Photosynthesis and Factors Affecting on Photosynthesis

Photosynthesis and Factors affecting photosynthesis

 

Photosynthesis:

In plants, algae, and some bacteria, photosynthesis is the process through which solar energy is transformed into chemical energy. The foundation of the food chain, this extremely energetic molecule supplies vital energy for a number of cellular processes.

The light-dependent processes and the light-independent reactions (Calvin cycle) are the two primary phases of photosynthesis. Let's explore each level in greater depth:

 

1. Light-Dependent Reactions:

a. Light Absorption: The thylakoid membranes of chloroplasts contain pigments that absorb light, primarily chlorophyll, in the initial stage. The green color of plants is a result of these pigments.

b. Water Splitting (Photolysis): Water molecules (H2O) split into oxygen (O2), protons (H+), and electrons (e-) in direct proportion to the absorbed light energy. The activities that follow release oxygen gas into the atmosphere, which is necessary for sustaining life on our planet.

c. Electron Transport Chain (ETC): The thylakoid membrane's many intertwined protein complexes are traversed by the water molecules' charged electrons. As electrons move from one complex to the next and release energy in the process, protons (H+) from the stroma are pumped into the thylakoid space, creating a proton gradient.

d. ATP and NADPH Formation: In response to the proton gradient created across the thylakoid membrane, the ATP synthase protein complex generates ATP. At the same time, high-energy electrons from the electron transport chain (ETC) combine with NADP+ (nicotinamide adenine dinucleotide phosphate) to create NADPH, a crucial energy carrier.

2. Light-Independent Reactions (Calvin Cycle):

Calvin Cycle, commonly referred to as light-independent reactions, is a vital component of photosynthesis in plants. These chemical processes are in charge of converting atmospheric carbon dioxide (CO2) into glucose and other organic molecules, and they take place in the stroma of chloroplasts. The Calvin Cycle, in contrast to light-dependent processes, depends on the energy carriers (ATP and NADPH) created in the preceding cycle rather than on light itself.

a. Carbon Fixation: In the stroma of chloroplasts, the Calvin cycle takes place. Carbon dioxide (CO₂) is drawn from the atmosphere and combined with the five-carbon molecule ribulose-1,5-bisphosphate (RuBP) via the enzyme Rubisco. This reaction produces a six-carbon intermediate called 3-phosphoglycerate (3-PGA), which rapidly dissociates into two different three-carbon molecules.

b. Reduction: ATP and NADPH both contribute to the conversion of 3-PGA molecules into the more energetic chemical known as glyceraldehyde-3-phosphate (G3P). These vital energy sources are generated as outcomes of the light-dependent processes, and they supply the necessary energy and electrons for this transformative step.

c. Regeneration of RuBP: It is possible to rebuild the original five-carbon complex, RuBP, using some of the G3P molecules. As more carbon dioxide needs to be fixed by RuBP in order for the cycle to continue, Rubisco must complete this step.

d. Glucose Production: In the end, the G3P molecules created during the cycle are used to create glucose and other carbohydrates, which can be kept in the plant as energy reserves.

A complex biological process influenced by many variables is photosynthesis. Numerous elements may either improve or impair the effectiveness of photosynthesis in plants. The following are important elements that have an impact on how photosynthesis occurs.

Factors affecting on photosynthesis

Light Intensity:

Intensity of light must be sufficient for photosynthesis to take place. The energy required to power the light-dependent processes, which generate ATP and NADPH, is provided by light. On the other hand, photooxidative harm can result from excessive light. The amount of light that various plant species need varies.

Carbon Dioxide (CO₂) Concentration:

The Calvin Cycle uses carbon dioxide as a raw material, incorporating it into glucose. Up to a certain point, higher CO₂ concentrations can enhance photosynthesis, but after that, other limiting variables cause the rate of photosynthesis to level off.

Temperature:

The temperature has an impact on photosynthesis. The ideal temperature ranges for enzymes participating in both light-dependent and light-independent processes. Enzyme denaturation can occur at high temperatures, and metabolic activities can be slowed down at very low temperatures.

Water Availability:

Water is necessary for the photolysis reaction of the light-dependent processes as well as for maintaining the turgor pressure in plant cells. Lack of water can cause stomatal closure, which lowers CO₂ uptake and hinders photosynthesis.

Chlorophyll Concentration and Pigment Composition:

Many pigments can create a hurdle or disturb the normal photosynthesis process. Higher Chlorophyll concentration leads to higher photosynthesis but poor chlorophyll content in plants leads to poor photosynthesis.

Nutrient Availability:

Building proteins, enzymes, and other crucial substances involved in photosynthesis requires critical nutrients including nitrogen, phosphorus, and potassium. These nutritional deficiencies may reduce the effectiveness of photosynthetic activity.

pH Levels:

Specific pH ranges are necessary for certain photosynthesis-related enzymes to work at their best. The rate of overall photosynthetic activity can be impacted by pH variations that differ from the ideal range.

Oxygen Concentration (O₂):

During the Calvin Cycle, oxygen and carbon dioxide fight for binding to Rubisco. Photorespiration, which lowers the effectiveness of carbon fixation and energy generation, can result from elevated oxygen levels.

Leaf Anatomy and Stomatal Conductance:

Gas exchange is impacted by leaf structure, particularly how cells are arranged and stomatal apertures. Effective stomatal conductance enables CO₂ entry and oxygen egress from the leaf. CO₂ uptake may be hampered by stomatal closure brought on by water stress or other reasons.

Altitude and Elevation:

Lower air pressure and less available oxygen are two factors that could affect photosynthesis at higher altitudes.