Students can download Class 8 Geography Chapter 4 Hydrosphere Important Questions, KSEEB Class 8 Social Science Important Questions and Answers helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.
Karnataka State Syllabus Class 8 Social Science Geography Important Questions Chapter 4 Hydrosphere
Question 1.
What is hydrosphere?
Answer:
Hydrosphere is the component of the earth that contains all the water bodies on the surface of the earth. It is the combined mass of water found on the surface of the earth, underground, and in the air above the surface of the earth. 71% of the earth’s surface is covered with these water bodies.
Question 2.
Why is earth called’blue planet’or’watery planet’?
Answer:
The earth is called blue planet or watery planet because about 71% of the earth’s surface is covered with water.
Question 3.
Which are the major water bodies of the world?
Answer:
The major water bodies of the world are Pacific Ocean, Atlantic Ocean, Indian Ocean and the Arctic Ocean.
Question 4.
What are oceans?
Answer:
Oceans are large and deep expanse of water found between continents.
Question 5.
What is the difference between oceans and seas?
Answer:
Oceans are large and deep expanse of water found between continents. Seas are not as large as oceans. They are a part of the ocean extended or projected far inland.
Question 6.
What is a gulf? Give examples.
Answer:
Gulf is a part of an ocean or sea that has penetrated into the land. It is smaller than the sea. eg: the Gulf of Mannar, the Persian Gulf, the Gulf of Mexico, etc.
Question 7.
What is a bay? Give examples.
Answer:
Bays are small semi-circular water bodies partially surrounded by land. The depth, extent and size of bays varies from one to another. eg: Bay of Bengal, Hudson Bay.
Question 8.
Distinguish between strait and isthmus.
Answer:
Strait: A strait is a narrow strip of water body joining two large water bodies.
Isthmus: Isthmus is a narrow stretch of land mass joining two large land masses.
Question 9.
Mention the four major parts of the ocean floor.
Answer:
On the basis of characteristic features the ocean floor is divided into four parts. They are
- the continental shelf
- the continental slope
- the deep sea plain
- the ocean deep.
Question 10.
What is continental shelf?
Answer:
Continental shelf is a shallow area along the sea coast. This part is bordered by the sea coast on one side and continental slope on the other. The average depth of continental shelf is 100 fathoms (600 feet). The depth of the sea in this region gradually increases towards the continental shelf. The continental shelf is very important for fishing, aquaculture, navigation and extraction of minerals.
Question 11.
What is continental slope?
Answer:
This is the second part of the ocean floor and it is very steep. It is a link between continental shelf and deep sea plain. Submarine canyons are a special feature of this region.
Question 12.
Describe the deep sea plains.
Answer:
This is the vast plain found at the bottom of the sea floor. The deep sea plain is also known as ‘abyssal plain’ and it covers the largest area of the ocean floor. Sea mounts and guyots are found in this region.
Question 13.
What is ocean deep? Give examples.
Answer:
The ocean deep is also called ‘ocean trench’. It is the deepest part of the ocean floor. Some of the ocean deeps are the Challenger Deep of Mariana trench in the Pacific Ocean which is about 11,033 meters deep and is the deepest point of the oceans, Tonga trench, Kuril trench in the Pacific Ocean, etc.
Question 14.
What factors influence the temperature of oceans?
Answer:
The temperature of sea or ocean water varies according to latitude and depth of the ocean floor. The temperature of the ocean water near the equator is more than that of the temperature near the Arctic and Antarctic circles. Temperature of the ocean water decreases with increase in depth. This is because sunlight can penetrate into the ocean only up to a depth of 200 meters.
Question 15.
What is salinity?
Answer:
Salinity is the percentage of salts dissolved in sea or ocean water. The average salinity of ocean water is 35 PPT (that is, in every kilogram or 1000 grams of seawater, 35 grams are salt).
Question 16.
Why is sea water salty?
Answer:
The water flowing from land (rivers) to the sea carries many kinds of salts and deposits them in the sea or ocean. Due to high temperature water evaporates continuously and the salts remain in the sea or ocean. This continuous process over a long period of time has resulted in the accumulation of salts in the sea water making it salty.
Question 17.
Which are the different movements of ocean water?
Answer:
Ocean water has three types of movements. They are waves, currents and tides.
Question 18.
What are ocean currents? Name the different types of ocean currents.
Answer:
An ocean current is a regular or continuous movement of ocean water from one place to another. Ocean currents are of two types. They are – warm currents and cold currents.
Question 19.
Distinguish between warm currents and cold currents.
Answer:
Warm currents originate and flow from the equatorial regions to sub-polar regions. Cold currents originate in the polar regions and flow towards the equatorial region.
Question 20.
What factors influence ocean currents?
Answer:
Rotation of the earth, temperature, wind, salinity, shape of the land masses, etc., are the factors that influence ocean currents.
Question 21.
Which are the ocean currents of the North Pacific Ocean?
Answer:
In the North Pacific Ocean, North equatorial and Kuroshio warm currents, and Oyashio and California cold currents are the prominent ocean currents.
Question 22.
Name the ocean currents of the South Pacific ocean.
Answer:
The ocean currents of the South Pacific Ocean are – warm currents – South equatorial current and East Australian current, cold currents – Peru or Humboldt and West wind drift.
Question 23.
Name the North Atlantic ocean currents.
Answer:
Warm currents of North Atlantic – North equatorial current, Gulf stream, North Atlantic drift currents. Cold currents of North Atlantic – Labrador, Norwegian and Canary currents.
Question 24.
Name the warm and cold currents of South Atlantic ocean.
Answer:
Warm currents of South Atlantic – South equatorial current, Brazilian current. Cold currents of South Atlantic – Falkland and Benguela currents.
Question 25.
What is unique about the North Indian Ocean currents?
Answer:
The North Indian Ocean currents change their direction seasonally following the monsoons. During the South-west monsoon the currents flow in a south-west to north-east direction and during the North-east monsoon they flow in a north-east to south-west direction.
Question 26.
Which are the ocean currents of South Indian Ocean?
Answer:
The South Indian Ocean currents are Mozambique, Madagascar and Agulhas which are warm currents. The West Australian current is a cold current.
Question 27.
Name the major fishing grounds of the world.
Answer:
Honshu-Hokkaido (Japan), Grand Bank (Newfoundland, U.SA) and Dogger Bank (North Sea, in Europe) are the major fishing grounds of the world.
Question 28.
What are Odes? How are tides caused?
Answer:
Tides are the periodic rise and fall in the sea or ocean level. They are caused by the gravitational attraction of the moon, gravitational force of the sun, rotation of the earth, and centrifugal force of the earth.
Question 29.
Which are the different types of tides? Describe them.
Answer:
Tides are of two types – High tide (flood tide), and low tide (ebb tide). On the water bodies of the earth there are alternate high tides and low tides. Between one high tide and one low tide the time is 6 hours 13 minutes. Between one high tide and another, the time gap is 12 hours 26 minutes.
Question 30.
What are Spring tides and Neap tides?
OR
How are tides classified on the basis of the position of sun and moon?
Answer:
On the basis of position of sun and moon, tides are classified as Spring tides and Neap tides. The Spring tides take place when the earth, the moon, and the sun are in the same straight line. E.g., New Moon and Full Moon days. When spring tides take place, high tides are the highest and low tides are the lowest The Neap tides occur on the first quarter and last quarter days in the phase of the moon.
During Neap tides the earth and the sun are in the same straight line and the moon is at right angles to the earth. In this type of tide, the high tides are not very high and low tides are not very low.
Question 31.
State the differences between ocean currents and tides.
Answer:
An ocean current is a regular or continuous movement of ocean water from one place to another. It is caused by the rotation of the earth, wind, temperature and salinity of the ocean water.
Tides are periodic rise and fall in the sea or ocean level. They are caused by the gravitational attraction of moon, gravitational force of the sun, rotation of the earth, and centrifugal force of the earth.
Question 32.
Distinguish between spring tide and neap tide.
Answer:
Spring tide occurs when the sun, the moon and the earth are in the same straight line. They take place on New Moon and Full Moon days. During spring tides the high tides and low tides are at their maximum.
Neap tide occurs on the first quarter and last quarter days of the moon’s phases. During the neap tide the sun and the earth are in the same straight line and the moon is at right angles to the earth. During neap tides the high tides are not very high and low tides are not very low.
Question 33.
What are the uses of tides?
Answer:
Tides are useful to mankind in different ways:
- Tides help in navigation.
- They help in the location of ports and harbours.
- They help to keep the harbours clean.
- They help in fishing.
- They also help in generating energy (tidal energy) which is converted into electricity.
Question 34.
How can we conserve the oceans?
Answer:
The following are the important methods of conservation of oceans:
- Oil transportation should be done through pipelines.
- Nuclear waste should not be dumped in oceans.
- Petrochemical industries in the coastal regions must avoid discharge of effluents into the sea.
- Dumping of any waste near the ports and harbours must be controlled.
- Ore deposition and mineral exploitation along the coast must be controlled.
- Exploitation and destruction of beaches must be controlled.
Question 35.
Define the following:
Answer:
1. Continental shelf:
Continental shelf is a shallow area along the sea coast. This part is bordered by the sea coast on one side and continental slope on the other.
2. Salinity:
Salinity is the percentage of salts dissolved in sea or ocean water.
3. Warm and cold currents:
Warm currents are currents that originate and flow from the equatorial regions to sub-polar regions.Cold currents are currents that originate in the polar regions and flow towards the equatorial region.
4. High tide and low tide:
Tides are caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth. High tide is when the tide or sea water level is at its highest. Low tide is when the tide or sea water level is at its lowest. Generally, high tide and low tide both occur twice a day, separated by a roughly six-hour time-gap between them.
5. Benguela current:
Benguela current is a branch of the South Atlantic ocean current. It is a cold current that flows northward in the South Atlantic Ocean along the west coast of southern Africa.
6. Tides:
Tides are periodic rise and fall in the sea or ocean level.
Multiple Choice Questions
Question 1.
Since nearly 71 percent of the earth’s surface is covered by water it is called
(A) living planet
(B) blue planet
(C) unique planet
(D) strange planet.
Answer:
(B) blue planet
Question 2.
The largest ocean is
(A) Pacific Ocean
(B) Atlantic Ocean
(C) Arctic Ocean
(D) Indian Ocean.
Answer:
(A) Pacific Ocean
Question 3.
A narrow strip of water body joining two large water bodies is called
(A) Gulf
(B) Bay
(C) Strait
(D) Isthmus.
Answer:
(C) Strait
Question 4.
A narrow stretch of land mass joining two large land masses is
(A) Bay
(B) Gulf
(C) Strait
(D) Isthmus.
Answer:
(D) Isthmus.
Question 5.
The Suez Canal connects the Mediterranean Sea with the
(A) Arabian Sea
(B) Red Sea
(C) Black Sea
(D) Persian Gulf.
Answer:
(B) Red Sea
Question 6.
The deepest point of the oceans is ________ in the Pacific Ocean near Philippine Islands.
(A) Tonga trench
(B) Kuril trench
(C) Challenger deep
(D) Mariana trench.
Answer:
(C) Challenger deep
Question 7.
The Continental shelf is useful for
(A) fishing
(B) production of electricity
(C) mining
(D) tourism.
Answer:
(A) fishing
Question 8.
The regular movement of ocean water in a particular direction is called
(A) wave
(B) ocean current
(C) tide
(D) low tide.
Answer:
(B) ocean current
Question 9.
Which one of the following is a warm current?
(A) Falkland current
(B) Labrador current
(C) Benguela current
(D) Gulf stream.
Answer:
(D) Gulf stream.
Question 10.
Which one of the following is a cold current?
(A) Brazilian current
(B) Gulf stream
(C) Labrador current
(D) Kuroshio current.
Answer:
(C) Labrador current
Question 11.
The tide that occurs on new moon and full moon days is
(A) Neap tide
(B) Spring tide
(C) High tide
(D) Low tide.
Answer:
(B) Spring tide
Fill Up In The Blanks
- The average depth of the Continental Shelf is 100 fathoms
- One fathom is equal to 6 feet.
- The deepest place in the Pacific Ocean is Challenger Deep
- The average salinity of the ocean water is 35 ppt
- Spring tides occur during full moon.
- A narrow strip of land connecting two large masses of land is called Isthmus
- The deep sea plains are also called abyssal plains.
- Sunlight can penetrate into the ocean only up to a depth of 200 meters.
- The lake with the most saline water in the world is Lake Van in Turkey.
- When the earth and the sun are in a straight line and the moon is at right angles to the earth, neap tide occurs.
Match The Following
Question 1.
| A | B |
| a. Fathom | 1. Deep sea plains |
| b. Oyashio | 2. Eastern Coast of U.S.A. |
| c. Gulf stream | 3. Cold current |
| d. Sea mounts | 4. Indian ocean current |
| e. Agulhas current | 5. Depth of ocean |
Answer:
a – 5, b – 3, c – 2, d – 1, e – 4.
Question 2.
| A | B |
| a. North Pacific Ocean | 1. Agulhas current |
| b. South Pacific Ocean | 2. Benguela current |
| c. North Atlantic Ocean | 3. Kuroshio current |
| d. South Atlantic Ocean | 4. East Australian current |
| e. South Indian Ocean | 5. Labrador current |
Answer:
a – 3, b – 4, c – 5, d – 2, e – 1.
Question 3.
| A | B |
| a. Dead Sea | 1. Warm current |
| b. Gulf of Mannar | 2. Ocean deep |
| c. Ocean trenches | 3. North Sea (Europe) |
| d. Kuroshio | 4. India |
| e. Dogger Bank | 5. Jordan |
Answer:
a – 5, b – 4, c – 2, d – 1, e- 3.