Put the elements into the gaps

Read the text and fill in the gaps. There are two extra words.

• environment
• purposes
• endangered
• source
• dangerous
• produce
• provide
• chemicals

As people change the [ ] they live in, plants and animals in these regions can become [ ]. Different specialists called plant taxonomists and plant ecologists find and describe new plant species, especially in such biologically abundant places as tropical rain forests. Rainforests are important for the whole planet, but the plants growing there could also be used. It is possible that an unknown plant will become a great food [ ]. Plants are also potent chemical laboratories. Many of the chemical elements that they [ ] are vital to human health. Plants [ ] us not only with food but also make raw materials to manufacture paper, fabrics, medicines, building materials, and many other products. People who study plants are called botanists. They examine the [ ] produced by various plants to explore new ways of using them. For example, a medicine derived from some plants is efficient in treating certain diseases.