The average adult heart pumps about 84./mls of blood at 72 beats per minute. suppose you need to calculate how long it would take the average heart to circulate 3500.ml of blood.

Taking in account that an adult heart pumps 84 ml each beat and 72 beats per minute that means 84*72=6048 ml/min, then to pump 3500 ml needs less than a minute, so then 3500 * 60 / 6048 = 34.72 seconds. Solution: Heart needs 34.72 seconds to pump 3500 ml, or 41.67 beats

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.