Water Bodies
1. Match the following.
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a. Amazon |
i. Three Georges Dam. [d] |
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b. Nile |
ii. Gangotri Glacier. [c] |
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c. Ganga |
iii. Black Sea. [f] |
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d. R. Yangtze |
iv. Longest river of Europe. [j] |
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e. R. Mississippi |
v. Arabian Sea. [h] |
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f. R. Danube |
vi. Selvas. [a] |
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g. R. Ob |
vii. China. [i] |
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h. R. Indus |
viii. North America. [e] |
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i. R. Hwang Ho |
ix. Longest river in the world. [b] |
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j. R. Volga |
x. Arctic Ocean. [g] |
2. Answer in one or two words.
a. The deepest point of the Earth and its location.
= Mariana Trench under the Pacific Ocean;
b. A group of islands in the Pacific Ocean.
= Archipelago;
c. The ocean that is busiest of all oceans.
= Atlantic Ocean;
d. The ocean surrounding the north polar and south polar regions respectively.
= Arctic Ocean; Southern Ocean;
e. The largest saltwater lake of the world.
= The Caspian Sea;
f. A river in England that forms an estuary.
= Thames;
g. The famous waterfall between Lake Erie and Lake Ontario in North America.
= Niagara Falls;
h. The deepest freshwater lake of the world.
= Lake Baikal;
i. A large lake near the African Rift Valley.
= Lake Victoria;
j. The largest freshwater lake of Europe.
= Lake Ladoga;
3. Differentiate between :
a. Bays and gulfs.
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Bay |
Gulf |
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i. Sea water enclosed by land on three sides leaving a wide mouth is
called a bay. |
i. Gulf is a water body that enters deep inside the land. |
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ii. Example :- Bay of Bengal. |
ii. Example :- The Gulf Of Mexico. |
b. Seas and oceans.
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Seas |
Oceans |
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i. Seas are similar to ocean, but are smaller in size. |
i. Oceans are far more bigger than the seas. |
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ii. They are of two types – marginal sea and inland sea. |
ii. They are huge water bodies. |
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iii. Example: - Caribbean Sea. |
iii. Example :- Pacific Ocean. |
c. Marginal seas and inland seas.
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Marginal Seas |
Inland Seas |
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i. Marginal seas are large water bodies along the continental edges or
margins. |
i. Some lakes are too big for their size and are termed as inland
seas. |
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ii. They may be connected with the ocean alongside. |
ii. They are not connected with any ocean. |
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iii. Example :- Red Sea is a marginal sea of the Indian Ocean, it
lies between Africa and Asia. |
iii. Example :- The Caspian Sea. |
d. Deltas and estuaries.
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Deltas |
Estuaries |
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i. Deltas are the triangle-shaped alluvial deposits at the mouth of
the river. |
i. Estuaries are the open river mouth at the sea. |
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ii. These are the islands at the mouth of the river. |
ii. There are no islands at the Estuaries. |
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iii. Example :- the deltas of Ganga and Nile. |
iii. Example :- estuaries of Thames of England. |
e. Rainforest and mangrove forest.
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Rain forest |
Mangrove Forest |
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i. These are natural vegetation found in the river basins. They depend
on the rain water. |
i. These are natural vegetation found in the coastal side where the
water is saline. They depend on the sea water. |
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ii. They do not have breathing roots. |
ii. They have breathing roots to absorb oxygen from the air. |
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iii. Example :- Amazon Rain Forest. |
iii. Example :- Sundarbans Mangrove Forest. |
4. Give reason to explain each of the following.
a. Fresh water is extremely precious to us.
= Fresh water is extremely precious to us because lakes, ponds and rivers contain fresh water and occupy only 0.5 per cent of the Earth's surface. It is this fresh water that is indispensable for all organisms, both plants and animals.
b. Water vapour changes to water droplets in the upper atmosphere.
= Water vapour changes to water droplets in the upper atmosphere because the level of atmosphere is colder and it cools and condenses the water vapour into tiny water droplets.
c. The Atlantic coastline has several natural harbours.
= The Atlantic coastline has several natural harbours because the coastline of Europe and North America are highly indented and irregular in shape.
d. Waterfalls are common in mountainous areas.
= When water of the river falls from the edge of the mountain it causes waterfall. The physical feature of the mountains help to form waterfalls.
5. Answer the following questions.
a. What do you mean by hydrosphere?
= The Liquid water component of the Earth including the oceans, seas, lakes, ponds, rivers and streams together forms the hydrosphere.
b. i. Name the chief sources of fresh water on our planet.
ii. Name the oceans of the world in the order of their respective sizes.
= i. The chief sources of fresh water on our planet are - lakes, ponds and rivers. They occupy only 0.5 per cent of the Earth's surface.
ii. The names of the ocean of the world in the order of their respective sizes are - The Pacific Ocean, The Atlantic Ocean, The Indian Ocean, The Arctic Ocean.
c. Why is Earth called the 'Blue Planet'?
= The Earth is called the 'Blue Planet' because water bodies cover nearly 71 per cent of its surface.
d. Where does the rainwater go?
= Some of the rain water slips underground, some fills up depressions to form lakes, while others just flow into the rivers and streams, which carry water to the oceans.
e. With the help of a diagram, give a detailed explanation of the hydrological cycle.
= Most of the world's water is being recycled by this continuous process called the water cycle.
❐ The sun heats up the water bodies. The water evaporates as water vapour; which being light in weight, rises in the air.
❐ On reaching the higher, colder levels of the atmosphere, it cools and condenses into tiny water droplets that join to form clouds.
❐ When the clouds becomes too heavy and can not remain suspended in the air; it comes down as precipitation such as rain or snow. Rain is the biggest source of fresh water on the Earth.
❐ Some of the rain water slips underground, some fills up depressions to form lakes, while others just flow into the rivers and streams, which carry water to the oceans.
❐ The cycle is then repeated.
The Hydrological Cycle
f. Name the continents bordered by the Pacific Ocean. Name the ocean that it links to in the north.
= The Pacific Ocean is bordered by North America and South America in the east and Asia and Australia in the west.
In the north, it is linked to the Arctic Ocean.
g. Name the ocean that shaped like the letter 'S'. Which are the continents that lie to its east and west?
= The name of the ocean that shaped like the letter 'S' is Atlantic Ocean.
The Atlantic borders North America and South America on the western side, and Europe and Africa on the eastern side.
h. Why is the Indian Ocean so named? Which are the continents surrounding it in the west, north and east?
= The Indian Ocean is named after India, indicating the strategic location of the country at the head of the ocean.
The northern part of the Indian Ocean is surrounded by Africa in the west, Asia in the north and Australia in the east.
i. Explain how oceans influence the climate of a place.
= Ocean currents play a major role in shaping the climate on the Earth. Warm ocean currents keep cold coast areas ice-free and also bring in moist winds that shed rain. Cold ocean currents, on the other hand, make a place colder and drier.
j. Explain with a suitable example how ocean currents influence the development of rich fishing grounds.
= The meeting of the cold and warm ocean currents brings rich fish food called planktons, and hence these areas develop as ideal fishing grounds. For example, Grand Banks off the coast of Newfoundland in North America is the meeting place for the cold Labrador and the warm Gulf Stream currents.
k. Name the types of renewable energy that may be obtained from oceans. What minerals do we get from these water bodies.
= The types of renewable energy that may be obtained from oceans are - tidal energy and ocean thermal energy.
Oceans have vast reserves of minerals such as petroleum, magnesium, bromine and salt.
l. Explain the following giving suitable examples for each:- ❐ Gulf ❐ Bay ❐ Strait
= ❐ Gulf : Gulf is a water body that enters deep inside the land. The Gulf of Mexico, Gulf of Bothnia, Gulf of Aden and Gulf of Kutch are examples of Gulf.
❐ Bay: Sea water enclosed by land on three sides leaving a wide mouth is called a bay. The best example is the Bay of Bengal lying to the east of the Indian peninsula.
❐ Strait: Sometimes a narrow channel of sea water may separate two large land masses and join two large water bodies. This is known as a strait. Example:- The Strait of Gibraltar separates the continents of Europe and Africa and links the Atlantic Ocean with the Mediterranean Sea.
m. What are lagoons? Give an example.
= Lagoons are lakes with a narrow opening to the sea. They are separated from the sea by a sandbar or a coral reef or a spit. Lagoons such as Chilika in the state of Odisha in India is an example of such lagoon.
n. Explain the upper course of a river.
= Rivers begin their journey from the mountains. Meltwater from glaciers, springs or rainwater give rise to rivers. The river is young as it moves across the mountains. It has a speedy course and therefore cuts out deep V-shaped valleys called gorges or canyons. It forms waterfalls when it falls from the edge of the mountain. This stage of the river is called the upper course.
o. How are canyons formed?
= The river is young as it moves across the mountains. It has a speedy course and therefore cuts out deep V-shaped valleys called gorges or canyons.
p. Explain the formation of flood plains.
= During the monsoon, the river often floods its banks. The water spreads far and wide. When this water recedes, it leaves behind rich silt. In this way, flood plains are formed.
q. How are meanders formed?
= As the river comes out of the mountains, it enters the flat, levelled plains where its speed is no more as rapid as before. This stage is called the middle course. Now, the river swings from side to side forming bends known as meanders.
r. What are the main characteristics of a river in its old stage?
= As a river nears the sea, it reaches its old stage or the lower course. The main characteristics of a river in its old stage are:
❐ Its flow becomes sluggish even further.
❐ Often it begins to deposit the silt and sand in between the course of its flow.
❐ This sometimes leads to the formation of permanent river islands.
❐ The river now branches out into a number of narrow channels or distributaries as it cannot carry the large volume of water.
s. State two ways in which lakes are useful to humans?
= ❐ Lakes act as reservoirs to hold excess flood waters during monsoons. this water is often used for domestic purposes, for example, Powai Lake in Mumbai.
❐ Lake sites often develop as major tourist attractions because of their scenic beauty.
t. Give two reasons why rivers are valuable to the farmers.
= Rivers play a major role in farmers' lives. The two reasons why rivers are valuable to the farmers are :
❐ Rivers bring fresh silt to make fertile plains, which are excellent for growing crops.
❐ The water of river is used to irrigate agricultural fields. This is especially important for a country like India, which has to grow huge quantities of food grains for its large population.
u. Explain how human activities are degrading water bodies all over the globe.
= Water bodies are fast degenerating primarily due to human activities some of which ate enumerated below:
Household wastes: Domestic wastewater is mixed with other wastes such as plastic, detergent, animal dung and human excreta and is together known as municipal waste. This pollutes water bodies.
Industrial wastes: Factories produce toxic wastes containing heavy metals such as lead and mercury along with synthetic compounds, which when discharged into water bodies, pollute the water and cause irreparable harm to aquatic creatures.
Agricultural wastes: Agricultural wastes mostly consists of fertilisers and pesticides. They may be carried off from the farms to the rivers and lakes as surface runoff during rains or floods. They pollute the aquatic ecosystem by promoting rapid growth of algae and subsequent depletion of oxygen in water.
Oil spills: Crude oil is transported across oceans in tankers. Accidents and leakages often cause oil spills that damage the marine ecosystems. Offshore drilling operations also contribute to oil spill.