An ecosystem that is not sustainable can break down when a natural disaster occurs. this can lead to organisms in the ecosystem either leaving the area or dying off. increased biodiversity results in a more sustainable ecosystem because — a) a greater number of plant species means that there is less barren land b) a greater variety of species present allows more organisms to adapt after changes occur c) the transition area between two ecosystems is narrower d) there are fewer species to be affected by environmental stresses

The correct answer is: B) a greater variety of species present allows more organisms to adapt after changes occur  

Biodiversity refers to variation at the different levels: genetic, the species, the ecosystem.

When there is high biodiversity in an ecosystem this means that there is a great variety of genes and species in that ecosystem. Ecosystem with such variety is capable to carry out natural processes and to adapt to changes that occur (there will be more species involved in food webs, more plants included in biogeochemical cycles and more genes available for succession and evolution).

they deliver oxygen to the blood