1. There was major period of angiosperm diversification andradiation between 110 and 90
million years ago. For many years the dominant view was that thisreflected coevolution
with insects, which were also thought to have diversified duringthis period. This view is
now thought to be overly simplistic. Briefly outline evidence forand against this view,
and give an account of the various other processes that may havebeen involved.
2. \"Water in the xylem is under negative pressure, or tension\".Explain what this
statement means, how this physical situation comes about, what therisks are for plants
because of it, and describe some adaptations that help minimizethese risks or cope with
the consequences.
