Three reasons a species could become extinct include, deforestation, being overhunted, not enough food available.
Here is the equation for cellular respiration if that helps.
Answer:
The position it holds in the food chain
Explanation:
A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves.
The answer is once underwater.
Heart, kidneys, intestines, thymus, gonads, and adipose tissue.