Because the soil didn't have the same nutrients it has now due to lack of decomposition of other plants and animals.
All living cells arise from pre existing cells.
C. Mutuality Relationship.
They have a mutual relationship by which both benefit.
When the hummingbird takes a sip off the daffodil, they are not sucking their strength out, they are simply sucking out pollen, which they then transfer to other flowers.
This process benefits both the plant and the bird.
Animal cells do not have cell walls because they do not need them. Cell walls, which are found in plant cells, maintain cell shape, almost as if each cell has its own exoskeleton.
