Pakistan MCQs

Veins have thin walls and large lumens, allowing them to store much of the blood volume. They operate at low pressure.

In mammals, the right heart pumps deoxygenated blood to the lungs through pulmonary circulation. The left heart pumps oxygenated blood to the body.

Allergy results from inappropriate or exaggerated immune responses to harmless substances such as pollen, foods, or dust.

Inflammation recruits defenses and supports repair, but excessive or chronic inflammation can injure tissues and disturb normal function.

Active muscles need more oxygen and produce more carbon dioxide. Respiratory and circulatory systems work together to match gas exchange with demand.

The left ventricle generates high pressure for systemic circulation. Its thicker muscular wall matches the greater workload.

Vaccination initiates adaptive immune responses. Lymphocyte activation, antibody production, and memory formation take time.

Innate immune cells detect broad pathogen-associated patterns using pattern-recognition mechanisms. This differs from highly specific adaptive antigen receptors.

Immune defense involves detecting danger, signaling between cells, recruiting responses, eliminating threats, repairing tissues, and sometimes forming memory.

Fish gills are respiratory exchange organs. Blood picks up oxygen from water and releases carbon dioxide before flowing to the body.

Blood distribution changes with activity, digestion, temperature, and stress. Regulation ensures active tissues receive enough oxygen and nutrients.

Memory B and T cells persist after first exposure. On re-exposure, they mount faster and stronger responses.