Compare and contrast each pair of related terms. substance and mixture

A substance can be defined as a matter that has the same composition and properties while a mixture can be defined as  a combination of two or more substance where each substance present in a mixture retain their properties.
Also, a substance contains only one compound while a mixture is a combination of one or two compounds. 

to make it brief.

Nature really doesn't really care what happens to you after you reproduce. That is the meaning of life pretty much.

That being said-
Asexual reproduction is awesome because one cell can separate many times over a short period of time. 

Although sexual reproduction takes longer, it allows the offspring to have a more diverse set of genes than it's parents do. This can make an immunity to a disease stronger.
 
That is where asexual reproduction fails. If one disease can kill a cell that uses asexual reproduction, it can kill all its offspring because they all have the same dna.