The term you're referring to which scientists implement to describe "different forms of life on Earth" is perhaps "Organism".
The negative impact humans could have on an ocean ecosystem is pollution, which can lead to a mass extinction on the wildlife.
The contractions of the heart is what creates out blood to pulse through out body and is the basis of our blood pressure; which means this statement is TRUE.
The systolic number (top) of the blood pressure is our heart physically pushing the blood out of the heart and to the rest of the body.
The diastolic number (bottom) of the blood pressure our heart at rest when it has just finished with one pump.
It is known as a concentration gradient which in diffusion will always flow from ares of high concentration to areas of low concentrations
So i believe the answer to this is A.
