NEET Biology Chemical Coordination and Integration MCQs Set 04

Answer: (c) Thyrocalcitonin

Explanation:
1. Thyrocalcitonin (calcitonin) lowers blood calcium by inhibiting bone resorption.
2. PTH raises calcium.

Teacher's Note:
1. TCT and PTH are antagonists.
2. TCT comes from thyroid parafollicular cells.

Answer: (b) Vitamin D

Explanation:
1. Vitamin D deficiency reduces calcium absorption and causes rickets or osteomalacia, deforming bones.
2. PTH deficiency affects blood calcium rather than bone shape.

Teacher's Note:
1. Rickets: children.
2. Osteomalacia: adults.

Answer: (b) Addison's disease

Explanation:
1. Hyposecretion of adrenal cortex hormones causes Addison's disease.
2. Features: low blood pressure, weakness and skin pigmentation.

Teacher's Note:
1. Cortisol and aldosterone deficiency.
2. Hypersecretion gives Cushing's syndrome.

Answer: (a) Increased blood sodium levels

Explanation:
1. Zona glomerulosa secretes aldosterone, which increases sodium reabsorption.
2. A tumour therefore raises blood sodium.

Teacher's Note:
1. Aldosterone: Na+ retention, K+ loss.
2. Also raises blood pressure.

Answer: (c) Catecholamine

Explanation:
1. Epinephrine and norepinephrine are catecholamines made from tyrosine.
2. They are neither steroids nor proteins.

Teacher's Note:
1. Catecholamines come from adrenal medulla.
2. They are fight or flight hormones.

Answer: (a) Adrenal cortex

Explanation:
1. Aldosterone from the adrenal cortex retains sodium in the body.
2. Medulla secretes adrenaline.

Teacher's Note:
1. Mineralocorticoid action.
2. Works on distal tubule.

Answer: (d) Ecto - mesodermal in origin

Explanation:
1. The adrenal cortex is mesodermal and the medulla is ectodermal in origin.
2. Therefore the gland has a combined ecto-mesodermal origin.

Teacher's Note:
1. Cortex: mesoderm.
2. Medulla: neural crest.

Answer: (a) Renin

Explanation:
1. Renin from the kidney forms angiotensin II, which stimulates zona glomerulosa to release aldosterone.
2. Thyroxine, ADH and FSH do not control it.

Teacher's Note:
1. Renin-angiotensin-aldosterone system.
2. It acts when blood pressure falls.

Answer: (d) All of the above

Explanation:
1. Vitamin D increases calcium absorption from the gut.
2. Its deficiency in children produces rickets, and it promotes bone formation (osteoblastic activity).

Teacher's Note:
1. All statements are correct.
2. Vitamin D acts like a hormone.

Answer: (c) Thyroid

Explanation:
1. The thyroid gland takes up and holds the largest amount of iodine in the body.
2. It needs iodine to make thyroxine.

Teacher's Note:
1. Iodine is needed for T3 and T4.
2. Deficiency causes goitre.

Answer: (d) Cushing's syndrome

Explanation:
1. Cushing's syndrome is due to excess cortisol and shows moon face, hyperglycaemia and virilism.
2. Addison's is hypo and Grave's relates to the thyroid.

Teacher's Note:
1. Excess glucocorticoid.
2. Often with high blood pressure.

Answer: (d) Parathyroid hormone

Explanation:
1. Parathormone deficiency lowers blood calcium, which causes tetany (muscle spasms).
2. Other hormones do not control blood calcium directly.

Teacher's Note:
1. Low calcium raises nerve excitability.
2. PTH deficit gives tetany.

Answer: (b) Thyroid gland is destroyed by autoimmunity

Explanation:
1. Hashimoto's disease is an autoimmune destruction of the thyroid gland.
2. It causes hypothyroidism.

Teacher's Note:
1. Autoimmune hypothyroidism.
2. Grave's disease is autoimmune hyperthyroidism.

Answer: (b) Endoderm

Explanation:
1. The thymus develops from endoderm of the third pharyngeal pouch.
2. It lies in the upper chest in front of the heart.

Teacher's Note:
1. Thymus: endodermal.
2. Parathyroid III and IV pouches.

Answer: (b) Thymus gland

Explanation:
1. Hassall's corpuscles are concentric structures of epithelial cells found in the thymus medulla.
2. They are absent from the other glands listed.

Teacher's Note:
1. Hassall's corpuscles: thymus.
2. Thymus matures T cells.

Answer: (c) No adverse reaction

Explanation:
1. In an adult most T cells are already formed and distributed in lymphoid organs.
2. So removal of the thymus in adulthood has little adverse effect.

Teacher's Note:
1. Thymus is large in the young.
2. It shrinks with age.

Answer: (d) Pancreas

Explanation:
1. Insulin from the pancreas converts glucose into glycogen in the liver (glycogenesis).
2. It lowers blood glucose.

Teacher's Note:
1. Insulin is the hypoglycaemic hormone.
2. Glucagon acts in reverse.

Answer: (d) Pancreas

Explanation:
1. The pancreas has exocrine acini (digestive enzymes) and endocrine islets (insulin, glucagon).
2. So it is both exocrine and endocrine.

Teacher's Note:
1. Pancreas is heterocrine.
2. Gonads are also heterocrine.

Answer: (b) a (alphs) cells of islets of langerhans

Explanation:
1. Glucagon is secreted by alpha cells of the islets of Langerhans.
2. Beta cells secrete insulin.

Teacher's Note:
1. Alpha: glucagon.
2. Beta: insulin; delta: somatostatin.

Answer: (b) Increase glycogenolysis

Explanation:
1. Insulin increases glycogenesis, amino acid uptake and glucose oxidation.
2. Glycogenolysis is promoted by glucagon, not insulin.

Teacher's Note:
1. Insulin promotes storage.
2. Glucagon promotes release.

Answer: (d) Glucagon

Explanation:
1. Glucagon opposes insulin and raises blood glucose, so it has an anti-insulin effect.
2. Cortisol also raises glucose but glucagon is the direct antagonist.

Teacher's Note:
1. Insulin and glucagon are antagonists.
2. They maintain glucose homeostasis.

Answer: (d) All the above

Explanation:
1. Insulin deficiency leaves blood glucose high.
2. Fat breakdown produces ketone bodies causing ketoacidosis, and glucose loss causes dehydration.

Teacher's Note:
1. Diabetic coma is life threatening.
2. All three changes occur.