It's just necessary
because
There are several enzymes that are necessary for the metabolism of living organisms. Some of them include bile, pancreatic fluid and carbohydrates.
Carbon is necessary for all living things.
I am not sure that sodium carbonate is necessary for human beings.
no
respiration
Plants are living things. All living things need water.
having a brain
There are millions of family members living. =If you mean of a particular family it is necessary to give a name.
It is not absolutely necessary, but it will make life a lot easier if you can speak the language of the country you are living in.
It is to ensure that their own kind will continue to exist.