The words for the definitions are the following:
1. Scale used to describe how acidic or basic a solution is: pH scale
2. Affects the enzymes within living systems: Temperature, pH and concentration can affect enzymes.
3. Contamination of the environment beyond natural correction: Pollution.
4. An organism facing extinction through destruction of habitat: endangered species.
5. The ceasing of the existence of any particular species: extintion.
6. A pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of an ecosystem: biogeochemical cycle.
7. A process of land use change in which plants and animals which previously used the site are displaced or destroyed: habitat loss.
8. A theory of overall increase in world near-surface air and ocean temperatures: global warming.
9.The increase of temperature would cause significant changes in rainfall patterns, a rise in sea level and a wide range of impacts: climat change.