Practice Pakistan questions with answers and explanations.
Choose an option to check your answer.
Lymphocytes, especially B and T cells, are central to adaptive immunity. Defects can weaken antibody and cell-mediated responses.
Choose an option to check your answer.
B cells can differentiate into plasma cells that secrete antibodies. Antibodies bind specific antigens and assist pathogen neutralization or removal.
Choose an option to check your answer.
Cutaneous respiration requires blood flow near the skin to carry absorbed oxygen to tissues and remove carbon dioxide.
Choose an option to check your answer.
After feeding, the digestive tract requires increased blood supply for absorption, transport, and metabolic processing of nutrients.
Choose an option to check your answer.
Activated B lymphocytes can differentiate into plasma cells that secrete antibodies specific to an antigen.
Choose an option to check your answer.
Hemolymph is a primary circulatory fluid in open systems. Vertebrate lymph is tissue fluid collected by lymphatic vessels and returned to blood.
Choose an option to check your answer.
T cells coordinate immune responses and can kill infected cells. They are central to cell-mediated adaptive immunity.
Choose an option to check your answer.
Vasoconstriction reduces vessel diameter and increases resistance, often raising blood pressure if other factors remain similar.
Choose an option to check your answer.
Pulmonary circulation moves blood from the heart to the lungs and back. Systemic circulation moves blood between the heart and body tissues.
Choose an option to check your answer.
Cytotoxic T cells recognize infected cells and kill them, limiting viral replication. This is a key cell-mediated immune response.
Choose an option to check your answer.
Invertebrates generally lack vertebrate-style adaptive immunity but possess effective innate defenses, including barriers, phagocytic cells, antimicrobial peptides, and clotting-like responses.
Choose an option to check your answer.
Exercise increases tissue oxygen and nutrient demand. Higher heart rate and cardiac output increase delivery and waste removal.
