Question

My question is related to transportation topic under chapter 1 life processes and the question is if human need blood for transportation of oxygen for oxidation in cells where do this blood comes from is it in fixed amount since birth or generated and if generated then how

Answer 1

Blood cells consists of red blood blood cell, white blood cell and platelets.
Blood cells do not originate in the bloodstream itself or in fixed amount from birth.Blood forms in specific blood-forming organs, mostly in the marrow of certain bones. In the human adult, the bone marrow produces all of the red blood cells, 60–70 percent of the white cells, and all of the platelets.
In our body, blood cell dies due to aging and generated by bone marrow, this cycle keep on going continuously.
The rate of blood cell formation varies depending on the individual, but a typical production might average 200,000,000,000 red cells per day, 10,000,000,000 white cells per day, and 400,000,000,000 platelets per day.