Photosynthesis is a concept that most people have heard about from a very young age. We all know that plants use sunlight and convert it into energy, but this is really just the basics of what happens during photosynthesis. Thus, in my essay, I’m going to dig deeper into it.
First of all, it should be noted that there are two types of photosynthesis: oxygenic photosynthesis and anoxygenic photosynthesis. Oxygenic photosynthesis produces oxygen and is used by plants and algae to convert photons from sunlight into chemical energy. In this process, energy from the sunlight transfers electrons from water into carbon dioxide. This ultimately produces carbohydrates, which is what makes the plant grow, and oxygen. In this process, CO2 gains electrons while oxygen loses electrons and becomes oxidized. The process of oxygenic photosynthesis acts as a counterbalance to another process that plants go through, called respiration. It balances out respiration by taking all the carbon dioxide that is produced by other living organisms and putting oxygen into the air. The process of oxygenic photosynthesis can be written as a chemical equation. It is written as shown: 6CO2 + 12H2O + Light Energy → C6H12O6 + 6O2 + 6H2O. This means that six molecules of carbon dioxide combined with 12 molecules of water and the use of light energy are converted into a carbohydrate and six molecules of oxygen and water are released into the air (Vidyasagar, 2018).
There are three basic segments in the process of photosynthesis: carbon fixation, reduction, and regeneration. In carbon fixation, six molecules of CO2 are put into the cycle. Then, it is split into two 3PGAs. Subsequently, 6ATP is converted into 6ADP and 6NADPH is changed into 6NADP+. Next, the process of reduction is started. One molecule of G3P goes to make sucrose or other sugars. The remaining 5G3P are recycled and go back through the process. In the process of regeneration, there are 3RU5P, and 3APT is converted to 3ADP, and the process starts again.
Parts of photosynthesis are reliant on sunlight, and some are not. Both light-dependent and light-independent reactions happen in the chloroplasts of plants. But more specifically, light-dependent reactions happen in the thylakoid and light-independent reactions occur in the stroma. Light-dependent reactions are dependent on light, unlike light-independent reactions, which don’t need light. This gives a false pretense that light-independent reactions happen in the dark, but that is incorrect. Both reactions happen in the light. Light-dependent reactions happen when a photon from sunlight hits a reaction center in a chloroplast, and chlorophyll or another pigment releases an electron. The electron that was released in this process travels through the electron transport chain. This is needed to create ATP and NADPH. The hole that was left by the released electron is filled with an electron that is stolen from the water. As a result of this process, oxygen is released into the air. The reason that this is called a light-dependent reaction is that the energy of light, or photon, is needed for the cycle to begin. Light-independent reactions happen when CO2 is reduced and carbohydrates are produced. This action needs ATP to happen and is taken for the electron transport chain.
PSⅠ and PSⅡ are different photosystems. Different photosystems, like these, contain different kinds of chlorophyll in their reaction centers. In photosystem I (PSI), chlorophyll has a maximum absorption of 700nm, while in photosystem II (PSII) the maximum absorption is 680nm. The main function of these photosystems is to collect and trap solar energy and convert it into ATP. To achieve this, they have to work together. The process of the electron transport chain in photosynthesis starts when PSII absorbs light (energy) and passes it on to its reaction center. When it absorbs light, an electron is lost. This makes it oxidized, and because of this, the water molecule splits into oxygen and hydrogen, and the oxygen is released into the air. In the procedure of water splitting, electrons are made that replace the lost electron from the reaction center. These electrons are passed to the reaction center of PSI, through the electron transport chain. During this process, ATP is formed and stored. The same process happens to create NADPH, except in PSI electrons are borrowed from PSII.
Photosynthesis has many different essential parts that influence the rate at which the process happens: light intensity, temperature, carbon dioxide, water, minerals, and other internal factors (Bassham & Lambers, 2019). Light intensity and temperature affect photosynthesis because the amount of light intensity determines how quickly it goes. It is relatively independent of temperature, but temperature also plays a small role in how quickly it goes. As the light intensity increases, the rate becomes saturated. If there is too much light intensity, stages in the light-independent reaction are affected and can’t go as quickly. There has to be just the right amount of light intensity, otherwise other stages of the operation will be affected. Carbon dioxide is also an important factor in how photosynthesis occurs. CO2 affects the dark stages (light-independent stages) because it promotes the creation of organic compounds. An increase in carbon dioxide in the air could affect plant growth because it increases global temperatures, causing less precipitation. This will affect photosynthesis because it will make fewer water molecules for the plant to get food. Water affects the rate of photosynthesis more indirectly than the rest of these elements. If there is no water in the soil, the plant can’t absorb CO2 from the air, putting a damper on photosynthesis. Minerals like manganese and copper change the rate of photosynthesis because they are components of chlorophyll and other pigments. Increasing or decreasing these minerals slows down or quickens the rate based on the amount of each. Every plant is adapted to external climate and environmental factors. The plant is adapted to the normal conditions of the surrounding habitat. Certain enzymes and amounts of chemicals are balanced to fit the environment. Changes in the environment affect the internal factors of the plant. For example, if the amount of carbon dioxide in the air was doubled, the plant would increase the rate of photosynthesis, but after a few days, it would drop back down to the original rate or lower. This would be because the plant produced more sugar than it needed. Another factor that could influence the rate of photosynthesis would be electricity. Similar to how heat can affect the rate of photosynthesis, adding electricity may also speed up the rate of photosynthesis. Research reported in the journal Nature has shown that chemical reactions can be quickened using electricity (2016). Photosynthesis, being a chemical reaction, also may be able to be sped up using electricity if this is true.
Photosynthesis is a very complex reaction that is dependent on many different factors that help a plant grow. Photosynthesis itself is only a part of how a plant grows and functions. Photosynthesis is a process that helps plants grow, more or less keeping them alive. It is an important procedure that has to happen. But it takes time.