Human interaction with biosphere

HUMAN INTERACTION WITH BIOSPHERE

Ecology:
Ecology was first proposed by a zoologist named H.Reiter in 1885.
It is derived from Greek words, Oikos meaning the discourse or study, thus ecology is the branch of biology which deals with the study of the relationship of living organism to each other and with their environment.
Ecologist regards these as the living part of a system called ecosystem. The different ecosystem are united to form the ‘’Biosphere.’’

Biosphere:
Biosphere I derived from German word ‘’biosphere’’ which means the region of the earth’s crust and atmosphere occupied by living organism.
It is the highest level of organization which forms the largest biological system. It is a part of earth including air, water, soil within which life occurs and biotic processes in turn alter or transform.

Man and Biosphere:
Human beings depend on natural resources such as plants and animals to meet their basic needs and wants.
These needs are obtained from plants and animals.
1. Foods:All animals require energy for the vital activities as well as physical activities. The energy is fulfilled by food.
2. Shelter:Human beings need shelter to protect themselves from various climatic factors such as extreme cold and hot temperature, wind, rain, and others disaster. For this we build a house on land. The material for the construction of house is provided by plants.
3. Cloth:We wear the clothes to protect our body from heat and cold. Plants and animals provide raw materials for manufacturing various types of cloth

Bio-geochemical cycles
The circulation of chemical nutrients like carbon, nitrogen, oxygen, phosphorus, calcium and water through the biological and physical work or biosphere is known as bio-geochemical cycle.
The four important biogeochemical cycles in nature are:
1. Water cycle
2. Oxygen cycle
3. Carbon cycle
4. Nitrogen cycle

1. Water cycle
• The most abundant compound present in all organisms is water.
• Water covers more than three fourth of earth’s surface. It is also found within the crust of earth.
• Heat of sunlight evaporates the water on the earth and forms vapour. The water vapour being lighter than air rises up and goes into atmosphere.
• The unutilized water absorbed by plants from soil is given off into atmosphere by transpiration.
• The water vapour produced due to respiration of living organism also goes into atmosphere.
• As the water vapour rises up into atmosphere, gets cooled and condensed to form tiny droplets of water and form cloud and finally falls down as rain. The rain water passes into soil and some part is absorbed in soil and utilized by plants.




2. Oxygen cycle:
• It represents about 21% of atmospheric gases. It is available in free molecular form and in combined state like carbon-dioxide, water etc.
• All living organism take oxygen from atmosphere for respiration and is converted it into carbon dioxide and water and is released in to atmosphere.
• The burning of fuels also requires oxygen from atmosphere and releases carbon dioxide and water vapour into atmosphere.
• The carbon dioxide and water vapour released in atmosphere are utilized by photosynthesis and oxygen gas formed in this process is released into atmosphere. In this way oxygen cycle is completed in nature.

3. Carbon cycle
• Carbon is the basic constituents of living organism.
• It is the most essential constituents of all the major organic compounds of the carbohydrate, fats, protein and nucleic acids.
• The atmospheric carbon dioxide serves as the source of carbon for the synthesis of organic compound in green plants. Most of the carbon dioxide enters into the living world through photosynthesis.
• The major process by which carbon dioxide is removed from atmosphere is photosynthesis by green plants.
• The green plants and their products are eaten by animals as food.
• During respiration, plants and animals give off carbon dioxide into atmosphere. Dead and decayed plants and animals also release carbon dioxide into atmosphere.
• Some dead plants and animals are changed into fossils fuel which when burnt, produce carbon dioxide.
• Volcanic eruption also releases carbon dioxide formed from decomposition of carbonate minerals.
• Carbon dioxide is also released into atmosphere when acid rain falls on carbonate rocks such as limestone. In this way the carbon cycle in nature is completed.






5. Nitrogen cycle
• Nitrogen comprises 78% of the earth’s atmosphere.
• The nitrogen forms the structural and functional component of the cell protoplasm and its organelles.
• The atmospheric nitrogen can be used only when it is converted into nitrates and nitrites by nitrogen fixation. There are 3 kinds of nitrogen fixation: atmospheric, biological and industrial fixation.
• In atmospheric fixation, nitrogen combines with oxygen during lightening and form oxides of nitrogen which dissolves in rain water, gets soaked into soil and forms nitrate.
• In biological fixation, nitrogen fixing bacteria called rhizobium present in nodules of certain leguminous plant directly fixes atmospheric nitrogen into nitrogen compounds. Some blue green algae also fix atmospheric nitrogen.
• In industrial fixation, the nitrogen gas is made to combine with hydrogen gas to form ammonia which can be oxidized to form nitrates or made to react with acid to form ammonium salt. The nitrates of ammonium salt which contain fixed nitrogen are used as fertilizers.
• The nitrates and nitrites absorbed by plants converted into plant protein.
• The purifying bacteria and fungi convert nitrogenous substance of dead plant and animals into ammonia by ammonification.
• By nitrification, nitrate salts present in soil are converted into free nitrogen gas. In this way nitrogen cycle is completed.