Biology assistance needed ASAP

Please answer the questions below and be sure to cite the source.

1. How are keystone species linked to species richness?   Provide an example of a keystone species.

2. Provide a specific example of how a trophic level in a food chain might occasionally interact with another food chain and in doing so, become part of a larger food web.  You may make up an example if you wish.

3. Some countries are becoming more affluent:   China and India, for example.   Describe two ways in which greater, more widespread affluence is likely to affect the global ecosystem.