Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man

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Kerala State Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man

Ocean and Man Textual Questions and Answers

Question 1.
Identify the location of each ocean from the world map. List the straits, bays and the seas of each ocean with the help of an atlas.
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 1

Question 2.
The following table contains the names of some major islands and peninsulas in the world. With the help of an atlas find out the names of the oceans to which they below.
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 2

  1. Indian Ocean
  2. Indian Ocean
  3. Pacific Ocean
  4. Atlantic Ocean
  5. Atlantic Ocean

Question 3.
Complete the table using fig. 5.7 in textbook
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 3
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 4
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 5
Question 4.
The equatorial regions; record a high amount of salinity as compared to the polar regions why?
Answer:
The temperature is high in equatorial regions compared to polar regions. Density increases as temperature rises. High density is associated with high salinity. There is possibility of high evaporation in equatorial regions. That is why equatorial regions record high amount of salinity.

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Question 5.
Why is salinity is less at river mouths?
Answer:
Salinity is less at river mouths because of huge amount of freshwater added from hundred of rivers.

Question 6.
Which are the warm and cold currents of the Atlantic Ocean? Identify the continents near which they flow.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 6
Answer:

Warm currents Continents near which they flow
1. North Atlantic current 1. Europe
2. Gulf Stream 2. North America
3. Florida current 3. North America
4. North equatorial currents 4. South America & Africa
5. Equatorial counter currents 5. South America & Africa
6. South Equatorial currents 6. South America & Africa
7. Brazilian current 7. South America
Cold current Continent near which they flow
1. Labrador current 1. North America
2. West wind drift 2. South America
3. Benguela current 3. Africa
4. Canaries current 4. Europe of Africa

Question 7.
Complete the following table based on the currents of the Indian Ocean.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 7
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 8
Answer:

Currents Warm/Cold Direction
1. South equatorial current 1. Warm 1. From East to West
5. South West Monsoon current 5. Warm 2. From West to East
6. Agulhas current 6. Warm 3. From North to West
7. West Australian current 7. Cold 4. From South to North
8. West wind Drift 8. Cold 5. From West to East

Question 8.
You have learnt the uses of Oceans. Conduct a seminar on the topic ‘influence of Oceans in human life’.
Answer:
“Influence of Oceans in Human Life”
Oceans play significant role in the life of human beings. We cannot neglect oceans because oceans are useful in

  • Influencing our climate.
  • Providing mineral deposits.
  • Helping power generation.
  • Providing source of food.

We shall now explain the influence of Ocean in detail.
Climate:
Oceans have a decisive role in controlling the climate along the coastal regions. The sea breeze during the day and the land breeze in the night regulate the temperature over the coasts. Oceans play a part in the formation of weather phenomena like rain, wind, and cyclones. Generally, the coastal regions have moderate climate, whereas severe summer and winter prevail in regions away from the sea.
Oceans as a source of food:
Fish is an important item of food. Fishing is major
activity in Japan, Peru, China, Norway, and the United States of America. Marine organisms are the source of many medicines. They are used for the production of antibiotics, steroids, and vitamins.

Ocean and Man Model Questions and Answers

Question 9.
Nearly ………… % of earth’s surface area is covered with water.
Answer:
71%

Question 10.
Name the Oceans
Answer:
a) The Pacific Ocean
b) The Atlantic Ocean
c) The Indian Ocean
d) The Artie Ocean
e) The Antarctic Ocean

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Question 11.
Match the following

A B
Pacific ocean Southern ocean
Atlantic ocean Warton trench
Indian ocean Puerto Rico
Antarctic ocean Challenger Deep

Answer:

A B
Pacific ocean Challenger Deep
Atlantic ocean Puerto Rico
Indian ocean Warton trench
Antarctic ocean Southern ocean

Question 12.
Distinguish between bay and strait.
Answer:
The portion of the sea surrounded by land on three sides is called a bay. On the other hand, the narrow stretch of sea between two landmasses is known as strait.

Question 13.
Complete the table

Islands Peninsula
Sri Lanka
Maldives
Green land
Sumatra

Answer:

Islands Peninsula
Sri Lanka Indian Peninsula
Maldives Arabian Peninsula
Green land Alaska Peninsula
Sumatra Labrador Peninsula

Question 14.
Define Peninsula
Answer:
The landmasses surrounded by sea on three sides are called peninsula.

Question 15.
Identify the important features of seawater.
Answer:

  • Temperature
  • Salinity
  • Density

Question 16.
Where do you find the highest Ocean temperature?
Answer:
Between 10° latitudes on either side of the equator

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Question 17.
As we more away from the equator, temperature considerably.
a) Increases
b) Decreases
c) First increases and then decreases
d) Remains constant
Answer:
a) Increases

Question 18.
What is the reason for the variation in temperature over different latitudinal zones?
Answer:
Variation in the amount of insolation received on the earth is the major reason, The Ocean currents and winds also influence the temperature of seawater.

Question 19.
Define Salinity?
Answer:
The concentration of salt content in seawater is known as salinity.

Question 20.
The average amount of saltiness of seawater is
a) 2.5%
b) 3.5%
c) 4.5%
d) 5.5%
Answer:
b) 3.5%

Question 21.
Name the major contents of seawater
Answer:

  • Sodium chloride
  • Magnesium chloride
  • Magnesium Sulphate

Question 22.
Point out the conditions leading to variations in salinity.
Answer:

  • Salinity will be more in landlocked seas.
  • Salinity increases in areas of high evaporation.
  • Salinity decreases in areas where snow meltwater reaches in large quantity.
  • Salinity decreases at river mouths.
  • Heavy rainfall leads to reduction in salinity.

Question 23.
What causes movements in seawater.
Answer:
The density of seawater is not uniform everywhere. This is due to the variations in salinity and temperature of sea water. Density decreases as temperature increases, and it increases as salinity increases. You have understood that the temperature, salinity and the density of seawater are not uniform everywhere. These variations lead to movements in seawater.

Question 24.
Which are the movements of seawater.
Answer:

  • Waves
  • Tides
  • Ocean currents

Question 25.
What are sea waves?
Answer:
The up and down motion of the water along the surface of the sea is called sea waves.

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Question 26.
Mark the missing portion.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 9
Answer:

  1. WaveLength
  2. Crest
  3. Wave height
  4. Trough

Question 27.
Name the following:
(i) The summit of the wave
(ii) Bottom part of the wave
(iii) Distance between 2 adjacent crests
(iv) Vertical distance between the crest and the trough
Answer:
(i) Wave crest
(ii) Wave trough
(iii) Wavelength
(iv) Wave height

Question 28.
………. is the reason for waves.
Answer:
The friction exerted by winds on the ocean surface

Question 29.
As the speed of the wind increases, the strength of the wave
a) Decreases
b) Increases
c) Remains constant
Answer:
b) Increases

Question 30.
Name two damages caused by strong waves
Answer:

  • Cyclones
  • Shelving of shores

Question 31.
Some measures are taken to prevent damage and to protect the lives of people living in the coastal areas. Identify the measures.
Answer:

  • Depositing boulders along the seashore.
  • Construction of interlocking concrete structures (Pulimuttu)
  • Planting of mangroves.

Question 32.
Name the sea waves generated by earthquakes and volcanos
Answer:
Seismic sea waves or tsunami waves.

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Question 33.
Prepare a note on mud bank
Answer:
Mudbank is a phenomenon that develops in the Arabian Sea during the onset or the end of the monsoon season. Planktons grow luxuriantly in the turbulent muddy water along the seashore during the monsoon rains. Schools of fish such as shrimp, sardine, and mackerel arrive to feed on the planktons and the mud, giving fishermen a good catch. This phenomenon is known as mud bank.

Question 34.
What do you mean by tides?
Answer:
Tides are he periodic rise and fall of water level in the ocean.

Question 35.
Distinguish between high tide and low tide
Answer:
The rise in the level of ocean water is the high tide and the lowering of the water level is known as the low tide.

Question 36.
What are the reasons for tides?
Answer:
Tides are formed as a result of the gravitational pull exerted by the moon and the sun along with the centrifugal force due to the earth’s rotation.

Question 37.
‘ Illustrate with the help of a figure the occurrence of high tide and low tide.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 10
Answer:
The water level on the part of the earth facing the moon rises. The rise in water level due to the gravitational pull exerted by the moon leads to high tide. You might have noticed that the water level at the opposite side also has risen. The centrifugal force due to the earth’s rotation is the reason for the rise in water level here. It can be seen that the water level goes down at places located 90° away from the places of tidal influence. This is due to the draining of water towards the tidal regions. The phenomenon of fall of water level is known as low tide.

Question 38.
Point out the important effects of tides.
Answer:
High tides and low tides have many effects. Let’s have a look at them.

  • The debris dumped along the seashores and ports are washed off to the deep sea.
  • The formation of deltas is disrupted due to strong tides.
  • Brackish water can be collected in salt pans during high tides.
  • The fishermen make use of the tides for going and returning from the sea in catamarans.
  • Tidal energy can be used for power generation.
  • Ships can be brought to shallow harbors during high tides.

Question 39.
Prepare a note on ocean currents
Answer:
It is a type of seawater movement. Ocean currents are the continuous flow of seawater from one direction to another. They can be classified as warm currents and cold currents. Warm currents are the currents that flow from the tropical or subtropical regions towards the polar or subpolar regions. The water that flows in will be warmer than the water at the destination.

Similarly, cold currents are the currents that flow in from the polar or the subpolar regions towards the tropical or subtropical regions.In this case, the water that flow in will be colder than the water at the destination. The temperature and salinity of seawater varies from ocean to ocean. This difference leads to density difference in seawater. The difference in density is one of the factors that cause ocean currents.

Question 40.
Complete the chart.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 11
Answer:

  1. Warm currents
  2. Cold currents

Question 41.
What are the effects of ocean currents?
Answer;

  • Influence the climate of coastal regions.
  • Fog develops in the regions where warm and cold currents meet.
  • The regions where the warm and cold currents meet provide favorable conditions for the growth of fish.

Question 42.
Which are the mineral deposits in ocean.
Answer;

  • Iron ore
  • Coal
  • Petroleum
  • Natural gas

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Question 43
The oil field started in 1974 in Mumbai is known as
Answer:
Mumbai High

Question 44.
Name some countries where fishing is an important activity.
Answer:

  • Japan
  • Peru
  • China
  • Norway
  • USA

Question 45.
What are the medicinal user of marine organisms?
Answer:
Marine organisms help in production of :-

  • antibiotics
  • steroids
  • vitamines

Question 46.
Prepare a flow chart showing method of purifying seawater.
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 12

Let Us Assess

Question 47.
Which among the following statements is not related to the Indian Ocean?
a. The southern part of this ocean extends up to the Antarctic Ocean.
b. The average depth is more than that of the Atlan tic Ocean.
c. The Puerto Rico trench is situated in this ocean.
d. It ranks third in area.
Answer:
B & C are not related

Question 48.
which among the following places record the least salinity? why?
1. Land-locked sea,
2. Areas of heavy rainfall
3. Areas of high evaporation
Answer;
Landlocked sea. Because salinity increases in landlocked seas.

Question 49.
Is there any relation between the intensity of waves and the wavelength? substantiate
Answer:
The Intensity of waves is defined as the power delivered per unit area. The unit of intensity will be W.m2. The wave energy comes from simple harmonic motion of its particles. The total energy will equal the maximum kinetic energy. As intensity of waves increases the wavelength also increases.

Question 50.
High tide occurs twice a day. Explain this statement.
Answer:
The rise in water level due to the gravitational pull exerted by the moon leads to high tide. Tides can occur as two high waters and two low water each day. The tides are occurred by the gravitational. The moon’s gravity pulls the ocean surface closer to it and the moon makes two trips around the earth each day. Hence there in high tide twice a day.

Question 51.
Explain spring tides and neap tides with the help of diagrams.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 5 Ocean and Man 13
The sun, moon, and earth come in a straight line on full moon and new moon days. The tidal force will be intense due to the combined influence of sun and moon. As a result, the tides formed on these days will be stronger. These are known as spring tides. The moon and the sun will be at an angular distance of 90° from the earth after seven days from the full moon and new moon days. As the sun and the moon attract the earth from an angular distance of 90° the tides casued are weak. Such weak tides are known as neap tides. Note the positions of the earth, moon, and sun in the given diagram.

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Question 52.
Oceans play an important role in human life and environment. Justify.
Answer:
Influence of Oceans in human life
Oceans play significant role in the life of human beings. We cannot neglect oceans because oceans are useful in

  • Influencing our climate.
  • Providing mineral deposits.
  • helping power generation.
  • Providing source of food.

We shall now explain the influence of ocean in detail.

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