NEET Zoology - MCQ Practice Questions

Dystrophin is a structural protein that stabilizes muscle cell membranes; its absence causes Duchenne muscular dystrophy with progressive muscle weakness.

The hypothalamus acts as the body's thermostat, detecting temperature changes and triggering responses (sweating, vasoconstriction) through negative feedback mechanisms.

Exercise triggers increased respiratory and heart rates, enhancing oxygen delivery to muscles through elevated blood flow and ventilation.

PTH is secreted by parathyroid glands in response to hypocalcemia, increases calcium reabsorption in kidneys, and promotes calcium mobilization from bones.

The symptoms (polydipsia, polyuria, fatigue) along with elevated blood glucose and reduced insulin indicate Type 1 diabetes mellitus, where autoimmune destruction of pancreatic beta cells occurs, reducing insulin production.

The counter-current multiplier system in the loop of Henle (particularly the thick ascending limb) creates an osmotic gradient that enables water reabsorption in the collecting duct, essential for urine concentration.