What is photosynthesis?
The human body needs food, water and oxygen for normal functioning. The air we breathe is twenty percent oxygen. We know that oxygen is produced during photosynthesis. However, do you know what photosynthesis is?
The following describes the mechanics of photosynthesis, its varieties and significance for our world.
Photosynthesis is the process of generating nutrients of green plants. The synthesis of nutrients from carbon dioxide occurs in chlorophylls (green plant pigments) under the influence of light. Chloroplasts, light, carbon dioxide, water and temperature play an important role in this process.
- The light involved in the process of photosynthesis is absorbed by chlorophylls.
- Chlorophylls contain chloroplasts - intracellular organoids of the green pigment. Under the influence of sunlight, chloroplasts draw water from the soil, dividing it into hydrogen and oxygen.
- Two processes occur during photosynthesis. Photosynthesis in leaves begins after they absorb water and carbon dioxide.
- Light energy is collected in special compartments of chloroplasts, called thylakoids, and then divides the water molecule into oxygen and hydrogen.
- Some of the oxygen is produced in the atmosphere, and some goes to the breathing of the plant. After that, carbon dioxide in pyrenoids (protein granules surrounded by starch) is mixed with hydrogen and forms sugar molecules. This reaction also produces oxygen.
- By mixing sugar with nitrogen, sulfur and phosphorus extracted from the soil, green plants produce starch, fats, proteins, vitamins and other complex compounds necessary for life.
Although in most cases photosynthesis takes place under the influence of sunlight, artificial light can also take part in it.
Types of photosynthesis
It makes sense to talk not about different species, but rather about different mechanisms of photosynthesis. The fact is that before the 60s. last century, scientists were only aware of one mechanism for fixing carbon dioxide - by the C3-pentose phosphate pathway. However, recently a group of Australian scientists was able to prove that in some plants carbon dioxide reduction occurs in the C4-dicarboxylic acid cycle:
- In plants with the C3 reaction, photosynthesis most actively occurs under conditions of moderate temperature and light, mainly in forests and in dark places. These plants include almost all cultivated plants and most of the vegetables. They form the basis of the human diet.
- In plants with the C4 reaction, photosynthesis most actively occurs under conditions of high temperature and light. Such plants include, for example, maize, sorghum and sugar cane, which grow in warm and tropical climates.
- The plant metabolism itself was discovered quite recently, when it was possible to find out that in some plants that have special tissues for water storage, carbon dioxide accumulates in the form of organic acids and is fixed in carbohydrates only a day later. Such a mechanism helps plants to save water.
The value of photosynthesis for our planet
Previously, there was no oxygen on our planet Earth. We owe its appearance to photosynthetic cells. Thanks to them, oxygen was actively produced in the atmosphere of the planet and oxygen breathing appeared - the most profitable way of energy metabolism.Oxygen has caused the formation of a protective ozone layer around the Earth, which protects the planet from harmful solar radioactive rays. This allowed living organisms out of the ocean to land, which predetermined the further evolutionary path of development of living beings.
But not only the production of oxygen is important in the process of photosynthesis. It is also important that plants absorb carbon dioxide from the atmosphere. An excess of carbon dioxide can cause a greenhouse effect, which would have a very negative impact on all living organisms of our planet. Over the past few decades, the carbon dioxide content in the atmosphere has increased. This was due to the industrial revolution and further technical progress. Scientists continue to argue what consequences this will lead to, but already today they urge the world community to pay attention to this problem before it is too late.