Thyroid Gland Structure and Iodine — NEET Biology
📚 Practice ConceptThe thyroid gland is composed of two lobes which are located on either side of the trachea. Both the lobes are interconnected with a thin flap of connective tissue called isthmus. The thyroid gland is composed of follicles and stromal tissues. Each thyroid follicle is composed of follicular cells, enclosing a cavity. These follicular cells synthesise two hormones, tetraiodothyronine or thyroxine (T₄) and triiodothyronine (T₃). Iodine is essential for the normal rate of hormone synthesis in the thyroid. Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre. Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental
Which of the following statements regarding thyroid gland and its disorders are NOT correct? S1: Goitre is an enlargement of the thyroid gland primarily caused by insufficient intake of iodine in the diet. S2: Cretinism, characterized by mental retardation and stunted growth, is a condition arising from hyperthyroidism in adults. S3: Exophthalmic goitre, or Graves' disease, is a form of hyperthyroidism marked by decreased basal metabolic rate and weight gain. S4: Thyroid hormones play a crucial role in regulating basal metabolic rate, metabolism of carbohydrates, proteins, and fats. S5: Thyrocalcitonin (TCT) is a protein hormone that functions to raise blood calcium levels in coordination with PTH.
View solution & NCERT explanation
Correct answer: D — S2, S3 and S5 only
S1 is correct. "Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre." S2 is incorrect. Cretinism results from hypothyroidism during pregnancy or infancy, not hyperthyroidism in adults. S3 is incorrect. Exophthalmic goitre (hyperthyroidism) is characterized by increased basal metabolic rate and weight loss, not decreased BMR and weight gain. S4 is correct. "Thyroid hormones play an important role in the regulation of the basal metabolic rate. These hormones control the metabolism of carbohydrates, proteins and fats." S5 is incorrect. TCT is a protein hormone that functions to decrease blood calcium levels. Therefore, S2, S3, and S5 are NOT correct. This question assesses knowledge of thyroid disorders, their causes, symptoms, and the specific functions of thyroid hormones.
What does NCERT say about thyroid gland composed two?
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
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