Carbon dioxide in the atmosphere

The greenhouse effect and the importance of balancing carbon dioxide in the atmosphere.

Combustion of natural gas

The burning of methane as a chemical reaction.

Digestive enzymes

The roles of different enzymes in digestion are discussed with an overview of digestion.

Gaseous exchange in the lungs and the importance of alveoli

Gaseous exchange in the lungs and the important role played by the alveoli is explained.

How commercial growers improve crop yield

How farmers manipulate growing conditions to improve quality and yield in crops.

How oil spills damage wildlife and the environment

The Exxon Valdez oil spill demonstrates the effects of pollution on the environment.

Pollution, acid rain and the environment

How pollution and acid rain damages the surrounding environment.

Three examples of how human activity has damaged the environment

Areas around the world affected by different types of pollution.