photosynthesis

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Mohl's half leaf experiment

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Experiment to demonstrate Moll’s half-leaf experiment for showing that CO 2 , light, chlorophyll and water are necessary requirements for photosynthesis: Requirements: A potted plant, caustic potash, wide- mouthed bottle, iodine, split cork, water Method: 1. De-starch a potted plant by putting it in complete darkness for two days. 2. Fill partly a wide-mouthed bottle with strong solution of caustic potash and fit a split cork on its mouth. 3. Insert about half of the portion of a leaf of the de-starched plant into the bottle through the split cork (Fig. 36). 4. Place the whole apparatus in light after applying grease on the upper portion of split cork, and test the leaf for stach after about 10 hours. Observations: Portions of the leaf inside the bottle as well as in between the split cork show negative test for starch indicating the absence of photosynthesis while the portions outside the split cork show positive test for starch indicating the presence of process of photosynthesis in ...
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EUTROPHICATION

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When water bodies such as lakes, estuaries and slow moving streams receive excess nutrients ,it results in excessive plant (algal) growth . This process is called eutrophication. This excessive growth of plants such as  Water hyacinth and algae reduces the dissolved oxygen (BOD- biological oxygen demand) in water. The water body then becomes incapable of supporting fishes and  other forms of aquatic life. Excessive growth of algae in such water bodies is described as algal bloom. Nitrates and phosphates are the two main substances(nutrients) that causes such condition, which is a direct result of pollution. These nutrients come from a variety of sources,such as fertilizers applied to agricultural fields and golf courses, excessive use if detergents, erosion of soil containing nutrients,untreated sewage and discharges from sewage treatment plants. EUTROPHICATION not only leads to reduced oxygen but also produce foul odour and slow death of water body. Thus, biodiver...
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NATURAL RESOURCES

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Anything obtained from the natural environment to meet our needs or is important for our survival is a natural resource. Thus, air,water,and soil are necessary for survival; whereas metals,other minerals (including fuels),and forests serve to meet our needs. These are all examples of natural resources. Technological advancements has enabled us to keep adding to  this of resources to support our changing lifestyles. These can be called as human made resources. Plastics, optic fibres and synthetic fibres are examples of such resources. AIR Air is a mixture of gases constituting mainly of nitrogen and oxygen and to a smaller extent carbon dioxide,noble gases,a small percentage of water vapour and traces of other gases. Their respective composition are: Nitrogen: 78.084% Oxygen: 20.947% Carbon dioxide: 0.033% Argon: 0.934%  Air is very essential for our survival. When we say this, we often refer to oxygen but even other gases are also of equal importance. About 75% of the earth's ...
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