Describe the general diversity of species on Earth in terms of relative numbers and types of organisms. Compare known numbers to estimates

1.2 million plants and animals

Explanation:

The living organisms have been grouped into two kingdom  

a)Plants

b)Animal

Earth has enormous varieties of living species ranging from microscopic bacterias to huge animals like elephants, rhinoceros, from water plants and animals to terrestrial plants and animals , from autotrophic to heterotrophic organisms, from forest biome to desert biome etc.

In totality, there are 8.7 million species of plants and animals on earth. But till today only 1.2 million species have been identified and described.  

the tricuspid valve is present between right atrium and right ventricle