(A) (a) Analyse the given situations and interpret the possible reason for each : (i) Iodine deficiency in…
(A) (a) Analyse the given situations and interpret the possible reason for each :
(i) Iodine deficiency in diet increases the possibility of a disease of swollen neck in a person.
(ii) Some people in population may have very short heights (dwarfs).
(iii) Thick facial hairs develop in boys at the age of 10-12 years.
(b) Explain two reasons which necessitate the need of chemical communication in multicellular organisms.
Solution
(A)(a)(i) Iodine is necessary for the thyroid gland to make thyroxin hormone, its deficiency causes goitre.
(ii)Deficiency of growth hormone in childhood causes dwarfism.
(iii)Secretion of testosterone during puberty in males.
(b) Hormones or chemical compounds can potentially reach all cells of body steadily and persistently.
Hormones help to coordinate growth, development and responses to environment.