Question

Natural rubber comprises of all transpolyisoprene units

Answer 1

Natural rubber is actually consist of polymers of the isoprene (polyisoprene).and chemically it is consist of  resins , balata as well as the  gutta purcha .
In the form of polyisoprene there are four isomers present .
These four are
1)  trans 1-4 polymer 
2) cis 1-4 polymer 
3)1,2 polymer and 4) 3,4 polymer

Of these first two are really important and most abundant.
Trans-1,4 polyisoprene are present mostly in balata as well as the ghutta parcha and being the crystalline it makes them  toughness as well as the hardness  and makes leathery material