Answer: 1. - Fuels created from the remains of dead organisms.
2. - The number of organisms living in a particular area.
3. - Water falling from the atmosphere as a liquid or solid. (rain, snow, hail, or ice pellets)
4. - An organism that can make its own food.
5. - A close relationship between organisms of different species.
6. - Area of land that drains water to a common location.
