Question

tropical rain forests support more species per unit than any other terrestrial ecosystem what is one way rain forests are important to the health of the biosphere

Answer 1

About half of the worlds plant species can be found in the rainforsets. 
Plants can convert atmospheric carbon dioxide to other carbon based compounds through photosynthesis. Rain forests are the largest carbon revisers and are responsible for most of the oxygen in the atmosphere 

Basically they take in carbon dioxide,convert it to oxygen and then release the oxygen back into the environment. Thus helping to prevent the plant from heating up.

Hope this helps out 
 

Answer 2

Answer:

The tropical rain forest covers the near-equatorial region and this region experiences a high amount of rainfall, that helps the trees of the rain forest to carry out the process of photosynthesis, by absorbing carbon dioxide in the presence of sunlight and water, and in return, it liberates oxygen and food, on which the organisms are dependent on. This tropical rain forest region is comprised of a large number of trees that supply a large amount of oxygen to all the organisms on earth.

This region also is rich in a variety of trees that produces various types of food, and these are essential for all types of organisms.

The climate in this region also is favorable because a good amount of sunlight and rainfall occurs that helps the organisms to live a healthy life.

Thus, the tropical rain forest supports a large number and variety of living species per unit area in comparison to the other terrestrial ecosystem. So, they are very important for the health of the biosphere.