DAV Class 7 SST Solution Chapter 6 Life on the Earth
DAV School Books Class 7 SST Solution Chapter 6 Life on the Earth all Question Answer. DAV Class 7 6th Chapter Life on the Earth full Chapter explanation by expert teacher.
DAV School Books Class 7 SST Solution Chapter 6 Life on the Earth
1.) Which one of the following is a threat to ecological balance?
(a) plantation
(b) wildlife protection
(c) population growth
(d) growing crops
Ans – (c) population growth
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.
Ans – (c) a softwood tree.
3. For the preservation of varied plant and animal life, the government has set up various-
(a) zoological parks
(b) industrial parks
(c) a softwood tree.
(d) adventure parks
Ans – (c) a softwood tree.
4.) Mosses and lichens are-
(a) commonly found vegetation in the polar regions.
(b) trees found in tropical deciduous forests.
(c) insect-eating animals.
(d) animals having thick fur on their body.
Ans – (a) commonly found vegetation in the polar regions.
5.) The temperate grasslands of North America are called the-
(a) atacama
(b) veld
(c) prairies
(d) campos
Ans – (c) prairies
D.) Answer the following questions in brief.
1. Name the major types of vegetation of the world.
Ans – Major types of vegetation of the world are-
1.) Tropical hardwood forests, 2.) Grassland, 3.) Desert,
4.) Temperate Softwood forests
2. Name some common plants found in cold and hot desert regions of the world.
Ans – Plants found in Hot desert region are -Cactus,Shrubs,Bushes etc.
Plants found in the Cold desert region are- Mosses and Lichens.
3. What are the major components of Ecosystem?
Ans – Major components of Ecosystem are- flora world (plant kingdom), fauna world ( animal kingdom) and human beings.
4. Give some examples of trees having needle-shaped leaves.
Ans – Trees having needle shaped leaves are – Pine, Fir , Spruce, Larch etc.
5. Why do animals in the polar region have thick fur on their bodies?
Ans – Animals of the Polar region have thick fur on their bodies to protect themselves from the cold weather and the region is always covered with snow.
E.) Answer the following question-
1. Why are equatorial forests known as evergreen forests? Give a few examples of trees found there.
Ans – Equatorial forests are known as Evergreen forests. The leaves of the forests always remain green because of the heavy rainfall and high temperature throughout the year. They never shed their leaves.
For example – Ebony, Rubber, Rosewood , Mahogany etc.
2. What role do plants play in ecological balance?
Ans – Plants play a vital role to maintain the ecological balance. Plants consume carbon dioxide in the process of photosynthesis and release oxygen. Because of this the balance between CO2 and O2 could be managed and animal kingdom can breathe freely. Again they help to protect the environment from air pollution. Global warming can be checked by he process of afforestation. Moreover plants hold the soil tightly with their roots, which can help to reduce soil erosion and flood.
3. Distinguish between tropical and temperate grasslands.
Ans – Distinction between Tropical and temperate Grassland-
1.) Grasses of tropical Grasslands are tick and tall while Grasses of Temperate grasslands are Short and soft.
2.) Tropical grasslands are situated between the hot desert and equatorial forests and temperate grasslands are located in the interior parts of the continents , where the climate is temperate.
3.) Tropical Grasslands receive 100 cm rainfall ,while Temperate Grasslands receive 25-75 cm rainfall.
4.) Campos in Brazil is the example of Tropical Grass land and Pampas in South America is the example of temperate grassland.
4. Differentiate between hot and cold deserts.
Ans – Distinction between Hot and Cold desert-
1.) Temperature remains always high in the Hot desert region and temperature remains always below the freezing point in the cold desert region.
2.) Western margin of the continents are found with Hot desert and maximum parts of the polar region are called cold desert .
3.) Cactus, Shrubs are found in Hot desert area and Mosses and lichens are found in cold desert area.
4.) Sahara desert is the example of Hot desert and cold desert is found in northern part of Canada.
5. What are the various problems related to the ecological imbalance? What steps should we take to solve them?
Ans – Problems related to ecological imbalance are – pollution , global warming, deforestation, extinction of some major animals and plants, rapid growth of diseases etc.
To bring back the ecological balance in the environment Government initiatives must be taken. To protect the animal lives hunting and scattered animal husbandry should be banned. Afforestation is the another way to create balance. Again wild life sanctuary, National parks by the government should be built up to protect the animal and plant lives.
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