All MCQs

Open circulation can be adequate for animals with lower metabolic demands. Many bivalves are less active and do not require high-pressure delivery systems.

Closed systems maintain blood within vessels, allowing higher pressure and more precise distribution to active tissues. This supports greater activity in many animals.

Hemocyanin is a copper-containing respiratory pigment found in many arthropods and molluscs. Oxygenated hemocyanin is often bluish.

Hemoglobin binds oxygen reversibly in red blood cells, allowing blood to carry far more oxygen than plasma alone.

Small or flat animals may exchange materials effectively by diffusion because cells are close to the external environment. Large animals require transport systems.

Large animals have cells far from the external environment. Circulatory systems transport gases, nutrients, wastes, hormones, and immune components efficiently.

Hemocytes in many invertebrates participate in phagocytosis, encapsulation, clotting, and antimicrobial defense within hemolymph.

Invertebrates generally lack vertebrate-style adaptive immunity but possess effective innate defenses, including barriers, phagocytic cells, antimicrobial peptides, and clotting-like responses.

T cells coordinate immune responses and can kill infected cells. They are central to cell-mediated adaptive immunity.

B cells can differentiate into plasma cells that secrete antibodies. Antibodies bind specific antigens and assist pathogen neutralization or removal.

Vaccines expose the immune system to antigens safely, leading to memory cells. Future exposure produces faster and stronger responses.

Innate immunity responds quickly to general patterns of infection or injury. It is less specific than adaptive immunity but essential for immediate defense.