Question 1

The thyroid hormones (T₃ and T₄) require the element ______ for their synthesis:

Accepted Answer

Iodine. Iodine is essential for thyroxine (T₄) and triiodothyronine (T₃) synthesis.

Question 2

Enlargement of the thyroid gland due to dietary iodine deficiency is called:

Accepted Answer

Goitre. Iodine deficiency → low thyroxine → thyroid enlarges (simple goitre).

Question 3

Hyposecretion of thyroid hormones during pregnancy/childhood can cause ______ in the newborn:

Accepted Answer

Cretinism (stunted growth, mental retardation). Congenital hypothyroidism causes cretinism — stunted growth, low IQ, deaf-mutism.

Question 4

The parathyroid hormone (PTH) raises blood calcium levels; it is therefore called a ______ hormone:

Accepted Answer

Hypercalcemic. PTH is hypercalcemic — it increases blood Ca²⁺ by acting on bone, kidney and gut (opposed by calcitonin).

Question 5

Calcitonin (from the thyroid) and parathormone (from parathyroids) act antagonistically to regulate:

Accepted Answer

Blood calcium levels. Calcitonin lowers and PTH raises blood Ca²⁺ — together they maintain calcium homeostasis.

Question 6

Thyroxine is also a major regulator of the ______ and influences ______:

Accepted Answer

Basal metabolic rate (BMR); growth, RBC formation and tissue development. Thyroxine controls BMR and supports normal growth, erythropoiesis, and metabolism of carbohydrates, fats and proteins.

Question 7

The thyroid gland consists of two lobes on either side of the trachea, connected by a connective-tissue bridge called the:

Accepted Answer

Isthmus. The two thyroid lobes are joined across the trachea by a thin flap of connective tissue called the isthmus.

Question 8

Which thyroid hormone lowers blood calcium levels by acting on bone and kidney?

Accepted Answer

Calcitonin (thyrocalcitonin). Calcitonin, secreted by the thyroid, is a hypocalcemic hormone; it lowers blood Ca2+ by inhibiting bone resorption and promoting calcium loss in urine.

Question 9

Thyroid hormones raise the basal metabolic rate. Their over-secretion (hyperthyroidism) would therefore be expected to cause:

Accepted Answer

Weight loss with an elevated basal metabolic rate. Excess thyroid hormone increases the basal metabolic rate, accelerating catabolism and typically causing weight loss despite normal or increased appetite.

Question 10

The number of parathyroid glands normally embedded on the back of the thyroid in humans is:

Accepted Answer

Four (two pairs). Humans typically have four parathyroid glands — two pairs — located on the posterior surface of the thyroid lobes.

Question 11

Parathyroid hormone raises blood calcium. Which set of actions correctly describes how it does so?

Accepted Answer

Stimulates bone resorption, increases renal Ca2+ reabsorption, and promotes intestinal Ca2+ absorption (via vitamin D). PTH is hypercalcemic: it mobilises Ca2+ from bone (osteoclast stimulation), enhances renal reabsorption of Ca2+, and promotes intestinal absorption of calcium via activation of vitamin D.

Question 12

Assertion (A): A diet chronically deficient in iodine can lead to goitre. Reason (R): Without iodine the thyroid cannot make adequate T3/T4, and reduced feedback drives excess TSH that enlarges the gland. Choose the correct option.

Accepted Answer

Both A and R are true and R is the correct explanation of A. Iodine deficiency lowers T3/T4 output; the reduced negative feedback raises TSH, which hypertrophies the thyroid, producing simple (endemic) goitre — so R correctly explains A.

Question 13

Calcitonin and parathormone regulate calcium homeostasis antagonistically. Which statement about this pair is correct?

Accepted Answer

Calcitonin lowers blood Ca2+ (hypocalcemic) while PTH raises it (hypercalcemic). Calcitonin (thyroid) is hypocalcemic and PTH (parathyroid) is hypercalcemic; together they act antagonistically to keep blood calcium within narrow limits.

Question 14

Which of the following statements about thyroid dysfunction and its effects is INCORRECT?

Accepted Answer

Hypothyroidism in an adult woman never affects the menstrual cycle. Thyroid hormones affect the menstrual cycle, so hypothyroidism in women can cause menstrual irregularities — that statement is false. Cretinism, water-electrolyte balance and growth effects are all correct.

Question 15

A child shows stunted growth, intellectual disability, low body temperature and retained (deaf-mute) features. This clinical picture, arising from thyroid hormone deficiency in early life, is called:

Accepted Answer

Cretinism. Congenital or early hypothyroidism produces cretinism — stunted growth, mental retardation, low body temperature and often deaf-mutism. Myxoedema is adult-onset hypothyroidism.

Question 16

The exophthalmic goitre marked by protruding eyeballs, raised metabolic rate and thyroid enlargement due to over-secretion of thyroid hormones is known as:

Accepted Answer

Grave's disease. Grave's disease is a hyperthyroid condition featuring exophthalmos (bulging eyes), goitre and an elevated metabolic rate, in contrast to the hypothyroid conditions cretinism and myxoedema.

Question 17

Deficiency of iodine in the diet results in:

Accepted Answer

Hypothyroidism. Iodine deficiency impairs thyroxine synthesis, producing hypothyroidism (goitre).

Question 18

Thyrocalcitonin (TCT) is a:

Accepted Answer

Protein (peptide) hormone. Thyrocalcitonin is a peptide/protein hormone secreted by the thyroid.

Question 19

In adult women, hypothyroidism may cause:

Accepted Answer

Irregular menstrual cycle. Hypothyroidism in adult women can disturb the menstrual cycle, making it irregular.

Question 20

Which of the following disorders is a form of hyperthyroidism?

Accepted Answer

Exophthalmic goitre. Exophthalmic goitre (Grave's disease) is a form of hyperthyroidism, whereas myxoedema and cretinism are hypothyroid conditions.

Thyroid & Parathyroid — NEET Biology MCQs with Solutions

Questions with solutions