Module 2 Intro

Module 2—Biosphere Equilibrium and the Impact of Humans

Lesson Summary

In this lesson you explored this essential question:

• How does the relationship between gas exchange in photosynthesis and cellular respiration influence the composition of the atmosphere?

Two biological processes—photosynthesis and cellular respiration—are hugely important to the biosphere. These processes have, over a billion years, established the balance of oxygen and carbon dioxide that all life on Earth depends on. What happens when humans try to recreate that balance, for example, when you tried to create a biosphere in a bottle? It is not easy, yet despite knowing how difficult it is to maintain a balance, people continue activities that alter the atmosphere in a variety of ways which scientists propose is causing global warming.

As you move into Lesson 3, you will see the large ecological footprint that people leave behind them as they move into the future. Should people be worried?

Lesson Glossary

anoxic: lacking free oxygen

stromatolites: sedimentary rock in oceans built from fossilized micro-organisms, such as bacteria