Define it:
(i) biodiversity (ii) ecosystem
Biodiversity - The variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered being important and desirable.
Ecosystem - An ecosystem is a community of living organisms with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are linked through nutrient cycles and energy flows.