ cusps on surface.
C - Incisor: It has (flat) sharp/ chisel-shaped edge.

(b) Factors responsible for tooth decay

Acid accumulation.
Bacterial/microbial/fungal activity.
Food remnants/sweet/sugary/sticky foods.
Improper use of teeth can lead to cracks e.g. cracking hard bones with teeth, opening bottle tops with teeth.
Lack of proper care of teeth/ unhygienic dental practices.
Lack of fluoride/ vitamins/ minerals (in food).

            (d) The tooth that is absent in a rabbit
A/Canine
(e) (i) Name of tooth in III of diagram D
Premolar

(ii) Teeth absent in an infant
Molar/IV
(f) Care of the teeth in humans

Brushing the teeth regularly/after meals/before going to bed;
Avoiding smoking and excessive alcohol;
Eating vitamins and mineral-rich foods regularly (fruits);
Reducing the intake of sweet/sticky/sugary foods (that may allow bacterial growth);
Visiting the dentist at least twice a year/every six months;
Removing food particles from teeth using tooth pick;
Washing/ flossing teeth with germicide solution e.g. hydrogen peroxide;
Avoiding hard objects that may break the teeth, /e.g., removal of cork/bottle tops/cracking large bones.

Scraping the plaque on teeth with appropriate material/ tool/ scrapper.

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