Refer to the given dichotomous key and select the correct option.
I. (A) It is categorised as energy giving food. – Go to II
(B) It is categorised as protective food. – Go to III
II. (A) It is soluble in water. – 
(B) It is insoluble in water. – 
III. (A) It is needed for clotting of blood. – 
(B) It helps in formation of haemoglobin. – 
A Q could be glucose which is instant source of energy.
B Deficiency of S causes anaemia characterised by pale body colour, body fatigue etc.
C R causes osteoporosis in adults while S causes goitre in adults.
D P occurs in the cell wall of plant cells and in fibres.
Ans 6:
Class : Class 6
According to the dichotomous key P, Q, R and S could be glucose, cellulose, calcium and iron respectively. Goitre is caused by deficiency of iron. Cellulose is a complex carbohydrate occurs in the cell wall of plant cells and plant fibres.