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World Geography MCQs – 06 (Oceans)

Oceans MCQs with answers and explanations for all examinations.

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1. The main cause of the origin of tides in the ocean are :

(a) Gravitational force of the sun
(b) Monsoon Climate
(c) Due to the force of gravity of both the sun and the moon
(d) Sea water streams

Correct Answer – (c) Due to the force of gravity of both the sun and the moon

  • The rhythmic rise and fall of ocean water twice in a day is called a tide. 
  • The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes the tides. 
  • As the sun is far away from the earth as compared to the moon, the gravitational pull of the sun is lesser over the Earth than the moon. This is the reason that the moon mainly determines the magnitude of the tide. 
  • The water of the earth closer to the moon gets pulled under the influence of moon’s gravitational force and causes high tide whereas the side opposite from the moon experiences low tide.

2. Which of the following benefits are related to high tide?

1. High tides help in navigation.
2. The high tides also help in fishing.
3. The rise and fall of water due to tides is used to generate electricity at some places.

(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) All of the above

Correct Answer – (d) All of the above

  • High tides help in navigation as they raise the water level close to the shores which helps the ships to arrive at the harbor easily. 
  • The high tides also help in fishing. More fish come closer to the shore during the high tide. This enables fishermans to get more catches. 
  • The rise and fall of water due to tides is being used to generate electricity in some places by harnessing this tidal energy.

3. Consider the following statements:

1. Spring tides are formed when the sun and the moon are in line with each other.
2. Neap tides are formed when the sun and the moon are at the right angle to each other.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2 

  • Both the statements are true.
  • Spring tides:
    • These are formed when the sun and the moon are in line with each other and pull the ocean water in the same direction.
    • This causes higher high tides and lowers low tides.
    • It can occur twice in a lunar month.
  • Neap tides:
    • These are formed when the sun and the moon are at the right angle to each other.
    • As the gravitational pull of the moon is canceled out by the gravitational pull of the sun to some extent, it causes lower high tides and higher low tides.

4. Consider the following statements regarding the Pacific Ring of Fire :

1. It is characterized by active volcanoes.
2. There are frequent earthquakes in this area.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2 

  • The Pacific Ring of Fire is a Circum-Pacific Belt along the Pacific Ocean characterized by active volcanoes and frequent earthquakes.
  • Its length is approximately 40,000 kilometers which consists of boundaries between several tectonic plates.
  • Mount Fuji, which is Japan’s most famous mountain and an active volcano, is part of Ring of Fire.
  • About more than 75 percent of earth’s volcanoes and 90 percent of earthquakes exist here.

5. The Mariana Trench is part of which among the following ocean :

(a) Pacific Ocean
(b) Atlantic Ocean
(c) Indian Ocean
(d) None of the Above

Correct Answer – (a) Pacific Ocean

  • The oceanic trenches are long and narrow depressions of the ocean floor.
  • The Mariana Trench is an oceanic trench situated in the western Pacific Ocean.
  • It is the deepest oceanic trench on Earth.
  • Its deepest point is called Challenger Deep.
  • Tonga Trench is located in the South Pacific Ocean and is the second deepest trench. Its deepest point is called Horizon Deep.

6. Consider the following statements regarding the Pacific Ring of Fire :

1. Planktons are found in continental shelves.
2. The continental shelf off the eastern coast of India is much wider than that of the western coast.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2

  • The Ocean floors are broadly divided into four major parts:
    • Continental shelf 
    • Continental slope
    • Abyssal plains
    • The ocean deeps
  • Continental shelf is the part of a continent that is submerged in a shallow level of water.
  • The shallow water on the Continental shelf allows sunlight to reach to the bottom and helps in growth of microscopic plants and animals called planktons. These planktons act as food for fishes.
  • The continental shelf off the eastern coast of India is much wider than that of the western coast.

7. Consider the following statements :

1. Coral reefs are generally found deep inside the seafloor or Abyssal plains.
2. Submarine Canyons are generally found on the continental shelf.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (b) 2 only 

  • Coral reefs need sunlight to survive hence they can exist only in the shallow water areas of continental shelf.
  • Coral reefs do not exist in seafloor or Abyssal plains.
  • Submarine Canyons are ‘steep sided valleys’ created on continental shelves and can extend till Continental slope.
  • They are similar to the gorges found on the continents.

8. The largest continental shelf of the world is located in which among the following oceans ?

(a) Pacific Ocean
(b) Atlantic Ocean
(c) Indian Ocean
(d) Arctic Ocean

Correct Answer – (d) Arctic Ocean

  • The largest continental shelf of the world is the Siberian Shelf in the Arctic Ocean.
  • It is 1500 kilometers in width.

9. Consider the following statements :

1. Continental slopes connect Continental shelf to Abyssal plains.
2. Abyssal plains are mostly flat.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2 

  • Continental slopes connect Continental shelf to Abyssal plains.
  • There are very few living organisms on the continental slopes as compared to the continental  shelf.
  • Abyssal plains are mostly flat and featureless plains existing on the deep ocean floor.
  • Abyssal plains cover more than 50% of Earth’s total surface.

10. Consider the following statements about the Submarine ridges :

1. They exist in deep ocean floors.
2. They are generally associated with earthquakes.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2 

  • Submarine ridges also known as mid-oceanic ridges exist in deep ocean floors(almost near the middle of the oceans ).
  • They are generally associated with frequent earthquakes and volcanism.

11. The volcanos rising above the ocean floor whose top gets flattened by erosion are called ?

(a) Seamounts
(b) Guyots
(c) Trenches
(d) None of the Above

Correct Answer – (b) Guyots

  • Majority of the volcanoes of the world are found in the seas.
  • They are scattered over the entire sea floor
  • The volcanos rising above the ocean floor whose top gets flattened by erosion are called Guyots.
  • The volcanoes rising above the ocean floor whose top is intact and sharp are called Seamounts.
  • In case when volcanoes rise above the sea, they create volcanic islands. Hawaii islands are examples of such islands.

12. Consider the following statements :

1. The oceans get heated and cooled slower than the land surfaces.
2. The temperature of Ocean surface water increases from the equator towards the poles.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (a) 1 only 

  •  The oceans get heated and cooled slower than the land surfaces. Due to this feature, areas lying near the sea experience moderate climate.
  • The temperature of Ocean surface water increases from the equator towards the poles. This is caused due to lower insolation received by the ocean surface from the equator towards the poles.

13. Consider the following statements :

1. Lagoon is a shallow body of sea water.
2. Coral Reefs need warm and shallow water to grow.

Which of the above statements are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) None of the Above

Correct Answer – (c) Both 1 and 2 

  • Lagoon is a shallow body of sea water or brackish water separated from the sea by a barrier.
  • The biggest lagoon in the world is in New Caledonia which is a French Pacific territory. 
  • It’s a UNESCO World Heritage Site and a major tourist destination. 
  • Coral Reefs need warm and shallow water to grow.
  • Due to high levels of biodiversity, they are also called ‘Rainforests of the sea’.
  • The largest Coral reef in the world is the Great Barrier Reef. 
  • It is located in Australia.

14. On the basis of temperature, oceans are vertically divided into how many parts ?

(a) 2
(b) 3
(c) 4
(d) 5

Correct Answer – (b) 3

  • Sea temperature decreases with increasing depth but the rate of decrease of temperature is not uniform.
  • On the basis of temperature, oceans are vertically divided into three parts:
  • Photic Zone or Euphotic Zone: 
    • Upper layer of the ocean till 100 meters
    • The temperature is almost constant
  • Thermocline: 
    • Lies between 100-1000 meters 
    • There is a steep fall in the temperature
  • Deep Zone: 
    • Below 1000 meters
    • The temperature is near 0 °C(slightly higher than zero).

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