7 S.St. Ch.6 Life on the Earth

 7  S.St.    Ch. 6 Life on the Earth

Something To Know :

.A. Tick ( ) the correct option. 

1. Which one of the following is a threat to ecological balance? 

(a) plantation (b) wildlife protection  (c) population growth (d) growing crops 

2. Taiga  is ---

(a) a Russian name for evergreen coniferous forests. (b) an animal living in the polar region. 

( c) a softwood tree. (d) a cold desert area.  

3. For the preservation of varied plant and animal life, the government  has set up various ---

(a) zoological parks (b) industrial parks (c) national parks (d) adventure parks

4. Mosses and lichens are ---  

(a) commonly found vegetation in the polar regions. (b) trees found in tropical deciduous forests, (c) insects - eating animals. (d) animals having thick fur on their body. 

5. The temperate grasslands of North America  are called the --

(a) atacama (b) veld  (c) prairies (d) campos 

B. Fill in the blanks. 

1. The first form of life on the earth appeared in the water bodies.

2. The living zone of the planet earth is known as    biosphere. 

3. The human beings, who first appeared on the earth, were known as  Homosapiens.

4. The Taiga vegetation is also known as coniferous forest .

5. The plants prepare their own food factory of the biosphere.   

C White True or False for the following statements.  

1 In the grasslands, the number of animals is less as compared to those in the equatorial forest. 

                                                                                                             True  

2. Afforestation causes rise in the pollution level in the atmosphere.  False 

3. Tiger and lion are the endangered species in India.                        True 

4  Pampas are the temperate grasslands in Australia.                        False 

5. Insect - eating animals are most commonly found in the dense forests of the 

    equatorial region.                                                                             True

D. Answer the following questions in brief. 

 Q 1. Name the major types of vegetation of the world. 

Ans. Tropical hardwood forest, grasslands, desert and temperate softwood forests. These are

        the major types of vegetation of the world. 

Q 2. Name some common plants found in cold and hot desert regions of the world.

Ans. Plants that are found in cold regions of the world are mosses, lichens etc.

        Cactus, shrubs, and bushes are found in hot desert regions of the world. 

Q 3. What are the major components of Ecosystem? 

Ans. Eco-system: The relationship between plant kingdom, animal kingdom and human

        beings with their environment are known as Eco-system.

Q 4. Give some examples of trees having needle - shaped leaves

Ans..Pine, fir, spruce, larch etc. are some trees which have needle-shaped leaves.  

Q 5. Why do animals in the polar region have thick fur on their bodies? 

Ans. Animals in the polar region have thick fur on their bodies which protect them from extreme

        cold. 

E.Answer the following questions.  

Q 1. Why are equatorial forests known as evergreen forests?  Give a few examples of trees

       found there.  

Ans.  The equatorial forests are known as evergreen forests as  these forests remain green

       throughout the year.  These areas receive heavy  rainfall throughout the year and hence the

       forests remain green all through the year.

      Trees found in these forests are ebony,rubber,mahogany and rosewood. 

Q 2. What role do plants play in ecological balance? 

Ans.  Plants are very big sources of shelter for many living organisms and an important part of

      the food chains within an ecosystem.. Plants keep ecological balance by providing oxygen

      to living organisms and absorb carbon dioxide released by human beings. Oxygen is also

      necessary for fire which provides heat and food. 

Q 3. Distinguish between tropical and temperate grasslands. 

Ans.Tropical Grasslands : 1. The tropical grasslands are located between the equatorial

     forests and hot deserts in both the hemispheres.  

2. These grasslands receive about 100 cm rainfall.  

3. The grasses of these regions are very rough, thick and tall. 

     Temperate Grasslands : 1.The temperate grasslands are located in the temperate zone in

    the interior part of the continents.  

2. These grasslands receive about 25 to 75 cm rainfall. 
3. They sometimes receive snowfall.  

4. The grasses of these regions are soft and short.

Q 4. Differentiate between hot and cold deserts . .

Ans.  Hot Deserts : 1. The hot deserts are mostly located on the western margins of the

    continents where temperatures remain very high throughout the year.

2. The common vegetation of the hot deserts are cactus, shrubs and bushes.  

         Cold Deserts : 1.The cold deserts are mostly found around the polar regions where

    temperature remains below freezing point for the major part of the year.

2. The common vegetation of cold deserts are mosses, litchens. 

Q 5. What are the various problems related to the ecological imbalance?  What steps should we

       take to solve them?

Ans    Due to the rapid increase in population of the world, the areas under the forests are

     drastically decreasing.  Man has cleared the forests  for the sake of agriculture, habitation

     and the expansion of industries.  With the result, the ecological balance is highly disturbed all

     over the world.  This is having a far reaching effect on human beings.  In the  wildlife 

     community, a few species have already faced the danger of all extinction e.g.  tigers, lions

     etc.  The pollution level of the countries is rising to any maximum limit and therefore there is

     a rise in the global temperature which has caused even the glaciers to melt in the polar ice -

     caps. 

        In order to maintain the ecological balance --, 

1. Afforestation should be taken up on a large scale. 

2. Hunting of animals should be strictly banned. 

3. For the preservation of different animal species, the government should set up more wildlife

   sanctuaries, national parks and biosphere life  reserves.

Inside Questions :

Q 1.Give the location of tropical evergreen forest.

Ans. Tropical evergreen forests are found on both sides of the equator between 10 degree  North and 10 degree  South latitudes.

Q 2. Name some popular animals found in cold and hot desert regions of the world.

Ans.  Animals that are found in cold regions of the world are polar bear, yak, fox and penguin. Camels, horses and goats are found in the hot desert regions of the world. 

Q 3. Why is human being considered as a most important part of the biosphere?

Ans.  Human beings are the most important part of the biosphere as they derive all their basic needs from it. Human beings consume both plant food as well as animal food. It is the only form of life in the biosphere which has altered the environment according to  his own needs.

 

Short notes :

 Biosphere :  The earth is the only planet in the solar system where life exists.  The  living zone is called the biosphere. Biosphere is divided into two kingdoms namely Plants Kingdom and Animals Kingdom which live together in harmony. In this zone, living things and non-living things are also dependent on each other for their survival. 

Plants prepare their  own food and they provide food for the animals to satisfy their basic needs. Animals also provide soil nutrients which are helpful for the growth of plants.

Human beings are the most important part of the biosphere as they did at all their basic needs . It is the only form of life in the biosphere which has altered the environment according to his own needs.

Desert : A vast  area which have less distortion due to very scanty rainfall is commonly known as desert .(a) Hot Desert   (b) Cold Desert.

Eco-system: The relationship between plant kingdom, animal kingdom and human

beings with their environment are known as Eco-system.