_____ is the struggle among living things to survive

_____ happens when harmful things get into the air, land, and water.

To _____ means to use less of something.

To _____ means to turn old things into new things.

To _____ means to use something again.

A _____ happens when dry land becomes covered with water.

A _____ happens when there is no rain for a long period of time.

All the members of ONE kind of organism make up the _____.

All the populations together make up a _____.

An organism is ____ when there is little of its kind left.

_____ are the remains of things from long ago.

An organism is _____ when there is no more of its kind left.