Raw materials for photosynthesis

Photosynthesis is a process in which there is a synthesis of bio molecules e.g. sugar molecules. Therefore, for the synthesis of bio molecules raw material is required by the plant. Raw material for the photosynthesis is carbon-dioxide, water, sunlight and chlorophyll.

Carbon Dioxide:- Carbon dioxide present in atmosphere is normally obtained by the plants through stomata. Carbon dioxide enters into the plant by simple diffusion. Small quantities of carbonates are also absorbed by the plants from soil. Hydrophytes ( aquatic plants ) gets carbon dioxide from the water in the form of bicarbonates.

                                                                     Photosynthesis 

Water:- Water plays very important role in any physiological reactions. ( physiology is the study of functions in living things ). Van Niel proved that some bacteria used H2S as a reducing power while working on photosynthetic bacteria. Therefor, in these bacteria instead of evolution of oxygen sulphur globule accumulated as a waste material.


                                  6CO2  +  12H2O        --------------     C6H12O6   +    6H2O   +   12S

Robin Hill illuminated the isolated chloroplast to sunlight and even in the absence of CO2 he found that chloroplast evolved oxygen during photosynthesis.

                                    2A ( hydrogen acceptor)  +  2H2O   ----------------  2AH2  +  O2

These hydrogen acceptor are also called Hill Oxidants and because oxygen is evolved during the illumination of chloroplast to sunlight even in the absence of CO2 is called Hill Reaction.
Ruben et al ( 1941 ) proved that oxygen evolved during photosynthesis comes from H2O by suspended Chlorella in water having heavy isotope of oxygen O18 .

                                                                           Light
                     6CO2  +  12H2O18                  ----------------               C6H12O6  +  6H2O  +  6O18
                                                               Chlorophyll, enzymes


Light:- Light is the visible part of electromagnetic radiations. Visible light have the wavelength from 390 to 760 nm. This is made up of different colours of wavelength starting from violet to red light. These are violet ( 390-430nm), blue or indigo ( 430-470nm), blue green ( 470-500nm), green ( 500-580), yellow ( 580-6800, orange ( 600-650), red ( 650- 760). This is also called VIBGYOR. Photosynthesis used wavelength from 400-700nm. These radiations are called photosynthetic active radiatios ( PAR ). Blue and green light is the most effective radiations for photosynthesis. Maximum absorption of these wavelength of light takes place during photosynthe.

Chloroplast :- Already mentioned in detail. This organelle contains photosynthetic pigments so plays vital role in photosynthesis.
           

Reproduction

Reproduction is a biological process in which organisms produces their own kind of individuals. Reproduction is the most typical character of living beings. In other words it is the process in which species maintains their survival on this earth by producing the young ones of the same species.

Purpose of reproduction:-
i) Reproduction maintains the continuity of species.
ii) It is the process in which any population able to maintain the young, adults and aged individuals.
iii) Reproduction helps to bring the variations among any specie which helps that specie for adaptation and evolution for changing surrounding conditions.
iv) Life is possible on this earth because of reproduction.

Types of Reproduction:- Basically there are two types of reproduction found in the living organisms. These are
   
               a) Asexual Reproduction
               b) Sexual Reproduction

a) Asexual Reproduction:- It is the reproduction in which there is only single parent involved in the process or without the fusion of male and female gametes ( involvement of male and female gametes occurs in the sexual reproduction). In this type the organisms produced will be the exact copies of parent.  These individuals are called clones because they are genetically and morphologically similar to their parent.
Main features of asexual Reproduction
i) There will be a single parent.
ii) There will not be a gamete formation.
iii) fertilisation will be absent.
iv) No meiosis will takes place only mitosis will be present.
v) Because there is no fusion of the gametes of two different parents so no variation or daughter individuals are genetically identical to the parent.
vi) Multiplication occurs rapidly.

Asexual reproduction is normally the character of unicellular organisms like monerans and protists and in plants and in certain animals.

b) Sexual reproduction:- It is a reproduction in which new individuals are formed through the formation and fusion of male and female gametes. This process is also called amphimixis ( both parents's gametes are mixing together). Actually sexual reproduction has four main steps:-

i) Formation of gametes through the division of meiosis. this is called gametogenesis or this is the formation of haploid cells. ( 1N )
ii) Fusion of two gametes forming the diploid cell ( 2N ) zygote. This fusion is called fertilisation.
iii) Repeated mitotic divisions of zygote for the formation of embryo.
iv) Growth of the embryo into full individual.

Main features of Sexual reproduction:-
i) Two parents are involved therefor, it is usually biparental.
ii) There is always formation of gametes.
iii) It involves both meiosis and mitosis.
iv) New individuals formed will be different from their parents.
iv) Multiplication is not so rapid as in case of sexual reproduction.

Photosynthesis

Photosynthesis is an enzymatic controlled anabolic process in which there is a synthesis of organic compounds inside the chlorophyll containing cells from the water and CO2 in the presence of sunlight.
                                                           OR
Photosynthesis is a process in which green plants makes their own food in the presence of sunlight from the H2O and CO2 with the help of chlorophyll molecules.
                                                           OR
Photosynthesis is a process in which there is a conversion of light energy into chemical energy.   

                        6CO₂ + 12H₂O + Light Energy → C₆H₁₂O₆ + 6O₂ + 6H₂O

 The function of water is to provide hydrogen for the synthesis of organic compounds and liberation    of oxygen during the process. 
 The organisms which has the ability to perform photosynthesis are called photoautotrophs. All green plants, cyanobacteria, algae and many protists are photoautotrophs. 

Importance
i) Photosynthesis is the only process in which synthesis of organic molecules from the inorganic raw material is possible.
ii) Photosynthesis plays very important role in releasing oxygen into atmosphere to compensate for O2 using through the process of respiration. It helps in maintaing the balance between O2 and CO2 level in the atmosphere.
iii) All heterotrophs are depends on photoautotrophs for their food requirements. 
iv) All types of fossil fuels like coal, petroleum and natural gas are the results of photosynthesis.
v) Many plant products are very useful like timber for making furniture, doors and windows, rubber, resins, drugs, oils, fibres etc.
vi) Crops productivity is directly dependent upon the rate of photosynthesis.