NEET Zoology - MCQ Practice Questions

Pepsin is a protease activated in the acidic stomach environment, cleaving peptide bonds in proteins to form polypeptides and oligopeptides.

Parkinson's disease results from loss of dopaminergic neurons in the substantia nigra, causing dopamine deficiency and characteristic motor symptoms.

Glucagon is secreted by alpha cells of pancreatic islets during fasting and increases blood glucose by promoting glycogenolysis and gluconeogenesis.

The glomerulus with Bowman's capsule forms the renal corpuscle, which is the site of ultrafiltration where small molecules are filtered from blood.

Myosin heads bind to specific sites on actin filaments, forming cross-bridges that enable muscle contraction through the sliding filament mechanism.

Deoxygenated blood returns to right atrium, passes to right ventricle, pumped to lungs, oxygenated blood returns to left atrium, then left ventricle, and exits via aorta.

The typical resting membrane potential is -70 mV, maintained by the Na+/K+ ATPase pump and selective membrane permeability.

Carbohydrate digestion begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase and brush border enzymes.

The lens adjusts its shape (accommodation) through ciliary muscle contraction to focus light precisely on the retina for clear vision.