Class 8.Geography:5.Ocean Currents/ Questions and answers Maharashtra Board

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Class 8 Geography

Chapter 5 Ocean Currents

Q 1. Choose the correct option :

 (a) In which ocean does the Labrador

current flow?

 (i) Pacific

 (ii) South Atlantic

(iii) North Atlantic

 (iv) Indian 

Ans: (iii) North Atlantic

 (b) Which current out of the following

flows in the Indian Ocean?

(i) East Australian Current

 (ii) Peru current

 (iii) South Polar current

 (iv) Somali current 

Ans: (iv) Somali current

 (c) Which factor out of the following does

not affect the region along the coast?

 (i) Precipitation

 (ii) Temperature

 (iii) Land breezes

 (iv) Salinity 

Ans: (iii) Land breezes

 (d) Which of the following occurs in the

area where the cold and warm

currents meet?

 (i) High temperature

 (ii) Snow

 (iii) Low temperature

 (iv) Thick fog

Ans: (iv) Thick fog

 (e) Which of these following currents

flows from the northern polar

region upto Antarctica?

 (i) Warm ocean currents

 (ii) Surface ocean currents

 (iii) Cold ocean currents

 (iv) Deep ocean currents

Ans: (iv) Deep ocean currents

Q 2. Examine the given statements and correct the wrong ones.

 (a) Ocean currents give specific direction

and velocity to the water

Ans: Correct

 (b) The deep ocean currents flow with high velocity 

Ans: Correct

 (c) Generally, surface ocean currents are

formed in the equatorial regions. 

Ans: Incorrect 

Correct statement: Generally, surface ocean currents are formed in the equatorial region as well as polar region.

 (d) Ocean currents hold great importance

for human life.

Ans: Correct

 (e) The movement of icebergs is not

 dangerous for water transport.

Answer:Incorrect.

Correct statement: The movement of icebergs is dangerous for water transport.

 (f) Water becomes warm near Brazil due

to ocean currents. On the other hand, it

becomes cold near African coast. 

Answer:Incorrect.

Correct statement: Water becomes warm near Brazil due to ocean currents. Similarly, it also becomes warm near African coast.

Q 3. Explain the effect of -

 (a) Warm ocean currents on climate 

Ans: The amount of precipitation increases in the coastal region along with which the warm ocean currents flow.

Similarly, the temperature increases in the coastal region along with which the warm ocean currentcurrents

 (b) Cold ocean currents on the movement

of icebergs 

Ans: Due to cold ocean currents, icebergs are moved away from the polar regions.

These icebergs come along the marine routes and prove hazardous to the ships.

 (c) The shape of the coast line on ocean

currents

Ans: The extended parts of coastline acts as an obstacle for ocean currents.

The extended parts of coastline alters the direction and velocity of ocean currents.

 (d) Meeting of warm and cold ocean

currents

Ans: Dense fog is found in the meeting point of warm and cold ocean currents. Algae, plankton, etc. fish food grow on a large scale in these areas.

Fish come in these areas on a large scale and breed. Therefore, extensive fishing grounds are found in the areas where warm and cold ocean currents meet.

 (e) The transportational capacity of ocean

currents

Ans: The transportation capacity of ocean currents alters the amount of precipitation and temperature in the coastal regions along with which they flow.

The transportation capacity of ocean currents leads to transfer of warm water to the bottom from the surface and cold water to the surface from the bottom.

 (f) Deep ocean currents

Ans: Deep ocean currents leads to transfer of warm water to the bottom from the surface and cold water to the surface from the bottom.

Deep ocean currents thus leads to redistribution of sea water.

Q 4. Look at the map of ocean currents and answer the following :

 (a) How does the Humboldt current affect

the climate of the South American

coast?

Ans:Humboldt current is a cold ocean current and so it decreases the amount of precipitation and temperature on the western coastal region of the South America.

 (b) In which oceans are counter equatorial

currents not observed and why? 

Ans: Counter equatorial currents are not observed in Arctic Ocean and Southern Ocean. These oceans are located near the polar regions. Therefore, the effects of trade winds is found to be less in these oceans Therefore, counter equatorial currents are not observed in these oceans.

 (c) Which currents are absent in northern

part of the Indian Ocean and why? 

Ans: Cold currents are absent in the northern part of the Indian Ocean. The northern part of Indian Ocean is included in the temperate zone. So cold currents are absent in the northern part of the Indian Ocean.

 (d) In which regions do the cold and warm

ocean currents meet? 

Ans: 

The cold and warm ocean currents S meet in the following regions:

North Atlantic Ocean (cold Labrador current and warm Gulf stream current)

North Pacific Ocean (cold Oyashio current and warm ! Kurishio current)

South Atlantic Ocean ! (cold Falkland current and warm Brazil current)

South Pacific Ocean (cold South Polar current and warm East Australian current)

Indian Ocean (cold South Polar i current and Agulhas Current)

Q 5. Answer the following questions:

 (a) What are the reasons responsible for

the formation of deep ocean currents? 

Ans: The temperature varies in various parts of ocean.

Similarly, the density of water in various parts of ocean is also found to be different.

The difference in the temperature and density of seawater leads to its circulation and the deep ocean currents are formed. This circulation is known as thermohaline circulation.

Thus, the difference in temperature and density of water in various parts of ocean are the reasons responsible for the formation of deep ocean currents.

 b) What is the reason behind the dynamicsof the ocean water? 

Ans: Planetary winds is the reason behind the dynamics of the ocean water.

 (c) How do winds give direction to the

ocean currents? 

Ans: Winds give clockwise direction to the ocean currents in the northern hemisphere and anti-clockwise direction to the ocean currents in the southern hemisphere.

 d) Why do the ports in the eastern coast of Canada freeze in winter? 

Ans: Labrador cold current flows along the eastern coast of Canada.

Due to Labrador cold current, the temperature of sea water near the eastern coast of Canada decreases.

Due to fall in temperature, the sea water along the eastern coast of Canada start freezing. As its effect, the ports in the eastern coast of Canada freeze in winter.