Natural Resources
Q.1) What are Biogeochemical Cycles?
Ans) The cyclic flow of nutrients between non-living environment and living
organisms is known as Biogeochemical cycle.
Q.2) Draw and describe Carbon Cycle?
Ans) Carbon is the most significant element. The basic movement of Carbon is
from atmospheric reservoir (0.03%) to producers, to consumers and then to
decomposers. Other reservoirs of Carbon are water, fossil fuels and sedimentary rocks. Plants utilize the atmospheric CO2 in photosynthesis to produce carbohydrates. Plant food is taken by herbivores and passes to the carnivores. The respiratory activities at each level help in returning the CO2 quickly to the atmosphere. The CO2 is returned to the atmosphere by various activities such as respiration, decomposition, burning of fossil fuels and volcanic activities.
Q.3) Draw and describe Nitrogen Cycle?
Ans) Atmosphere is the reservoir for free Nitrogen (about 78%). Nitrogen in element form cannot be used by plants. First it has to be converted to nitrates, a process known as nitrogen fixation.
The three types of nitrogen fixations are:
i) Atmospheric fixation.
ii) Industrial fixations.
iii) Biological fixations.
i) Atmospheric fixations: During lightning the high temperatures and pressures created in the air convert Nitrogen into Oxides of Nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain. These nitrate and nitric ions are then used up by the plants, convert them into amino acids and then make proteins.
ii) Industrial fixations: Commercial productions of nitrogenous fertilizers.
iii) Biological fixations: Free living and symbiotic nitrogen fixing bacteria in the root nodules of leguminous plants, convert Nitrogen to form nitrites and nitrates. Animals consume the plant proteins and build their animal proteins from them. The dead bodies of plants and the dead bodies and excretions of animals undergo ammonification and nitrification by bacteria and become nitrates and nitrites.
A different type of bacteria converts nitrates back to nitrogen. This process is called denitrification.
Q.4) The percentage of CO2 in the atmosphere doubled since the industrial revolution. Why?
Ans) Human beings started burning fossil fuels on a very large scale since industrial revolution.
Q.5) Draw the Oxygen Cycle.
Q.6) What are the different states in which water is found during the water cycle?
Ans) Solid-ice, Liquid-water and Gaseous-water vapour.
Q.7) Name the two biologically important compounds which contain nitrogen and oxygen?
Ans) Proteins, nucleic acids (DNA, RNA)
Q.8) List any three human activities which would lead to an increase in the carbondioxide of air?
Ans)
1. Deforestation
2. Burning of fossils in industries
3. Use of automobiles
Q.9) What is Green House Effect?
Ans) Some green house gasses like CO2 and methane trap the sun's heat radiated from earth. This leads to an increase in the earth's temperature. This phenomenon is called Green House Effect.
Q.10) What are the results of green house effects?
Ans) Green house effect causes Global warming which in turn leads to melting of ice caps and glaciers resulting in floods.
Q.11) What causes the depletion of Ozone layer?
Ans) Chlorofluorocarbons (CFC).
Q.12) What is the result of depletion of Ozone layer?
Ans) Harmful radiations like UV radiations reach the surface of the earth and damages many forms of life. It causes skin cancer in human beings.
Q. 13) Draw a diagram of the water cycle
