Light Reaction: Working & Photosynthesis

Ans: Photosynthesis is usually known as a physic-chemical process that, by large, prefers using light energy for synthesising nutrients and organic compounds vital for their survival. In a nutshell, what commonly happens is that the chloroplasts align against the walls of the mesophyll cell to acquire as much incident light as possible to synthesise nutrients. The process of photosynthesis is usually dissected into two forms: light reaction and dark reaction.

Ans: Light reaction is a chemically driven process involved in photosynthesis that is responsible for converting the energy of the sun into chemical energy in the form of NADPH and ATP. Light reactions are known to undergo multiple steps. The procedure includes a series of chemical reactions, often called light-dependent reactions. The light-dependent reaction usually begins taking place in the chloroplast of the mesophyll cells of the green leaves.

Ans: Following are the differences:

Ans: The following are the steps of light reaction:

• The initial step includes chlorophyll absorbing the energy emitted from the sunlight and converting it to chemical energy in the appearance of electron charge carrier molecules.
• This process is held inside large protein complexes, called Photosystems, which can be forked into PSI and PSII.
• The excited chlorophyll, afterwards, gives up electrons. And to compensate for it, water is cleaved into H+ ions, electrons and O2.
• The lost electrons subsequently enter ETC and combine with NADP+, reducing it to NADPH.
• Then, the H+ ions form a positive gradient and join with ADP to produce ATP. Upon which, water gets retained.

Ans: Photosynthesis in higher plants usually involves more than one process. In the process of Photosynthesis, chloroplasts usually align against the walls of the mesophyll cell to acquire as much incident light as possible. Photosynthesis generally has a green pigment called chlorophyll, which goes on to produce oxygen, which is a by-product. There are four pigments incorporated in the process of photosynthesis, which are

• Chlorophyll a
• Chlorophyll b
• Xanthophylls
• Carotenoids

Ans: The electron transport chain (ETC) is a constant series of four consecutive protein complexes that involve multiple redox reactions. It forms a layer of electrochemical gradient that further steers the formation of ATP in a whole system, referred to as Oxidative Phosphorylation.

• These electron transporters, in general, are embedded against the inner membrane of mitochondria.
• It further steers electrons from NADH and FADH2 to the molecular oxygen.
• It occurs in mitochondria, with processes involving respiration and photosynthesis.

Ans: The primary step in the process of photosynthesis is to absorb photons by antenna molecules. The Antenna Complex is known to be a light-absorbing membrane that has a chain of proteins and chlorophyll molecules aligned in the thylakoid membrane of plants, alongside cyanobacteria as well, that allows transmission of light energy to a single chlorophyll molecule in a reaction centre of photosystem which are large protein complexes. The antenna complex has been around with several ranging pigments, like chlorophyll a and b in plants, chlorophyll c in various algae, and bacteriochlorophyll a, b, or c in bacteria.

Ans: Photosystems are known to have pigment molecules. Generally, photosystems are the operating units of the process involved in photosynthesis. Quite apparently, it is shaped by large complexes of proteins and light-absorbing molecules that synthesise light and act as a pivotal unit in light reactions.

• Photosystems, by large, are constituted of pigment molecules.
• As a general idea, chlorophyll is one of the fundamental pigments which partakes in the light reaction method, actively referred to as Photosynthesis.
• Time and again, these accessory pigments comprise carotenoids.

Ans: Light Reaction Equation is summarised by three equations:

• When water is exposed to oxygen then oxidation of water take place.

2H₂O→O₂+4e⁻+4H⁺

• Reduction of NADP.

2NADP⁺+4e⁻+4H_⁺→2NADPH+2H⁺

• Next is synthesis of the ATP molecules

ATP→ADP+Pi

The final involved at the light reaction is as follows:

2H2O+2NADP⁺+nADP+nPi+hv→O2+2NADPH+2H⁺+nATP

Ans: Calvin Cycle is a light-dependent reaction that converts carbon dioxide and hydrogen carrier into glucose. It takes place in the stroma of plant cells. The stroma is located outside the thylakoid membrane of the chloroplasts.

• Calvin Cycle is carried out during the day when NADP and ATP are present in abundance.
• It stores malic acid inside the vacuoles during the night.
• The cycle generates the triose phosphates, 3-phosphoglycerate, glyceraldehyde-3P, and dihydroxyacetone phosphate.
• The compounds are further synthesised into hexose phosphates fructose-1,6-bisphosphate and fructose 6-phosphate.

Ans: Dark Reaction is a type of light-independent reaction which also goes by the name carbon fixation cycle. It takes place in the chloroplast's stroma, where the energy used during the light reaction is utilized. 

• In this first plant captures the carbon dioxide from the atmosphere.
• The stomata capture the carbon dioxide.
• In this process, the hydrogen of NADPH combines with CO2 molecules.
• Glucose is the final product obtained in the dark reaction.

Ans: Chlorophyll is a type of pigment that is responsible for imparting green colour to plants. It also helps the plant produce the required food during the process of photosynthesis. It absorbs energy with the help of plants from light. It is divided into two categories, namely chlorophyll a and chlorophyll b. It absorbs the maximum amount of light in the blue portion of the electromagnetic spectrum.