All MCQs

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.

Lymphocytes, especially B and T cells, are central to adaptive immunity. Defects can weaken antibody and cell-mediated responses.

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

Cutaneous respiration requires blood flow near the skin to carry absorbed oxygen to tissues and remove carbon dioxide.

After feeding, the digestive tract requires increased blood supply for absorption, transport, and metabolic processing of nutrients.

Activated B lymphocytes can differentiate into plasma cells that secrete antibodies specific to an antigen.

Hemolymph is a primary circulatory fluid in open systems. Vertebrate lymph is tissue fluid collected by lymphatic vessels and returned to blood.

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

Vasoconstriction reduces vessel diameter and increases resistance, often raising blood pressure if other factors remain similar.

Pulmonary circulation moves blood from the heart to the lungs and back. Systemic circulation moves blood between the heart and body tissues.