Here are the corrections for the sentences:

11. If **there** too much pollution, it will affect the wildlife.
**Correction:** If **there is** too much pollution, it will affect the wildlife.

12. There will be fewer fish in the sea if we **keeps** polluting it.
**Correction:** There will be fewer fish in the sea if we **keep** polluting it.

13. We **don't** stop air pollution if we keep using cars and motorbikes.
**Correction:** We **won't** stop air pollution if we keep using cars and motorbikes.

14. **Will** we don't take care of our beaches, it will affect tourism.
**Correction:** **If** we don't take care of our beaches, it will affect tourism.

15. Who **will** happen if we keep polluting the land?
**Correction:** What **will** happen if we keep polluting the land?