Life on the Earth

  • Question 53

    Distinguish between Marine and Fresh water environment.

    Marine environment : The marine environment is characterised by high concentration of salt and mineral ions. The salt concentration in the open sea is about 3.5 per cent. Salinity of the surface water and the water at various depths and latitudes varies. Salinity is least near the poles and river mouths. The sea is not a single environment. More important determinants of marine eco-systems are depth of water, distance from the shore and drainage of glaciers and rivers.

    Fresh water environment : Lakes and ponds are stagnant fresh water bodies and occur particularly in every biome. They vary in size from less than a hectare to hundreds of hectares. The relatively shallow lakes called eutrophic lakes, have a rich accumulation of organic products. The fresh water ponds are called autotrophs and have microscopic phytoplanktons.

    Streams and rivers differ in volume, temperature etc. The nature and composition of flora and fauna depend on the source of river and the land environment.

    Question 54

    Distinguish between Taiga and Tundra biomes.




    1. These are coniferous forests.

    2. Pine, fur, cedar and spruce are the prevalent trees.

    3. In some areas, trees are so dense that little light reaches the floor.

    4. This biome is good habitat for elks, deer, geese, rabbits, pumas, lynx and many insects.

    1. Tundra consists of plains characterised by snow and ice.

    2. There is poor light and extremely low temperature. Snowfall is scanty.

    3. Vegetation is so sparse that it is also called the arctic desert.

    4. This biome is virtually treeless.

    Question 55

    Distinguish between Mid-latitude Evergreen Forests and Mediterranean Forests.


    Mid-latitude Evergreen Forests

    Mediterranean Forests

    1. These forests are found in the sub-tropical belts.

    2. These forests are found in the eastern margins of the continents.

    3. In these forests, plants have broad leaves.

    4. No shrubs are found in between the trees.

    5. Oak, eucalyptus and wattle are the examples of such forests.

    1. These forests are found in the middle latitudes.

    2. These forests are found in the western margins of the continents.

    3. Trees of these forests have small leaves.

    4. Shrubs occur in between the trees.

    5. Cork, oak, olive and chestnut are the examples of Mediterranean forests.

    Question 56

    Write the difference between Tropical Deciduous Forests and Mid-latitude Deciduous Forests.


    Tropical Deciduous Forests

    Mid-latitude Deciduous Forests

    1. These forests occur in sub-tropical regions with a distinct dry season.

    2. Trees shed their leaves in the dry season.

    3. They are found in the regions of Western Europe, North-Eastern China, Japan, North-Eastern U.S.A, Southern China and New Zealand.

    1. These forests occur in the coastal regions of cool climates.

    2. Trees shed their leaves in winter season.

    3. They are found in the monsoon regions of Asia, parts of central America, Brazil and northern Australia.

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