Only 1 and 2 are correct. A major difference between active and passive immunity is that active immunity requires a. acquisition and activation of antibodies. They are contained only within the lymphatic vessels and nodes. They may mature in either bone marrow or the thymus gland. All cells differentiate only from pluripotent stem cells.
Many cells populate organs, such as the spleen or the tonsils, after maturity.
All cells are produced in bone marrow. Contractile vacuoles most likely would be found in protists a. in a marine environment. Most terrestrial animals dissipate excess heat by a. countercurrent exchange. I and IV 59. The advantage of excreting wastes as urea rather than ammonia is that 1. urea is less toxic than ammonia.