In multi-celullar organisms , the cell cycle produces groups of cells that perform the same function. These groups of cells form what it is called a tissue. A tissue is made up of cells that all are specialised to perform the same function. A bunch of tissues form an organ. Organs are more complex in structure and functions.
lots of different organs together form an organ system.
A food chain can usually sustain no more than six energy transfers before all the energy is used up. And so less energy is transferred at each level of the food chain so the biomass gets smaller.