6. Lion
7.raccoon
8.rat
9. A keystone is a organism that helps define the entire ecosystem, and if the species were to disappear from the ecosystem no other species would be able to fill its ecological niche the ecosystem would be forced to radically change allowing new and possibly invasive species to populate the habitat.
Answer:
Perform different functions for the organisms
Explanation:
1-Stem cells can differentiate into other specialized cells.
2-Specialized cells are more complex.
3-Specialized cells usually do not reproduce
Carbon accumulates oxygen