What can be learned by studying fossils (think in terms of ecology, what role does the environment play in the evolution of species)?

By studying fossils one can understand how long life has existed on earth.

The relation between the different types of plants and animals. How are they ancestrally related to each other.

Environment plays a huge role in preserving the fossils which can be used to know the information about the plants and animals.

It can also be used to know the environment which was found at that time. It can easily tell about the past time, the environment and everything about the past time.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.