1. Water Water is the primary carrier of energy in nature. It can move at incredible speeds and create enormous pressures. This is not only true for water; electricity works on similar principles. In biology, water is responsible for the transport of materials between cells, thus assisting in the transfer of chemical signals. Water's ability to dissolve gases means that it is involved in many functions that are critical to our survival. 2. Carbon Dioxide Carbon dioxide (CO2) is the gas that plants breathe in order to extract oxygen from the atmosphere. Plants use carbon dioxide to make food via photosynthesis, but they are unable to do this without oxygen. Without enough oxygen, the plants will die. CO2 is a greenhouse gas, and many scientists believe that its concentration in the atmosphere has been increasing due to human activity. They say we should be concerned about this because it impacts climate change. 3. Oxygen Oxygen is what makes air breathable. It is the green gas that keeps us alive. When there is too much or too little oxygen in our environment, it causes problems for humans and animals. Plants need oxygen to exist. When there is too little, plants cannot survive. Too much oxygen can be dangerous for animals, though.
