All of the living and non-living things in a particular area: biodiversity
The total variety of organisms that live in the biosphere: species
A group of organisms that breed and produce offspring that can breed:
All of the living things in a particular area:

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.