No. In other living organisms as well
It helps transports oxygen through-out the body.
its inside our body
1) Frog's red blood cells contain a nucleus that carries all the genetic information needed to make new cells by replication. Human red blood cells contain no nuclei because they reproduce...
Yes there are some differences, see the related link below.
Because it is the part of the RBC that carries oxygen. It's not needed in WBCs