Plants are autotrophic organisms, meaning they generate a carbon energy source from inorganic components. They have adapted the capability of utilising sunlight, water and atmospheric carbon dioxide to generate energy for cell maintenance and growth.
The oxygen that we breath comes from the photosynthesis carried out by plants. Through the use of sunlight and carbon dioxide, the oxygen bound in water molecules is released into the atmosphere. During the photosynthetic process, electrons are removed from the water molecule, which is how oxygen becomes separated from the hydrogen.
Plants are able to convert the heat energy from sunlight into a usable, chemical-free energy that drives the photosynthetic process. Without adequate sunlight, plants would not be able photosynthesise and no oxygen would be released into the atmosphere.
Biological activity slows as temperatures decrease. The cellular functions required for photosynthesis slow down as the air cools, thereby slowing growth. Additionally, cold air typically contains less moisture, which can result in water loss from leaf surfaces and also can cause portions of water inside of the plant to freeze.
Plants require more than just a usable carbon source for maintaining their structure and increasing their growth potential. Through their root systems, they are able to obtain nutrients such as nitrogen, phosphorus, calcium and magnesium from the soil. Also, soil serves to stabilise plants and prevent them from falling over.
Fertilisers are frequently applied to stimulate plant growth. Certain nutrients, such as nitrogen and phosphorus are often limited in supply, which can suppress plant growth. Therefore, fertilisers give plants an additional growth boost.