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SULFUR CYCLE Sulfur is one of the most abundant elements on the earth. Sulfur is a yellow, brittle, tasteless, odourless non-metal. Sulfur is present in all kinds of Proteins. Plants directly absorb Sulfur-containing Amino acids such as Methionine, Cystine and Cysteine. Sulfur is released into the atmosphere by the (i)  Burning of Fossil fuels; (ii)  Volcanic activities and (iii)  Decomposition of Organic molecules. On land, Sulphur is stored in underground rocks and minerals. It is released by Precipitation, Weathering of rocks and Geothermal vents. Photosynthetic and Chemosynthetic microorganisms contribute the environmental Sulfur cycle. STEPS INVOLVED IN SULFUR CYCLE The sulfur cycle describes the movement of Sulfur through the atmosphere, mineral forms, and through living things. Microbial transformations of Sulfur are even more complex than those of Nitrogen because (i)  Large number of Oxidation states of Sulfur and (ii) Several transformations of Sulfur also occur spontaneo

PHOSPHOROUS CYCLE Phosphorus is an important element for all living organisms. Phosphorus forms a significant part of the structural framework of DNA and RNA. Phosphorus is also an important component of ATP and Lipids (fats and oils). Humans contain 80 % of Phosphorus in teeth and bones. Phosphorus is an essential nutrient for animals and plants. Insufficient phosphorus in the soil can result in a decreased crop yield. In Phosphorous cycle, the Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms. The Phosphorous cycle is a slow process when compare to other Biogeochemical cycles. STEPS INVOLVED IN PHOSPHOROUS CYCLE Phosphorous cycle Phosphorous cycle has four steps. They are Weathering Absorption by Plants Absorption by Animals Return of Phosphorous back to Ecosystem through Decomposition 1) Weathering Phosphorous is most commonly found in rocks. The phosphorus cycle starts in the Earth’s crust.  Weat

CARBON CYCLE Carbon is called as the “ chemical building block of life ” because living organisms are made up of it. Carbon cycle is the process where Carbon compounds   are interchanged among the Biosphere, Geosphere, Pedosphere, Hydrosphere, and Atmosphere of the earth. STEPS INVOLVED IN CARBON CYCLE Carbon cycle In general, Carbon cycle has four steps. They are Photosynthesis Decomposition Respiration Combustion 1) Photosynthesis Carbon present in the atmosphere is absorbed by plants for Photosynthesis. Plants pull in Carbon-di-oxide out of the air through photosynthesis. Even though, Carbon-di-oxide makes up less than 1 % of the atmosphere, it plays a major role for living things. With CO 2  and H 2 O in the atmosphere, photosynthesis produces sugars like Glucose. This is the plant material that plants synthesize on its own.   2) Decomposition Plants are then consumed by animals, and carbon gets bioaccumulated into their bod

NITROGEN CYCLE Nitrogen is the most abundant element in the atmosphere. Although, 78 % volume of the atmosphere is Nitrogen gas. Nitrogen is essential to life because it is a key component of proteins and nucleic acids. The Nitrogen cycle refers to the cycle of nitrogen atoms through the living and non-living systems of Earth. STEPS INVOLVED IN NITROGEN CYCLE Nitrogen cycle In general, Nitrogen cycle has Five steps. They are 1)     Nitrogen fixation 2)     Nitrification 3)     Assimilation 4)     Ammonification 5)     Denitrification 1) Nitrogen fixation Nitrogen fixation refers to the conversion of atmospheric Nitrogen gas (N 2 ) into Ammonia (NH 4 ) or related nitrogenous compounds, a form usable by plants and other organisms. In Nitrogen fixation, the N 2 is split up into free N 2 atoms by breaking the triple bond (N≡N) with the help of an enzyme Nitrogenase. Nitrogen fixation can takes place by two methods. They are

PHOTOSYNTHESIS REACTIONS Photosynthesis takes place in two stages. In the First stage, called the Light reactions, the light energy is used to convert ADP and Phosphates to ATP. In addition, in the predominant form of the light-dependent reactions, the electron carrier NADP + is reduced to NADPH. The coenzyme NADPH, like NADH, is an energy- rich carrier of electrons. In the Second stage, the light-independent (Dark) reactions, these electrons are used along with energy from ATP to reduce CO 2 to Carbohydrate sugar. LIGHT REACTION (or) LIGHT DEPENDENT REACTION (or) PHOTOPHOSPHORYLATION Photophosphorylation is one of the three ways ATP is formed, and it occurs only in photosynthetic cells. In this mechanism, Light energy is absorbed by Chlorophyll molecules in the photosynthetic cell, exciting some of the molecules electrons. The Chlorophyll is located in the membranous Thylakoids of Chloroplasts in Algae and Green plants. In Cyanobacteria, Thylakoids are found in the photosynthetic

  Difference between Plant, Algal and Bacterial Photosynthesis Features Plant & Algal Photosynthesis Bacterial Photosynthesis Organisms Plant, Algae & Cyanobacteria Purple bacteria & Green bacteria Oxygen production Oxygenic and Aerobic Anoxygenic and Anaerobic Photosynthetic pigments Chlorophylls, Carotenoids and Phycobilins (400 to 600 nm) Bacteriochlorophyll, Bacterioviridin and Open chain aliphatic Carotenoids (above 700 nm) Types of Chlorophyll Chlorophyll – a and Chlorophyll – c (only in certain Marine algae) Bacteriochlorophyll – a (Green bacteria) & Bacteriochlorophyll – a or b (Purple bacteria) Site of Photosynthesis Chloroplast with Thylakoids (Plants & Algae) and Thylakoids (Cyanobacteria) Chromosomes (Green bacteria) and Chromatophores (Purple bacteria)