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What Is Photosynthesis?

Photosynthesis is a chemical process that converts carbon dioxide into carbon compounds using light energy, usual energy from sunlight. This process is carried out in specific plant cells from inorganic matter.

What is photosynthesis?

The process of photosynthesis occurs in plants, algae, and some groups of bacteria. In these photosynthetic processes, light energy is transformed into stable chemical energy. However, not all organisms that use light as a source of energy photosynthesize.

This process reduces the amount of carbon dioxide (CO2) in the atmosphere in a natural way. It is of crucial importance for life on Earth.

Today, the average rate of energy capture by photosynthesis globally is almost 130 terawatts (TW). It is about eight times the current power consumption of human civilization.

What Is the Chemical Reaction of Photosynthesis?

With chlorophyll molecules' mediation, solar radiation will convert carbon dioxide and water into glucose molecules during photosynthesis. The process converts six CO2molecules and six H2O molecules into a glucose molecule (C6H12O6). Glucose is a fundamental sugar for the life of the plant.

What is photosynthesis?Photosynthesis is the primary process of production of organic molecules from inorganic substances.

The reaction formula is as follows: 6 CO2 + 6 H2O → C6H12O6 + 6 O2

What Are the Phases of Photosynthesis?

Chlorophyll photosynthesis, also called oxygenic photosynthesis, is carried out in stages in two phases:

Light-dependent Reactions

The light phase or light-dependent reaction is when the plant converts solar energy into chemical energy. Chlorophyll and other photosynthetic pigments such as carotene absorb light. The reaction breaks up a water molecule releasing oxygen.

The chlorophyll is the component of the blade centralizing the power light on the reaction center. It contains chlorophyll α and transforms it into chemical energy in electrons excited that will transport a chain of electrons. These systems are a set of chlorophyll molecules with electron transporting molecules.

Light-independent Reactions

The dark phase is a set of reactions without light (not necessarily at night). During this phase, the plant converts carbon dioxide and other compounds into glucose.

These dark reactions take the light phase products, mainly ATP and NADPH, and carry out more chemical processes.

Photosynthetic organisms need water to make NADPH. The system brokes the water molecules and also releases electrons.

The electrons must travel through particular proteins stuck in the thylakoid membrane. Firstly, they go through the first particular protein and down the electron transport chain. Then electrons pass through a second one.

The dark phase reactions are carbon fixation and the Calvin cycle.

Carbon Fixation

The carbon fixation is converting inorganic carbon (as CO2) in organic compounds by living organisms.

Organisms that grow by fixing carbon are called autotrophs. Autotrophs include:

  • Photoautotrophs synthesize organic compounds using the energy of light.

  • Lithoautotrophs synthesize organic compounds using the energy produced by inorganic oxidations.

The heterotrophs are organisms that grow using the carbon was set in organic compounds by autotrophs. Heterotrophs use organic compounds to produce energy and to build body structures.

Calvin Cycle

The Calvin cycle is a set of biochemical reactions in the stroma of the chloroplasts of photosynthetic organisms. Initially, it was thought that they took place with no light. Later, it was concluded that they were independent of the presence or lack of light. At present, we know that they need light to be carried out.

Elements Involved in Photosynthesis

The most important external factors involved in the performance of photosynthesis are:

  • Temperature: Each plant species has a temperature range in which it feels most comfortable. Within this range, the efficiency of the process varies due to an increase in the mobility of the molecules.

  • Carbon dioxide concentration: the efficacy rises in the same way that the CO2 in the air.

  • Oxygen concentration: the higher the oxygen concentration in the air, the lower the photosynthetic performance. This variation is due to photorespiration processes.

  • Luminous intensity: the higher the luminous intensity, the higher the performance, up to exceeding certain limits. Once the light exceeds these limits, irreversible photooxidation of photosynthetic pigments occurs.

  • The lighting time: some species have higher photosynthetic production than the number of hours of light.

  • Water shortage: in the absence of water on the ground and water vapor in the air, its performance decreases. If the plant detects a lack of water, it closes the stomata to avoid drying it out. The counterpart is that this self-protection system hinders the entry of carbon dioxide. Furthermore, increasing the concentration of internal oxygen triggers photorespiration.

  • The color of light, the conversion rate, depends on the light's chlorine and the species.

Does Sunlight Influence the Color of a Plant?

The chlorophyll in the plant absorbs the red and blue light much more readily than the green light. Sunlight is very rich in red light photons. Even though it is less reach in blue photons, which are more energetic. Photons of intermediate energy, green in hue, are not abundant.

The pigments absorb the part of the most abundant solar spectrum (blue and red light). However, plants reflect green light, which is why we perceive the leaves of plants green colored.

What Influence Does Photosynthesis Have on Climate Change?

Photosynthesis allows reducing the amount of carbon dioxide in the atmosphere in a natural way. Carbon dioxide is a greenhouse gas. The presence of too high levels of this type of gas in the air prevents heat from escaping.

On the other hand, especially the large forest areas, the plants do not stop absorbing this extra carbon dioxide. For this reason, photosynthesis is a natural process that contributes to making the problem of climate change bigger thanks to light energy from the sun.


    Published: August 24, 2018
    Last review: October 6, 2020