Answer:
Ozone layer... pollution
Explanation:
The ozone layer is a layer in the atmosphere which provides a barrier between harmful UV rays and the Earth. However, pollution is quickly depleting the layer which in turn creates a higher risk of skin cancers and other conditions caused by harmful UV rays.
The root cap is a small structure but one that serves a very important function for a plant. Protecting the root apical meristem allows for primary growth in the root, which paves the way for lengthening of the plant as well as cell specialization.
Organisms are classified and divided in a community based on the modern classification system that was published by Carolous Linnaeus in the 18th century.
This criteria is also known as the Linnean system of classification, where the organisms are classified according to the following: Species, Genus, Family, Order, Class, Phylum and Kingdom.