Natural Cycles Review part 2

Match it! Select the correct answer from the pull down...Good luck!

The cycling of chemical elements through the living and nonliving parts of an ecosystem is

Nitrogen is absorbed by plants. Plants use nitrogen to make important plant _______________________.

Nitrogen molecules make up _______________________ of the earth's atmosphere.

A swelling on a plant root that contains nitrogen-fixing bacteria is

Bacteria in soil and in the roots of ____________________________ perform nitrogen fixation.

________________________ release nitrogen back into the soil. They do this by breaking down the material in dead organisms and their waste products.

What are two ways in which cutting down the trees in a forest affect the ecosystem?

The brown smog produced when air pollutants react with sunlight is