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Std: 6th, , Sub: Geography, 6. IMPORTANCE OF OCEANS, SUMMATIVE EVALUATION, 1. QUESTIONS AND ANSWER, , Q. 1. Place a tick mark against the correct option:, (1) How many sq. km. is the area of the Pacific Ocean?, 166, 240, 977 ✔, 73,426, 163, 20.327,000, (2) Which of the following ocean's area is 13, 224, 479 sq. km?, Atlantic, Southern, Arctic✔, (3) Which of the following is the cheapest mode of transport?, Airways, Waterways ✔, Roadways, Q. 2. Find out the odd man out: (Note: Use an Atlas), (1) Shell, Fish, Crab. Ship., Ans. Ship. (Ship is manmade. All other things are naturally found in oceans.), (2) Arabian Sea, Mediterranean Sea. Dead Sea, Caspian Sea., Ans. Dead Sea. (Dead Sea is comparatively smaller. All other given seas are comparatively larger.), (3) Sri Lanka, India. Norway, Peru., Ans. Peru. (Peru is to the south of the equator. All other given nations are to the north of the, equator.), (4) Southern Ocean, Indian Ocean, Pacific Ocean. Bay of Bengal.., Ans. Bay of Bengal. (Bay of Bengal is a bay. All others are oceans.), (5) Natural gas. Salt, Gold, Manganese., Ans. Natural Gas. (Natural gas is a gas. All others are minerals.)
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Q. 3. Name the following:, (1) Oceans in the world:, Ans. (1) Pacific Ocean (2) Atlantic Ocean (3) Indian Ocean (4) Southern Ocean. (5) Arctic Ocean., (2) Countries/islands where the life of people largely depends on the sea :, Ans. (1) Seychelles (2) Mauritius (3) Maldives, etc., (3) Countries that have gained importance in water transport:, Ans. (1) Spain (2) Norway (3) Japan, etc., 4) The main marine animals consumed in India:, Ans. (1) Prawns (Kolambi) (2) Clams (Tisre) (3) Crabs. (4) Seerfish (Surmal) (5) Mackerel (Bangda) (6), Pomfret (Paplet) (7) Indian shark (Morli) (d) Indian salmon (Ravas), etc., (5) Minerals obtained from oceans:, Ans. (1) Iron (2) Lead (3) Cobalt (4) Sodium (5) Manganese (6) Chromium (7) Zinc, etc., (6) Means of water transport:, Ans. (1) Ships (2) Trawlers (3) Boats, etc., (7) Main constituents of the hydrosphere :, Ans. (1) Oceans (2) Seas (3) Rivers their tributaries (4) Lakes (5) Reservoirs and (6) Groundwater., Q. 4. Answer the following questions in one sentence each :, (1) How much per cent of the total global water is contained in oceans?, Ans. 97.7 per cent of the total global water is contained in oceans., (2) Which sea is known to have the maximum salinity?, Ans. The Dead Sea is known to have the maximum salinity., (3) Where does the water flowing through the rivers go in the end?, Ans. The water flowing through the rivers goes in seas/oceans in the end., (4) For Which Purpose are marine animals used?, Ans. Marine animals are used for preparing Various food items, producing fertilizers, pharmaceuticals,, etc. and for research., (5) What are the planetary winds?, Ans. Winds that blow due to pressure difference in the pressure belts are called the planetary winds., (6) Which ocean currents move from the equatorial region to the polar regions?
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Ans. Warm ocean currents move from the equatorial region to the polar regions., 7) Which ocean currents move from the polar regions to the equatorial region?, Ans. Cold ocean currents move from the polar regions to the equatorial region., (8) What is the source of rains?, Ans. Oceans is the source of rains., (9) How much per cent of the surface of the earth is occupied by water?, Ans. About 70.8 per cent of the surface of the earth is occupied by water., (10) Which continents are located along the coast of the Pacific Ocean?, Ans. The continents of North America, South America, Asia and Australia are located along the coast, of the Pacific Ocean., (11) Are there volcanic eruptions in the seas?, Ans. There are volcanic eruptions in the seas., Q. 5. Answer the following questions in brief:, (1) Which items does man get from the oceans?, Ans. Man gets the following items from the oceans: (1) Minerals like iron, lead, cobalt, sodium,, manganese, chromium, zinc, etc. (2) Precious items like pearls and corals and ornamental items like, shells (3) Mineral oil and natural gas. (4) Food items like prawns, clams, crabs, seerfish, mackerel., pomfret. Indian shark. Indian salmon, etc. and medical plants., (2) Why is it economic to carry out transport by waterways?, Ans. (1) By waterways, bulky materials like coal, crude oil, raw materials, metallic materials, food, grains, etc. can be transported with ease. (2) Water transport carried out along ocean currents,, accelerates the speed of ships and also saves fuel to a considerable extent. Therefore, it is economic, to carry out transport by waterways., (3) Why is there a difference in the climates of regions close to the oceans and regions far away from, the oceans?, Ans. (1) In the regions close to the oceans, because of the heating of sea water, water vapour gets, mixed in the air. (2) This water vapour holds the heat in the air and the air remains humid. (3) Humid, air leads to less amount of difference in the day and night temperature (range of temperature)., Therefore, regions close to the oceans have an equal climate. (4) In the regions far away from the, oceans, the amount of water vapour is extremely less. As its effect, the air remains dry. (5) Dry air, leads to a sharp difference in the day and night temperature (range of temperature). Therefore,, regions far away from the oceans have an extreme climate. In this way, there is a difference in the, climates of regions close to the oceans and regions far away from the oceans., 4) What are the causes of pollution of oceanic water?
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Ans. The following are the causes pollution of oceanic water: (1) Oil spills. (2) Releasing the waste, produced in the coastal cities into the seas. (3) Materials thrown out from ships. (4) Exploitative, fishing. (5) Cutting of mangrove forests in coastal areas. (6) Disasters caused by the water mines. (7), Sewage released by industries and cities. (8) Excavations carried out in the seas., (5) Explain the causes of increase in the level of salts and minerals in ocean water., Ans. The following are the causes of increase in the level of salts and minerals in ocean water: (1), Remains of aquatic life, sediments from eroded lands, trees and bushes flowing with the river water,, dead remains, etc. enter into ocean. The dead remains decompose releasing various minerals and, salts in the ocean water. (2) Volcanic eruptions take place in oceans. During volcanic eruptions,, different minerals, ashes, salts and gases are added to the ocean water. (3) Due to continuous, evaporation of ocean water, the proportion of salt automatically increases., (6) Write in brief about pressure belts., Ans. (1) The equatorial region receives perpendicular sunrays. As a result, this region gets more heat., On the other hand, polar regions receive extremely slanted sunrays. As a result, these regions get less, heat. (2) This differential heating creates imbalance in the temperature of air in different parts. This in, turn leads to formation of belts of high and low pressure on the earth. (3) Winds blow due to pressure, differences in these belts. These winds are called Planetary Winds., (7) Write in brief about the water cycle., Ans, (1) The oceans have vast expanse. Therefore, huge amount of vapour is created. (2) From this, vapour, the earth gets rainfall. Thus, oceans are the source of rains. (3) The rainwater flows through, streams and rivers and finally flows back into the oceans. (4) It means the beginning and end of the, water cycle takes place in the oceans. (5) The water cycle indicates that the movement of water, between earth's surface and earth's atmosphere is continuous in nature.
