Science MCQs

During exhalation, the rib muscles relax and the diaphragm relaxes (curves upward), reducing chest volume.

Breathing is the physical process of inhaling/exhaling. Respiration is the chemical process of releasing energy from glucose.

Yeast undergoes alcoholic fermentation, producing ethanol and carbon dioxide in the absence of oxygen.

Arteries carry blood under high pressure from the heart, so they have thick, muscular walls.

The superior and inferior vena cava are large veins that return deoxygenated blood to the right atrium.

Valves in veins ensure that blood flows only toward the heart and does not flow backward.

White blood cells (WBCs) help fight infections and are a key part of the immune system.

Serum is plasma without fibrinogen (clotting proteins).

A heart attack occurs when a coronary artery is blocked, cutting off blood supply to part of the heart muscle.

Weight loss, regular exercise, and a healthy diet can help prevent hypertension.