It was observed that the tadpoles are not growing into adult frogs in a village pond. A scientist who was asked to find the reason for this concluded that the pond water did not contain sufficient amount of a mineral P which could make a hormone Q. The hormone Q can causes a phenomenon R in tadpoles so that they become adult frogs.
(a) What are (i) P (ii) Q, and (ii) R?
(b) name one human disease which can also be caused due to the deficiency of P in the food and water.
(a) (i) iodine (ii) Thyroxine (ii) Metamorphosis
(b) Iodine is needed continuously by thyroid gland to make thyroxine hormone. If people do not have enough iodine in their die, they will get goiter disease caused by lack of thyroxine. So, people are advised to use iodized salt in cooking food.