Q.8 Give main adverse effects of deforestation. (AKTU. - 2009 - 10)
Ans. Adverse Effect Of Deforestation: - (AKTU. - 2012 -13)
(i) Soil Erosion: -
In the absence of forests/trees, especially on slopes, the soil gets washed away with rain water.
(ii) Decrease In Rainfall: -
Forests bring rains due to high rate of transpiration and precipitation. In the absence of forests, rainfall declines considerably.
(iii) Loss Of Fertile Land: -
Less rainfall results into the loss of fertile land owing to less natural vegetational growth.
(iv) Effect On Climate: -
Deforestation causes decrease in rainfall, which in turn increases the climatic temperature.
(v) Loss Of Flora And Fauna: -
Certain species of flora and fauna are getting extinct from the face of planet, mainly due to deforestation.
(vi) Loss Of Biodiversity: -
Loss of flora and fauna has resulted into loss of biodiversity, leading to disturbances in ecological balance worldwide.
(vii) Loss Of Medicinal Plants: -
There are many species of plants which have medicinal and other advantages, like Neem (Indian Margosa) which has been used in India for centuries as insecticide, fungicide, in medicine and in biofertilizer.
(viii) Environmental Changes: -
The air we breathe, is purified by forests. So, deforestation will lead to increase in carbondioxide and other air pollutants concentration. This will lead to global warming, which is a serious effect as well as threat.
Q.9 Write short notes on:
(a) Carbon-cycle (b) Nitrogen-cycle (AKTU. - 2010 - 11)
Related Questions -
Q. Explain in brief about the nitrogen cycle with the help of cycle diagram. (AKTU. - 2012 - 13)
Ans. (a) Carbon-Cycle: - (AKTU. - 2011 - 12)
The carbon cycle begins with the use of CO2 by the green plants. During the process of photosynthesis, plants absorb carbon-dioxide and synthesize their carbohydrate food material in presence of sunlight. The organic compounds synthesized are passed from producers (green plants) to the consumers (herbivores and carnivores). During respiration, plants and animals release carbon back to the surrounding medium as carbon dioxide. CO2 is also released during the decomposition of dead bodies of plants and animals. Some part of organic matter of green plants contribute to the formation of coal deposition. By burning of coal, oil CO2 is returned to the air.
(b) Nitrogen-Cycle: -
Nitrogen is present in the atmosphere in a large amount (78%) as N2 and it is fixed either by the physical process of lightening or biologically by some bacteria and/or cyanobacteria ( blue-green algae) the nitrogen is taken up by plants and used during metabolism for the biosynthesis of amino acids, proteins, vitamins, etc. and passes through the food chain. After the death of these plants and animals, the organic nitrogen in dead tissues is decomposed by several groups of ammonifying and nitrifying bacteria which convert them into ammonia, nitrites, and nitrates, which are again used by plants. Some bacteria convert nitrates into molecular nitrogen or N2 which is released back into the atmosphere and cycle goes on.
