Question

why do organisms need to take in food

Answer 1

to get energy for metabolic activities to take place

Answer 2

As we know the body of all the living organisms present on the surface of earth are made up of cells. As long as the cells continue to function properly the body functions properly and the organism survives. When the cells do not function properly the body do not function properly and the organism dies. That means to suvive the cells of living organisms function properly.Now the cells require 2 things for function properly--

1)Raw materials to make its own molecules
2)Energy for carrying out metabolic reactions.

So the living organisms should provide its body the molecules that provide raw materials and energy to the cells. These materials are called as nutrients. The organism get these nutrients by food/diet. So we can say food provides raw materials and energy to the body. So food is the basic requirement of all living organisms.It mainly contains carbohydrates proteins and fats. Vitamins and minerals are present in also small amoynt.