• What do you mean by 'Biosphere Cycle' ?
Ans : Biosphere means sphere of life. The idea of Biosphere was suggested by Austrian geologist Edward Suess nearly a century ago. At that time it was not a so important concept. Today, however, the biosphere has become the most important problem faced by man. The basic function of biosphere is that it supports life. It is estimated that biosphere contains more than three hundred and fifty thousand species of plants and eleven million animal species including man. The biosphere supplies the essential requirements for Society and Environment all those species such as plants, animal and human beings namely light, heat, water, food and living space etc.
Biosphere cycle : Maintenance of the biosphere is possible through constant recycling of materials between the biotic (living) and abiotic (nonliving) components .These cycles are as given below;
(i) Hydrological cycle : The path of water through environment is hydrological cycle
(ii) Carbon Cycle: Carbon serves two purposes in the environment ( I ) It is structural component of organic molecules and (2) the energy holding chemicals bonds it forms for energy storage.
(iii) Nitrogen cycle: Organisms cannot exist without amino acids, peptides, nucleic acids and proteins all of which are organic molecules containing nitrogen.
(iv) The Phosphorus cycle : Minerals become available to organisms after they are released fro rocks. Phosphorus cycle is one of the mineral cycle begins when phosphorus compounds are leached from rocks and minerals over long periods of time. I
(v) The Sulphur Cycle.-. Sulphur plays a vital role in organisms, especially as a minor but essential component of proteins. Sulphur compounds are in portant determinants of the acidity of rainfall, surface water and soil.
(vi) Oxygen Cycle: Oxygen is the main source of respiratory gas for all terrestrial organisms.
• Explain in brief the carbon dioxide cycle.
Ans : Carbon is essential to life, carbon is the basic building block of the carbo-hydrates. Fats, proteins, DNA (Deoxyribo Nucleric Acid) and other organic compounds necessary for life.
The carbon-cycle is based on carbon-dioxide gas, which makes up0.036% of the volume of the troposphere and is also dissolved in water. Carbon dioxide is a basic components of nature's thermostat. If carbon cycle removes too much CO2 from the atmosphere, the atmosphere will cool : if the cycle generates too much, the atmosphere, the atmosphere will get warmer . Thus, even slight changes in the carbon cycle can affect climate and ultimately the types of life that can exist in various parts of the planet.
Terrestrial producers remove CO2 from the atmosphere and aquatic producers remove it from the water. Then they use photosynthesis to convert, CO2 into complex carbohydrates such as glucose.
The cells in oxygen producers, consumers and decomposers then carry pit aerobic respiration. This breaks down glucose and other complex organic compounds and converts the carbon back to CO2 in the atmosphere or water for reuse by producers. This connection between photosynthesis in producers and aerobic respiration in producers, consumers, and decomposers circulates carbon in the biosphere and is a major part of the global carbon cycle. So the process of photosynthesis, respiration, decomposition and combustion (burning) or fossil fuels mainly maintains carbon cycle.
7.6 Explain in brief the main causes of eco-imbalance .
Ans : Causes of Eco-Imbalance : The Reasons which cause ecological imbalance are given below. : If beyond 30% of forest land area is resprted to tree-felling then eco-balance is disturbed about 95% of the land in the arid and semi-arid regions of the world are in the process of desertification.
Delineation means changing land into desert area.
1. Deforestation brings about erosion and soil movement. A large number to trees along the roadsides are falling down due to road construction. Improper road construction results in soil erosion that may lead to uprooting of large trees and degeneration of lower counts. This way it leads to serious ecological imbalances affecting adversely run-off factors, temperature gradient, and surface radiation.
2. Aerobic process accumulation enhancing need of BOD, COD and DO emanating from sewage and other wastes.
3. Industrial effluents and Agricultural discharges,
4. Automobiles . More than 40 lakhs surface transport moves on the roads of Delhi only.
5. lndustrial chimney . Thermal Power Stations, emission of flyash and dust from stone crushers.
6. Population and Gulf-war : A brief review of Gulf-war is described in a tabulated shape.
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