What is photosynthesis in biology

What is photosynthesis in biology:- photosynthesis is an anabolic process in which complex carbohydrates are synthesized by green parts with the help of water and carbon dioxide in the presence of light. During this process green plant trap solar energy and convert it into chemical energy . This energy is stored in the form of adenosine triphosphate (ATP) are reduced nicotinamide adenine dinucleotide phosphate (NADPH). plants utilize this energy in the reduction of carbon dioxide by which carbohydrates are formed. Hence this process is also called carbon assimilation.

The photosynthesis can be defined as Photosynthesis is an anabolic process in which complex carbohydrates are synthesizes from simple substance like carbon di oxide and water in the presence of light by chlorophyllous cells of the plants and oxygen is a by products.

Earlier the mechanism of photosynthesis was represent by the following simple equation-

6CO2+6H2O → C6H12O6 + 6O2 ↑

importance of photosynthesis

Photosynthesis is considered the most important process of biosphere due to the following reasons :-

  1. in photosynthesis organic matter is synthesized by inorganic compound. About 170 million tonnes of dry organic matter is produced by this process annually.
  2. In this process atmosphere carbon dioxide is consumed and oxygen is released which is vital air for all the organisms.
  3. Green plants are called producer because the synthesize organic matter for other organisms (consumers). All the consumers depends directly or indirectly on organic food synthesized by plants.
  4. many useful photosynthetic products are obtained from plants for example fodder, fuel, timber, fibers, rubber, resin, tannins, oil etc.
  5. All the fossil fuels such as mineral coal, petroleum substance and natural gases are the products of photosynthesis of ancient plants which are the significant source of energy now a day

Site of photosynthesis

The process of photosynthesis occurs in chloroplasts. Chloroplasts are mainly found in mesophyll cells. The mesophyll cell may contain upto 300 chloroplasts. in higher plants, Chloroplasts may be oval, Spherical and discoid in shape.

Structure of chloroplast

Each chloroplast is surrounded by two unit membranes of lipoprotiens which are called outer and inner membrane These membrane are smooth and selectively permeable. inter membrane space is present between these two membranes. Two system are found inside these membranes

  1. Stroma or matrix
  2. Grana or Lamellar system

Stroma or matrix:-

An aqueous proteinaceous substance is found inside the membrane called stroma. Its 50% amount consists of soluble proteins ribosomes and DNA. It also contains starch grains and osmophilic droplets. The dark rections of photosynthesis occur in this part only Therefore the enzymes related to this rection are found in this part only.

Grana or lamellar system:-

This system is found inside the stroma and made up of numerous membranes. These membranes remain spread parallel to each other throughout the entire length of chloroplast. They are called lamellae. Each Lamella is formed of two membranes. The round flat lamellar made of unit membranes are arranged one above the other like stack of coins and gives them a special structure (Appearance) called granum (Plural-grana). Each granum has upto 5-50 such lamellae called thylakoids. A mature chloroplast usually has upto 40-60 grana which are connected to one another by intergranum lamellae. They are also called stroma lamellae or frets.