Category: Biology Second Paper

Photosystem-I consists of three parts. Light absorption organs, reaction centers (trapping centers) and electron transport systems. It contains chlorophyll- ÔaÕ 683, carotene, xanthophyll and P-700. P-700 is a reaction dye. It absorbs ultraviolet light at a wavelength of 700 nm the most. Hence it is called P-700.

Photosystems are of two types. Photosystem-I and Photosystem-II.
1. Photosystem-I: Photosystem-I consists of three parts. Light absorption organs, reaction centers (trapping centers) and electron transport systems. It contains chlorophyll- ÔaÕ 683, carotene, xanthophyll and P-700. P-700 is a reaction dye. It absorbs ultraviolet light at a wavelength of 700 nm the most. Hence it is called P-700.
2. Photosystem-II: Photosystem-II consists of three parts. Light absorption organs, reaction centers (trapping centers) and electron transport systems. It consists of chlorophyll-ÔaÕ 673, chlorophyll-b and P-680. P-680 is a reaction dye. It absorbs red light the most at a wavelength of 680 nm. Hence it is called P-680. Photosystem-II resides mainly at the edges of the grana lamellae. Photosystem-II evolved in cyanobacteria only 3 billion years ago.

Chlorophyll molecules and electron acceptors together form a unit. This unit is called photosystem. The photosystem is located in the thylakoids and contains 400 chlorophylls. The chlorophyll and other pigments of the photosystem are collectively called the Antenna complex (AC).

(i) CO2 is used as raw material in photosynthesis.
(ii) CO2 is the source of sugar produced in the process of photosynthesis.
(iii) Carbon particles of carbon dioxide become attached to cell compounds.

CO2 is the main raw material for making sugar. The amount of CO2 in the atmosphere is 0.03%. 1% of atmospheric CO2 is used for photosynthesis. Chemical reactions of water and CO2 take place in chloroplasts. Photosynthesis requires 6 molecules of CO2 to produce one molecule of glucose.

(i) Converts solar energy into chemical energy.
(ii) serves as the site of photosynthesis.
(iii) Chlorophyll absorbs photon particles of light.

Chlorophyll is the main pigment of photosynthesis. The chloroplasts contain chlorophyll inside the quantosomes. Chlorophyll pigments are chlorophyll-a (green), chlorophyll-b (blue-green), chlorophyll-c, chlorophyll-d, chlorophyll-e, carotene (orange), xanthophyll (yellow),
Phycocyanin (blue), phycoerythrin (red), bacteriochlorophyll, chlorobium chlorophyll etc. Chlorophyll-a is of two types. Chlorophyll- ÔaÕ 673 and chlorophyll- ÔaÕ 683. The chemical components of chlorophyll are carbon, hydrogen, oxygen, nitrogen and magnesium. Bacterial chlorophyll is called bacteriochlorophyll (C55H74O6N4Mg). Like- Rhodopseudomonas, Rhodospirillum, Chlorobium etc.

(i) Solar energy helps convert ADP to ATP.
(ii) Light regulates the opening and closing of stomata.
(iii) provides the energy required for the photosynthesis process.
(iv) It excites electrons in chlorophyll. That is, it activates chlorophyll.
(v) The rate of photosynthesis can be maximized by increasing the amount of light from 100 to 3,000 footcandles.

In the hot core of the Sun, hydrogen atoms are converted into helium atoms. 4 hydrogen atoms become one helium atom. The energy emitted during the transformation is called a photon particle. Photon particles arrive at Earth as electromagnetic waves. Cosmic-rays (0.01-0.1), X-rays (0.1-10) and gamma rays (10-390) have shorter wavelengths and infrared (700-1,00,000) and radiomagnetic The wavelength of the ray (1,00,000-α) is much longer.
Light that is visible (visible) is called white light. The wavelength of visible light is 390-760 nanometers. Only visible light is used in the process of photosynthesis. Visible light consists of 7 colors of light. These lights are called light spectrum. The wavelength of the spectrum is violet 390-430 nm, blue 430-470 nm, sky 470-500 nm, green 500-
8-10 photons are needed to oxidize one molecule of CO2. This number of photons is called quanta. 50-60 photon particles are used to make one molecule of glucose. The amount of light incident on the material that is absorbed is called the absorption spectrum. 83% of incident sunlight is absorbed by green leaves, 12% is reflected in the atmosphere and 5% is lost underground. 0.5-3.5% of the light energy absorbed by green leaves is absorbed by chlorophyll and other pigments. Violet, blue, orange and red light are mostly used in photosynthesis. The rate of photosynthesis is higher in red and blue light. However, as a single light, red light has the highest rate of photosynthesis.
Scientist Robert Emerson applied light to the chloroplasts of Chlorella algae and observed that the rate of photosynthesis decreases with more light at a wavelength of 680 Hz. He called red drop when the rate of photosynthesis decreases in the red part of the light spectrum. Robert Emerson and his colleagues combined light with wavelengths shorter than 680 nm with wavelengths longer than 680 nm.
Apply photosynthesis. They found that the combined photosynthetic rate was higher than the combined photosynthetic rates of the two types of light combined. They called it the Emerson enhancement effect.

(i) Oxygen produced as a by-product of photosynthesis comes from water.
(ii) Water is used as the main raw material in photosynthesis.
(iii) Hydrogen is needed during the oxidation of carbon dioxide in the dark phase of photosynthesis. Hydrogen is produced from water.
(iv) It donates electrons to chlorophyll molecules.