Before examining how photosynthesis works, we need to understand just how important this process is for life on Earth. Let us consider the results of this process:
Photosynthesis and oxygen
In carrying out photosynthesis, plants absorb the carbon dioxide in the air (CO2), a gas that human beings cannot use, and break it down into oxygen (O2). Oxygen, which we take into our lungs when we inhale and which is essential to life, is the main product of photosynthesis. Some 30% of the oxygen in the atmosphere is produced by terrestrial plants, and the remaining 70% by single-celled algae and marine plants also capable of photosynthesis. The striking thing here is that while human beings continually destroy plants on land, they are unable to eliminate those in the oceans—their main source of oxygen—at the same rate. The fact that different living things capable of photosynthesis have been created allows us to possess a source of oxygen that is never completely decimated.
Photosynthesis and nutrients
We humans receive all the nourishment we need either directly from plants or else from herbivorous animals. Sunlight is simply a source of energy; but its raw form is not that practical. It is impossible to consume this energy, or to use it or store it directly in the body. Therefore, solar energy needs to be converted into another, usable form of energy—which is what photosynthesis does. By means of this process, plants turn solar energy into a stored form they can use at some later time. Using solar energy, the photosynthetic reaction centers in leaves converts the carbon dioxide in the air into starch and other high-energy carbohydrates. The O2 released after carbon dioxide has been used is released into the atmosphere. When the plant later requires energy, it uses the energy it has stored in these carbohydrates. Living things that feed on these plants, in turn, meet their own energy needs through the carbohydrates stored in them, by way of photosynthesis.
As we shall be seeing, photosynthesis is an exceedingly complex process. The fact that all living things acquire the food they need to live as a result of such a complex process is the work of the infinite knowledge and wisdom of Allah:
O humanity! Remember Allah’s blessing to you. Is there any creator other than Allah providing for you from heaven and earth? There is no Allah but Him. So how have you been perverted? (Surah Fatir: 3)
Photosynthesis and energy
Your car engine runs on what was once solar energy. Jet planes fly thanks to what was once solar energy. You are using what was once solar energy even as you read these lines.
The first thing that comes into your mind as you read this will be that your car actually runs on gasoline and that jetliners use aviation fuel. You will imagine that you acquired the energy to read these lines from the last meal you ate, not from solar energy. The fact is, however, that both gas and the meals you eat, and even the wood and coal we burn for warmth, all contain energy obtained from the Sun—via photosynthesis. How?
Plants that stored solar energy in their bodies millions of years ago by means of photosynthesis, and animals that ate these plants, gave rise to the petroleum with which we are familiar, underground and under high pressure, after a period of millions of years. Coal and natural gas came into being in the same way. In short, the solar energy stored in plants thanks to photosynthesis was placed at our disposal after millions of years had passed.
Similarly, the energy you obtain from the food you eat is simply the solar energy stored by plants. The energy you obtain from animal foodstuffs is also the energy those animals obtained from plants. The source of energy is always the Sun, and the system that makes this energy useable by human beings is always photosynthesis. You cannot acquire the energy you possess by means of any system other than photosynthesis.
Photosynthesis and side products
Wood is a very important material used not just as fuel but in many fields, including construction. Paper, cotton and other natural fibers, for instance, consist of cellulose produced almost entirely by photosynthesizing plants. Even wool depends on the energy sheep obtain from grass, and photosynthesis. Solar energy, transformed by photosynthesis, is the source of countless vegetable, animal and organic side products.
Photosynthesis and the environment
Living things constantly increase the carbon dioxide in the air and the air temperature. Millions of tons of carbon dioxide are released into the atmosphere every year as a result of the respiration of human beings, animals and micro-organisms in the soil, not to mention burning of fossil fuels. Moreover, the amount of carbon dioxide released into the atmosphere from fuels consumed for heating purposes in factories and homes and used in transport also reaches billions of tons. According to one study, an increase of 42 billion metric tons in the carbon dioxide has been seen in the atmosphere in the last 22 years. One of the main causes of this rise is the fuels consumed and deforestation. The rise in carbon dioxide caused by fuels over the last 22 years is 78 billion metric tons.
Unless this rise is compensated, there will be terrible ecological imbalances. In such an event, the amount of oxygen in the atmosphere will fall to very low levels, and the Earth’s temperature will rise, as a result of which the ice caps will melt. Therefore, some low-lying regions will be flooded, while others will turn into deserts, and all life on Earth will be endangered. Yet that will not be the case, because carbon dioxide is constantly consumed and oxygen released in the process of photosynthesis carried out by plants and micro-organisms. Thus the equilibrium in nature can persist. While there has been a rise of 78 billion tons in carbon dioxide caused by fuels, the level remaining in the atmosphere is 42 billion tons. This excess CO2 is to a large extent cleaned up from the atmosphere by way of photosynthesis and the oceans.
The Earth’s temperature is fixed within a specific range. Wide temperature fluctuations do not occur, because green plants also ensure temperature balance.
Photosynthesis ensures the continuity of these balances, which are of such vital importance for life on Earth. Also, there is no other mechanism for the preservation of the level of oxygen in the atmosphere.
In conclusion, it is clear what a great miracle photosynthesis is, and how closely it impacts on our lives. This flawless system was discovered only in the last century. Studying those phases of this mechanism, full of astonishing miracles that have only recently been understood, will increase our appreciation for the infinite knowledge of Allah.