I believe the reason as for why experimental procedures are carefully defined is because of D. The clearly defined steps allow other scientists to perform the same experiment.
Keystone species ; this is a species whose presence is critical to the composition and integrity of the community
Answer:
together, the brain and spinal cord form the central nervous system. This complex system is part of everything we do. It controls the things we choose to do—like walk and talk—and the things our body does automatically—like breathe and digest food
hope that helps
A. DNA molecules, I think
