Why do wind-pollinated plants need to produce a large amount of pollen? ?

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

Sediment layers stop lateral spreading when: they encounter a barrier they encounter an opposing current they run out of additional sedimentary material

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the