Question

Due to decreased light penetration, which area of rivers and streams will have less diversity of plant life? a. the source b. the mouth c. the middle portion d. none of the above

Answer 1

The middle portion, because that is supposedly where all the vegetation is, like trees etc. So they would provide shade and absorb photons of light before much of it can penetrate through to the river bed.

Obviously that is assuming the question is referring to river bed plants