AIIMS2012ZoologyChemical Coordination and Integration
Assertion : Less iodine intake causes goitre. Reason : Less iodine in body decreases thyroxine secretion.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false
Correct answer
A. If both assertion and reason are true and reason is the correct explanation of assertion
Step-by-step solution
(a) : Simple goitre or endemic goitre is the enlargement of thyroid gland accompanied with cretinism or myxoedema. It occurs in case of hyposecretion of thyroxine. To compensate for lower secretion of thyroxine from cells, thyroid gland enlarges to accommodate more secretory cells. It is caused due to dietary deficiency of iodine. To form normal quantities of thyroxine about 1 mg / week of ingested iodine is required in the form of iodides.