Why is river water less clear at the mouth than at the source? a)because the source is warmer
b) because the mouth is warmer
c) because the mouth has debris
d) because the source is colder

Which flexible structure that supports the nerve cord and led to the backbone

List the advantages and disadavantages of the switch from persistent chlorinated hydrocarbon pesticides (such as ddt) to nonpersistent organophosphate pesicides. have the benefits of the switch outweighed the disadvantages? explain.

Modern whales developed their traits through natural selection what occurs during the process of natural selection