All MCQs

Macrophages are phagocytes of innate immunity, but antigen presentation can help activate adaptive immune responses such as T cells.

Inflammation increases local blood flow and vascular permeability, bringing immune cells and defensive proteins to injury or infection sites.

Fever is a systemic innate response that can slow pathogen growth and enhance immune activity. It is not antigen-specific.

Physical and chemical barriers are innate defenses. They act broadly and immediately against many pathogens before specific immune responses develop.

Blocked lymph drainage prevents interstitial fluid from returning to blood, causing edema or swelling in tissues.

The lymphatic system returns excess tissue fluid to the bloodstream and also participates in immune defense through lymph nodes and lymphocytes.

Capillaries have very thin walls that permit diffusion and exchange between blood and tissues. Their structure fits exchange function.

Venous pressure is relatively low, especially in limbs. Valves help maintain one-way flow back to the heart.

Arteries receive blood directly from heart contractions and have elastic muscular walls that withstand high pressure.

Most reptiles have two atria and a partially divided ventricle. Crocodilians are exceptions with four-chambered hearts.

Four-chambered hearts fully separate oxygenated and deoxygenated blood. This supports efficient oxygen delivery and high metabolism.

Amphibians have two atria and one ventricle, allowing partial separation of blood streams. It is an intermediate condition between fish and birds/mammals.