Oxygenated carotene is called xanthophyll. Its chemical symbol is C40H56O2. Among the xanthophylls are lutein in green plants, lycoxanthin in tomatoes and zeaxanthin in Bhutra.

Carotene is an unsaturated hydrocarbon compound. Its chemical symbol is C40H56O. It is of four types. Carotene a, b, c and d. It absorbs blue-violet light (449-478nm) the most. Color diversity of carotene is most interesting. Green carotene is found in avocados, red in tomatoes, reddish orange in carrots and yellow in various flowers.

Orange carotene and yellow xanthophyll together are called carotenoids. Carotenoids are of two types. Carotene and xanthophyll.
(i) Carotene: Carotene is an unsaturated hydrocarbon compound. Its chemical symbol is C40H56O. It is of four types. Carotene a, b, c and d. It absorbs blue-violet light (449-478nm) the most. Color diversity of carotene is most interesting. Green carotene is found in avocados, red in tomatoes, reddish orange in carrots and yellow in various flowers.
(ii) Xanthophyll: Oxygenated carotene is called xanthophyll. Its chemical symbol is C40H56O2. Among the xanthophylls are lutein in green plants, lycoxanthin in tomatoes and zeaxanthin in Bhutra.

In photosynthesis, chlorophyll converts solar energy into chemical energy. It is activated by absorbing photons or quanta of sunlight and dissociates water molecules to produce H+ and OH-.

Chlorophyll is a green photosynthetic molecule. Chloroplasts are abundant in leaf mesophyll tissue. Green plants have five types of chlorophyll. Chlorophyll a, b, c, d and e. Chlorophyll-a is yellowish-green and chlorophyll-b is bluish-green. Some chlorophyll-a (P-700) absorb light at a wavelength of 700 nm, while some chlorophyll-a (P-680) absorb light at a wavelength of 680 nm. These chlorophylls participate in photosynthesis. Photoreactions occur in quantosomes of thylakoids and photoneutral reactions occur in the stroma. Modern scientists believe that light energy absorbed by chlorophyll-a is used in photosynthesis. Light energy absorbed by other pigments is passed on to chlorophyll-a. Some green sulfur bacteria like Rhodopseudomonas, Rhodospirillum, Chlorobium etc. contain bacteriochlorophyll. The chemical constituents of chlorophyll are carbon, hydrogen, oxygen, nitrogen and magnesium.
Chlorophyll-a : C55H72O5N4Mg
Chlorophyll-b : C55H70O6N4Mg
Chlorophyll-c : C35H30O5N4Mg
Chlorophyll-d : C54H70O6N4Mg

The main photosynthetic pigments are chlorophyll, carotenes and phycobilins. Chlorophyll is the main pigment of photosynthesis. Other pigments are called antenna pigments. Because they absorb light energy and give chlorophyll-a.
1. Chlorophyll: Chlorophyll is a green photosynthetic molecule. Chloroplasts are abundant in leaf mesophyll tissue. Green plants have five types of chlorophyll. Chlorophyll a, b, c, d and e. Chlorophyll-a is yellowish-green and chlorophyll-b is bluish-green. Some chlorophyll-a (P-700) absorb light at a wavelength of 700 nm, while some chlorophyll-a (P-680) absorb light at a wavelength of 680 nm. These chlorophylls participate in photosynthesis. Photoreactions occur in quantosomes of thylakoids and photoneutral reactions occur in the stroma. Modern scientists believe that light energy absorbed by chlorophyll-a is used in photosynthesis. Light energy absorbed by other pigments is passed on to chlorophyll-a. Some green sulfur bacteria like Rhodopseudomonas, Rhodospirillum, Chlorobium etc. contain bacteriochlorophyll. The chemical constituents of chlorophyll are carbon, hydrogen, oxygen, nitrogen and magnesium.
Chlorophyll-a : C55H72O5N4Mg
Chlorophyll-b : C55H70O6N4Mg
Chlorophyll-c : C35H30O5N4Mg
Chlorophyll-d : C54H70O6N4Mg
Role of Chlorophyll in Photosynthesis: In photosynthesis, chlorophyll converts solar energy into chemical energy. It is activated by absorbing photons or quanta of sunlight and dissociates water molecules to produce H+ and OH-.
2. Carotenoids: Orange carotene and yellow xanthophyll together are called carotenoids. Carotenoids are of two types. Carotene and xanthophyll.
(i) Carotene: Carotene is an unsaturated hydrocarbon compound. Its chemical symbol is C40H56O. It is of four types. Carotene a, b, c and d. It absorbs blue-violet light (449-478nm) the most. Color diversity of carotene is most interesting. Green carotene is found in avocados, red in tomatoes, reddish orange in carrots and yellow in various flowers.
(ii) Xanthophyll: Oxygenated carotene is called xanthophyll. Its chemical symbol is C40H56O2. Among the xanthophylls are lutein in green plants, lycoxanthin in tomatoes and zeaxanthin in Bhutra.
3. Phycobilins: Phycocyanin, phycoerythrin and allo-phycocyanin are collectively called phycobilins. Seven types of phycobilins are found. Cyanobacteria and red algae contain phycobilins. Phycobilins store light energy and help in photosynthesis. The red colored phycobilin is called phycoerythrin. It absorbs blue-green light. Its chemical symbol is C34H46O8N4. The blue colored phycobilin is called phycocyanin. It absorbs orange light. Its chemical symbol is C34H46O8N4.

1. Photosynthetic Plants: Photosynthesis occurs in bacteria containing photosynthetic pigments, algae, blue-green algae and all plants containing chlorophyll.
2. Photosynthesizing stems: Photosynthesis takes place in young stems, green stems with chlorophyll, leafy stems of radishes, gourds, pumpkins, ferns, etc.
3. Photosynthesizing roots: Photosynthesis takes place in the assimilating roots of golanches and aerial roots of orchids.
4. Photosynthetic Unicellular Organisms: Photosynthesis takes place in unicellular organisms like Euglena, Chlorella, Chrysamiba etc.
5. Plants incapable of photosynthesis: Photosynthesis does not occur in organisms such as parasites, dead organisms, fungi.

In 1986, Devlin proved that the process of photosynthesis takes place in the chloroplast. For this he called chloroplast as Photosynthetic apparatus. Photosynthesis occurs in the mesophyll tissue of plant leaves. Photoneutral reactions occur in the stroma of chloroplasts and photoreactions occur in quantosomes. A quantosome contains 250 chlorophylls, enzymes, electrons and pigments. Photosynthesis takes place in the green leaves of higher plants, flower petals and peduncles, green skin of flowers and fruits. Bacteria, cyanobacteria, red and brown algae carry out photosynthesis (chemosynthesis) with chromatophores. Photosynthesis occurs in the leaves and young stems of higher plants. Algae and bryophytes have chloroplasts throughout their bodies and carry out photosynthesis. Green leaves have the most chloroplasts. So green leaves are the main part of photosynthesis
is identified as Aquatic plants have a high rate of photosynthesis due to the high amount of dissolved CO2 in the water. Unicellular organisms like Euglena, Crysamoeba etc. carry out photosynthesis due to the presence of chlorophyll. The amount of CO2 in the atmosphere is 0.03% and that of water is 0.3%. Although Mucor, Yeast, Agaricus etc. are plants, they cannot carry out photosynthesis due to lack of pigments.
[ Organelles of Photosynthesis-Green Leaves, Organelles of Photosynthesis-Chloroplasts and Organelles of Photosynthesis-Thylakoids]

1. A universal energy storage compound
2. The universal molecule of energy transfer
3. The energy currency of the cell
4. The coin of the cell’s energy transfer
5. Biological coin or Energy coin.

ATP is a high-energy chemical substance. ATP is produced by the addition of ADP and Pi by the action of the ATP-ase enzyme. The process of making ATP is called phosphorylation. ATP is produced in the part of the thylakoid that faces the surface stroma. ATP is the source of chemical energy in living cells. ATP stores a lot of energy. ATP provides the energy required for various cell reactions. So ATP is called biological coin or energy coin or molecular currency. British biochemist Peter Michel proposed oxidative phosphorylation as the process of making ATP.