The importance of photosynthesis
Without plants, life as we know it would not exist on our planet. Green plants play a vital role in the following areas.
During photosynthesis plants take in carbon dioxide and give off oxygen as a by-product. Photosynthesis can therefore be considered as the reverse of respiration. Without green plants performing photosynthesis there would be no way for nature to replace all the oxygen being consumed in processes such as respiration and combustion. Furthermore the levels of carbon dioxide in the atmosphere would increase. Thus, the balance of atmospheric gases is kept stable by photosynthesis.
Green plants are called producers because they produce all their own food from the raw materials around them via photosynthesis. Animals and humans on the other hand are consumers and all the food they eat comes directly or indirectly from plants. Most of the world’s population obtains more than 80% of their food directly from plants, for e.g. rice, potatoes, wheat, corn etc. The remaining source comes from animals and these animals are part of the food chain which always begins with plants.
Many plants have cells which are long and thin with thick cell walls. These properties allow the cells to form fibres, which can be spun and woven into fabrics. Examples of these include the cotton plant used to make cotton and the flax plan used to make linen.
Plants contain a vast range of chemicals which are extracted and used in the production of medicines. Aspirin the drug used as a pain reliever and to reduce blood clotting in heart patients is derived from salicylic acid, a chemical extracted from the bark of the willow tree. Much stronger pain killers (analgesic drugs) such as morphine and codeine are produced from opium, the dried sap derived from the seeds of the poppy plant.
To date the number of plants tested for medicinal properties number only in their thousands. There are still a vast number yet to be tested including many of the species sourced from the tropical rainforests. The unknown medicinal properties of these plant species adds to the importance of protecting natural habitats such as rainforests.
Wood for use as a building material, a fuel for combustion and in the manufacture of paper is sourced from trees.
Many plants produce chemicals as a defensive mechanism to protect them against attacks from pests. These chemicals can be extracted from the plants to produce natural pesticides to protect crops and plants.