They use energy from sunlight to change carbon dioxide and water into sugars, known as food substances. Green plants can only make food when they have light. During photosynthesis the plant takes in carbon dioxide to help produce food. It is really important for the air to be clean. Therefore, any smog or air pollution can block the light of the sun and slow down the production of food and eventually killing the plant.
Water is one of the most important resources for all life processes on earth.
There is no known living thing that can exist without water. Water is needed by plants to keep growing. It is used to carry the moisture up to the leaves and then carry food produced in the leaves back down again to the roots. Water acts as the main transportation system for the nutrients needed for plants to grow and live. Plants grow anywhere there is space to grow.