Life on the Earth

  • Question 1

    Describe biosphere.

    The biosphere consists of all the living components of the earth–plants, animals, microorganisms and their interactions with the surrounding environment. Thus it includes whole of the region of the earth- that is inhabited by the living organisms-lithosphere and or the hydrosphere as well as atmosphere.
    Question 2

    Define ecology.  

    The term ecology is derived from the Greek word ‘oikos’ meaning ‘house’, combined with the word ‘logy’ meaning the ‘science of’ or ‘the study of ’. Literally, ecology is the study of the earth as a ‘household’, of plants, human beings, animals and micro-organisms. 
    Question 3

    Describe the oxygen cycle. 


    The Oxygen Cycle:

    i. Oxygen is the main by-product of photosynthesis.

    ii. It is involved in the oxidation of carbohydrates with the release of energy, carbon dioxide and water.

    iii. The cycling of oxygen is a highly complex process. Oxygen occurs in a number of chemical forms and combinations.

    iv. It combines with nitrogen to form nitrates and with many other minerals and elements to form various oxides such as the iron oxide, aluminium oxide and others.

    v. Much of oxygen is produced from the decomposition of water molecules by sunlight.

    Question 4

    Describe the types of biogeochemical cycles. 


    There are two types of biogeochemical cycles:

    i. The gaseous - In the gaseous cycle, the main reservoir of nutrients is the atmosphere and the ocean.

    ii. The sedimentary cycle - In the sedimentary cycle, the main reservoir is the soil and the sedimentary and other rocks of the earth’s crust.

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