Which is an electromagnetic wave? a. a vibrating guitar string
b. a flag waving in the wind
c. the waves that heat a cup of water in a microwave oven
d. the changes in the air that result from blowing a horn

Ricardo notices that when he plays soccer in the rain, his ball does not seem to go as far after a kick. what is the best scientific question that ricardo could ask about this observation? is soccer better played in the rain or sun? how does rain affect the distance a soccer ball can travel? how does rain affect the speed of a soccer ball? is soccer affected by the rain?

In a cladogram' when does a group of organisms branch off

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important