Maharashtra Board Class 6 Geography Solution Chapter 6 – Importance of Oceans
Balbharati Maharashtra Board Class 6 Geography Solution Chapter 6: Importance of Oceans. Marathi or English Medium Students of Class 6 get here Importance of Oceans full Exercise Solution.
|
Std |
Maharashtra Class 6 |
| Subject |
Geography Solution |
|
Chapter |
Importance of Oceans |
(A) Find the odd man out:
(1) Shell, fish, Crab, ship
(2) Arabian Sea, Mediterranean Sea, Dead Sea, Caspian Sea
(3) Srilanka, India, Norway, Peru
(4) Southern Ocean, Indian Ocean, Pacific Ocean, Bay of Bengal
(5) Natural gas, Salt, Gold, Manganese
(B) Write the answer
(1) Which items does man get from the sea?
Ans: – We get fish, from the sea. Though food is the major purpose of this activity, marine animals are also used in fertilizers. In India, people mainly consumes Prowens (Kolambia), Clams (tisre), Crabs, Selfish (Surmai), Mackerel (bangda), Pomfret (Paplet), Indian shark(mori), Indian Salmon (ravas)etc. Several food items are produced from these fishes. We also get some minerals like gold, minerals, natural gas from the sea. We get precious items like pearls, corals or ornamental items like shells, as also medicinal plants from the sea.
(2) Why is it economic to carry out transport by waterways?
Ans: – Oceans have provided us the most economic option for transportation. Ocean currents are quite important in water transport. As far as possible water transport is carried out along ocean currents. They accelerate the speed of ships and also save fuel to a considerable extent. That’s why it is important to carry out transport by waterways.
(3) Why is there a difference in the climates of regions close to the oceans and regions far way from the oceans?
Ans: – There is different in the maximum and the minimum temperature in the areas which are close and far away from the oceans. This difference is less in the coastal areas while it is more in the regions far away from the sea (continantatity)
The main caused for this is the mixing of vapour released through evaporation of water from these water bodies into air. This vapour in the air absorbs and stores the heat released from the land.
Hence, the temperature in coastal areas remains equable.
(4) Which continents are located along the coast of the Pacific Ocean?
Ans: – The continents: Asia, Australia and South America are located along the coast of the Pacific Ocean.
More Extra Questions from this Chapter:
1.) What is hydrosphere ?
A:- All the water bodies of the earth , oceans rivers ponds lakes are called hydrosphere.
2.) __________ percentage of all water on earth is sea water.
A:- 97.7
3.) . The average salinity of oceanic waters is __________.
A:- 35 %o.
4.) Which sea water is the max salinity in the world and what is its salinity?
A:- The most salty sea in the world is the dead sea. Its salinity is amount 332 %o.
5.) What is planetary winds ?
A:- Different types of high pressure and low pressure belts are formed due to temperature difference. For these belts the air flows from the action to another place called planetary wind.
6.) In which city is sea water being converted into drinking water through filters ?
A:- The sea water of the city of Dubai in the United Arab Emirates is being converted into drinking water through filters.
7.) The wood of _____________ trees is light and oily.
A:- Mangrove
8.) Which country’s coastline is best for Oceanic Transport ?
A:- Spain Norway japan coastline are good for Oceanic Transport .
9.) _______ of the surface of the earth is occupied by water.
A:- . 70.8%
- ) __________ is one of the ancient occupations of human beings.
A:- Fishing
11.) Which type of forest tree is grow predominant in coastal areas ?
A:- In coastal areas mangrove forests with tivari and sundary grow well.
12.) Match the following
|
Ocean |
Area |
|
Atlantic |
73,426,163 |
| Pacific |
86,557,402 |
|
Southern |
13,224,479 |
| Arctic |
20,327,000 |
|
Indian |
166,240,977 |
More extra Questions
Multiple choice questions: (marks:1)
1.) Out of the total global waters,ocean contains:
A.) 97.7%
B.) 97.8%
C.) 98.7%
Ans: 97.7%.
2.) Assertion (A): The Earth is known as the water planet.
Reason(R) : The proportion of water is greater than the proportion of land on Earth.
A.) Both A and R are true and R is the correct explanation of A.
B.) Both A and R are true but R is not the correct explanation of A.
C.) A is true but R is false.
D.) R is true but A is false.
Ans: Both A and R are true and R is the correct explanation of A.
3.) The average salinity of oceanic water is:
A.) 30‰
B.) 35‰
C.) 37‰
Ans: 35‰.
Answer the following questions: (marks:1)
1.) What is hydrosphere?
Ans: Hydrosphere is all the water bodies that exist on the Earth. This includes all the oceans,seas,rivers and their tributaries,lakes, reservoirs and also groundwater.
2.) What is called the southern ocean?
Ans: The water body that extends from 60°S parallel to the coast of the Antarctic continent is named as the southern ocean.
3.) Which is known to have the maximum salinity?
Ans: The dead sea has the maximum salinity. It’s salinity is 332‰.
Answer the following questions:(marks:2/ 3)
1.) What are planetary winds?
Ans: the planetary winds are the winds that blow from high pressure belts towards low pressure belts occupying vast areas of the planet. They blow regularly. These include the easterlies, westerlies and polar winds.
2.) What are the resources we get from the oceans?
Ans: One can obtain salt, fish, shells and other products from the ocean. Besides these, we get minerals like iron, lead, cobalt, sodium, manganese, chromium, zinc, etc. from the ocean floor. We also get mineral oil and natural gas.
3.) Write down the areas occupied by oceans?
Ans: We know that Earth is called the water planet because the proportion of water is greater than the proportion of land on Earth. The areas occupied by the ocean of the Earth is:
Pacific-166,240,977
Atlantic -86,557,402
Indian- 73,426,163
Southern- 20,327,000 Arctic -13,224,479.
Answer the following questions:(marks:5)
1.) How oceans control the global temperature – discuss.
Ans: Earth is a diverse planet in many ways. Thus, there are differences in the temperature of different places on the earth. Similarly, there is difference in the maximum and minimum temperatures. This difference is less in the coastal regions while it is more in the regions far away from the sea. This means that in regions close to the oceans, seas or large reservoirs, there is not much of a difference in the temperature throughout the day. The main reason for this is:
- The mixing of vapour released through evaporation of water from these water bodies into air. This vapour in the air absorbs and stores the heat released from the land.
Hence, the temperature in coastal areas remains equal.
- The equatorial region receives near perpendicular sunrays. As a result, these areas get more heat whereas the polar regions receive highly slant rays. This differential heating creates an imbalance in the temperature of air in different parts. This leads to formation of belts of high and low pressure on the earth. Winds blow due to pressure differences in these belts. These winds are called Planetary Winds. These winds move the oceanic water in the form of currents. These currents are warm currents or cold currents. Warm currents move towards cold regions and cold currents move towards warm regions. This means ocean currents move from the equatorial region to polar regions and from polar regions to the equatorial region. This leads to the redistribution of heat on the earth. The cold currents moving towards the equatorial region make the temperature of coastal areas in that zone milder whereas the warm currents coming in the colder regions cause temperatures in coastal areas to rise.
The oceans act as the controller of global temperature in the two ways mentioned above. The oceans have a vast expanse, therefore huge amounts of vapour get created. This process goes on continuously. From this vapour, the earth gets rainfall. Oceans are the source of rain. The rainwater flows through rivers and streams and finally flows back into oceans. This makes it clear that the beginning and end of the water cycle takes place in the oceans.
2.) What are the issues related to oceans?
Or,
What are the causes of pollution of oceans?
Ans: About 70.8% of the surface of the earth is occupied by water and out of the total global waters the ocean contains 97.7%. In order to fulfil the requirements, man undertakes many activities. These lead to the production of huge amounts of different types of waste. These waste materials cause pollution. Pollution of oceanic waters is a major and serious issue that has developed in recent times. The causes are:
- Oil spills: oil spillage to the ocean water from the ships is causing water pollution.
- Releasing products into the water: The coastal cities released their waste products into the sea causing water pollution.
- Sewage system: Due to industrialization,sewage released by the industries and cities to the oceans caused water pollution.
- Material thrown out from ships: waste and garbage products of ships such as, plastic and paper material, food waste, cleaning material waste etc. Thrown out into the water caused water pollution.
- Disaster caused by water mines: Accidental mine accidents such as,leak of poisonous substances caused water pollution and extinction of species. F. Other causes:
- Exploitative fishing,
- Cutting of mangrove forests in coastal regions and
- Excavation carried out in the sea.
All the points mentioned above lead to large scale pollution of oceanic waters. Some coastal regions are proving to be death traps for aquatic animals. As a result, many aquatic animals are under the threat of being extinct e.g. the blue whale, some types of sea turtles, dolphins, etc.
3.) What are the factors that contribute to the salinity of water?
Ans: Water from the oceans has a greater amount of salt. That is why it tastes salty. The factors behind this:
- There is abundant aquatic life in the oceans. From the microscopic planktons to huge whales, different types of living things are found in the oceans. Once they die, their remains accumulate in oceans.
- All rivers flowing from mountains or hilly areas finally meet the oceans. Sediments from eroded lands, trees and bushes flowing with the water, dead remains, etc. enter the ocean with this river water.
In both the above processes, the dead remains decompose, releasing various minerals and salts in the ocean water.
- Volcanic eruptions occur on land. Similar volcanic eruptions take place in the ocean as well. During volcanic eruptions different minerals, ashes, salts and gases are added to the water. This increases the level of salts and minerals in ocean water.
- Due to the continuous evaporation of oceanic waters, the proportion of salts increases. All these things make the ocean water salty.
The salinity of ocean water is different at different places. Salinity is expressed in terms of mils (particles per thousand). The average salinity of oceanic waters is 35‰ The Dead Sea is known to have the maximum salinity. Its salinity is 332 ‰.
