ATP is adenosine triphosphate, it is like a fully charged battery in a cell, ADP is basically ATP that has been drained of its energy from a chemical reaction. It is like a dead battery that can be recharged later ;)
By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other. Often we can work out how and where they lived, and use this information to find out about ancient environments.
This is your own opinion. Write about what you would do as a forensic scientist and the good things about that job and vise versa for the least favorite.