GEOGRAPHY – CLASS 7

Chapter 1 –Representation of Geographical Features

Kindly use the following link and watch the videos from the

YouTube to understand the lesson.

1. https://www.youtube.com/watch?v=h--rg-_YLwc&t=2s

2. https://www.youtube.com/watch?v=DvtDBgA1M0o

3. https://www.youtube.com/watch?v=Dzp4pOad74g&t=440s

4. https://www.youtube.com/watch?v=MFZ1M2p1Do0&t=225s

To be written in the note book

1. Fill in the blanks: (Copy the sentences from the text book)

1. Representative Fraction

2. Larger

3. Smaller

4. Cultivable

5. Settlements

B. Write ‘A for agree and ‘D’ for Disagree (Copy the sentences from the text book) 1. Agree

2. Agree

3. Agree

4. Agree

5. Disagree

C. Answer in brief:

1. What is the significance of the symbol -x-x-x? Ans: State boundaries

2. What is radial drainage? Ans: A drainage pattern in which consequent streams radiate or diverge outward, like the spokes of a wheel, from a high central area; it is best developed on the slopes of the hills or of a volcanic cone.

3. What does the symbol ---------- stand for? Ans: Narrow Gauge- the distance between the rails is 0.7m. 4. What is the main object of the topographical maps?

Ans: The main object of the topographical maps or survey sheets is to represent a colourful, vivid picture of an area as it actually exist during the survey in a miniature form.

5. What do you mean by distance? Ans: Distance is a space between the two points. It may be long distance or short distance. 6. What do you mean by brackish?

Ans: Brackish is water having more salinity than freshwater, but not as much as seawater. It may result from mixing seawater with fresh water.

D. Answer on detail: 1. What do the following colours on topographical sheets signify: Green, Red, Brown, Yellow?

Green: Forest areas or lowland areas.

Red: Permanent huts, settlements, towns and cities.

Brown: Contour lines, their heights and relief features like mountains, hills.

Yellow: Cultivable land, Plateaus, deserts and plains.

2. State the differences between large scale and Small scale maps.

3. Explain the following terms:

Verbal Scale or Statement Scale : Verbal scale expresses in words a relationship

between a map distance and a ground distance. For example: 1 cm on the map represents

50 km on the ground.

Representative Fraction or R.F.: A method of scale of a map or plan expressed as

a fraction showing the ratio between the distance on the map to the distance on the

ground.

Linear Scale: it represents the relationship between the distance on the map and

distance on the ground. It is drawn according to the statement in such a way that the

distance can be calculated most accurately on the map.

4. Define the following:

Causeway: A raised road or track across low or wet ground.

Small scale maps Large scale maps

These maps show a larger area in less detail.

These maps show a small area in more detail.

Various relief features like seas, mountains, plateaus, countries, etc. are shown on these maps.

These maps show the details of cities, towns or villages.

Examples include wall maps or atlas maps.

Examples include guide maps or topographical maps

The scale may be 1cm = 100 cm

The scale may be 1 cm = 50 m or 1 km

Broad gauge: The distance between two rails is called a gauge.

Dams: is a man-made structure built across a river to control the overflow of water.

Sand dunes: Sand features shown in brown on the map formed due to wind

deposition in the

Broken ground: Generally found along the banks of a stream or river in arid regions

where the top soil gets easily eroded due to flooding during rainy season. This type

of land is uncultivable.

5. State the two ways of measuring distances.

Ans: Measuring distances in a straight line: Use a ruler to ensure the distance between the two places. Measure the distance of a curved road, river or canal: If the line that you're trying to measure is quite curved, use a string to determine the distance, and then measure the string with the help of ruler.

6. What is the importance of conventional signs and symbols on a map?

Conventional sings are the most important components on the map as it is not possible to draw on the map the actual size and shape of different features such as railway lines, roads, trees, etc.

These symbols give us a lot of information in a limited space. With the help of these symbols, maps can be drawn easily and are easy to read.

A variety of features both man-made and natural can be depicted on the map with the help of conventional signs and symbols, e.g. mountains, peaks, rivers, roads, buildings, etc.

These symbols are used to give maximum information in detail about the areas using appropriate colours.

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Chapter 2 –ATMOSPHERE

Kindly use the following link and watch the videos from the

YouTube to understand the lesson.

1. https://www.youtube.com/watch?v=wMKStZr4rYc

2. https://www.youtube.com/watch?v=o6i1SS4sjDA

3. https://www.youtube.com/watch?v=t7Pa2OZigEU

4. https://www.youtube.com/watch?v=zvjPW8pXvc8

A. Fill in the blanks: (Copy the sentences from the text book)

1. 1. 78%, 21%, 1%

2. Wind

3. Temperature

4. Humidity

5. Fossil fuels

B. Write ‘A’ for Agree and ‘D’ for Disagree

1. Agree

2. Disagree

3. Agree

4. Disagree

5. Agree

C. Answer in brief:

1. Which layer of the atmosphere is called ozonosphere?

Ans: Stratosphere

2. Mention a factor on which air pressure depends?

Ans: Altitude

3. What is the percentage of oxygen in the atmosphere?

Ans: 20.95%

4. Mention a few greenhouse gases.

Ans: Carbon dioxide, methane, Chlorine

D. Answer in detail:

1. Where do you find the ozone layer? How is it getting depleted?

Ans: The Ozone layer is found in Stratosphere. Ozone-layer is getting depleted because of excessive use of man-made compounds containing both fluorine and chlorine. The main reason being CFC molecules are made up of chlorine, fluorine and carbon atoms which are extremely stable. This extreme stability allows CFC's to slowly make their way into the stratosphere.

2. State the effects of ozone depletion on earth.

Because of the depletion of ozone layer the ultraviolet rays of the sun will not be absorbed.

As a result, an increasing amount of ultraviolet radiation reaches the earth which causes damage to marine life, human beings and plant life.

As a result of the depletion of ozone layer, there will be increase of skin cancer and cataract. The body will be exposed to a number of infectious diseases.

Plant and animal planktons which form the foundation of vast oceanic food chain, will be killed or destroyed.

3. Briefly discuss the impact of global warming.

Climate change: Global warming is the slow increase in the average temperature of the earth’s atmosphere because an increased amount of the energy (heat) striking the earth from the sun is being trapped in the atmosphere and not radiated out into space. Increase in temperature will melt the ice sheets and rise of sea level.

Changes of oceanic condition: there will be a great change in the oceanic condition. The increased levels of carbon dioxide have led to acidification of ocean. This will affect the marine life.

Effects on Flora and Fauna: Global warming will lead to extinction of flora and fauna. There is a risk of extinction of 30% of plants and animals by 2050 if temperature increases.

Destruction of Ecosystem: Because of the increase of carbon dioxide in the atmosphere, the total ecosystem will be destroyed.

Bleaching of Corals: Bleaching of corals is due to the loss of microscopic algae which gives both colour and nourishment to the corals of the seas and oceans.

4. What steps should be taken to reduce global warming?

Industrial pollution should be reduced.

Uses of Solar Energy: You should convert your heating system to the solar energy,

in this way you can save electricity, money and your environment from global

warming.

Plant Trees At Home: If you have placed at the front or back side of your home,

trees shading, can make your home cold during summer. Since trees absorb carbon

dioxide, so reduce the carbon dioxide in your surroundings.

Switch off Electric Appliances: When electric appliances are not in your use, then

plug them off, because they use some energy even in off position.

Driving of motor cars should be minimized to reduce the percentage of carbon

monoxide in the air.

5. What is greenhouse effect? What are its consequences?

The greenhouse effect: Is a problem caused by increased quantities of gases such

as carbon dioxide in the air. These gases trap the heat from the sun, and cause a

gradual rise in the temperature of the Earth's atmosphere.

Consequences of greenhouse effect:

1. As a result of rise in temperature of the earth due to greenhouse effect, the

ocean will warm up and sea level will rise flooding low-lying regions.

2. In temperate region, the winter will be shorter and warmer, summer will be

hotter and longer.

3. There will be enormous increase in rainfall, but the problems of desertification,

drought and soil erosion.

4. The tropic may become wet and the subtropics which are already dry, are

expected to be drier.

6. What are the objectives of the GEF?

Protection of biological diversity on earth.

Protection of international water.

Reduction of ozone layer depletion.

7. Mention the chief characteristics of stratosphere.

This layer lies above the tropopause and extends up to 50 km above the surface of the Earth.

This layer is free from any weather related phenomena.

The temperature remains constant in the lower levels of the stratosphere but increases with further height.

Ozone layer lies within the stratosphere. Ozone is generally found between the altitudes of 20 and 50km.

The upper limit of the stratosphere is known as stratopause.

Picture Study:

1. In which layer is the aeroplane flying? – Troposphere 2. In which layer do you see the hot air balloon? – Troposphere 3. Which layer causes the meteors to burn up? – Mesosphere 4. In which layer of the atmosphere do artificial satellites orbit the earth? Exosphere

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GEOGRAPHY – CLASS 7

Chapter 3 –Weather and Climate

Kindly use the following link and watch the videos from the

YouTube to understand the lesson.

https://www.youtube.com/watch?v=46HOISGNdkQ https://www.youtube.com/watch?v=EHNsvoqiOVk https://www.youtube.com/watch?v=GG7vxt8AgEA https://www.youtube.com/watch?v=46HOISGNdkQ&t=58s A. Fill n the blanks: (Copy the sentences from the text book)

1. Atmosphere

2. 30 to 35

3. Anemometer

4. Aneriod barometer

5. Nimbus clouds

6. Isohtes

B. Write ‘A’ for Agree and ‘D’ for Disagree. (Copy the sentences from the text book)

1. Disagree

2. Disagree

3. Agree

4. Agree

5. Disagree

C. Answer in brief.

1. Mention two elements of weather. Ans: Temperature and atmospheric pressure

2. What is climate? Ans: Climate means the usual condition of the temperature, humidity, atmospheric

pressure, wind, rainfall, and other meteorological elements in an area of the Earth's

surface for a long time. In simple terms climate is the average condition for about

thirty years.

3. What is hygrometer? Ans: A hygrometer is an instrument used to measure the amount of humidity and water Vapour of the atmosphere. 4. What is anemometer? Ans: An instrument for measuring the speed of the wind D. answer in detail: 1. Differentiate between weather and climate.

Weather Climate

Weather is the day to day condition of the atmosphere at any place for a short period.

Climate is the aggregate of atmospheric conditions for large period- 30 – 35 years.

Weather depends upon the dominant elements at a particular time-say rainfall or temperature.

But climate is the composite picture of all the elements spread over a large period.

Every type of weather can occur at the same place. But a particular

Weather refers to a particular place But climate refers to particular area.

Weather is uncertain and we can only forecast for a short time ahead.

But climate has a high degree of accuracy and it is similar year after year.

2. Explain the use of the Hygrometer.

To identify the humidity in the environment.

Use to identify water vapour present in the gaseous mixture.

Use to identify the moisture content in the environment.

Used in a various manufacturing process.

Used as a weather predictor.

Used to identify the % of relative humidity.

3. What are the two types of barometer? Explain briefly.

1. Simple Barometer

2. Aneroid Barometer

Simple Barometer or Mercury Barometer: It consists of a long glass tube filled with mercury. It is sealed at the upper end and open the lower end.

An aneroid barometer is made without fluid. It consists of a small, flexible metal box called an aneroid capsule, which is made from an alloy of beryllium and copper. It expands when the pressure is low and gets compressed when the pressure is high. There is a scale to indicate the atmospheric pressure.

4. Name the elements of weather and discuss any two of them in short. 1. Temperature 2. Precipitation 3. Wind direction 4. Wind speed 5. Clouds 6. Atmospheric pressure 7. Humidity

1. Temperature: it is the term used to express the intensity or degree of heat. The sun is the only natural source of heat energy of the earth. Insolation is the total amount of solar energy received by the surface of the earth.

2. Atmospheric pressure: The air has weight and it exerts pressure. The atmospheric pressure is the pressure that the atmosphere exerts on the surface of the earth. Atmospheric pressure is measured with a barometer.

5. Mention the types of clouds. Write a brief explanation of each type.

Nimbus clouds: These art h real rain clouds – thick, dark and black and spread out layers. They cause continuous rain or snow.

Stratus clouds: These are sheet-like clouds that spread out over the whole sky. They are uniformly grey and dull.

Cumulus clouds: these are cauliflower-shaped clouds that have great vertical height and a flat base. They cause rainfall with lightning and thunder and are usually white or grey in colour.

Cirrus clouds: these are feathery, fibrous clouds which form at very high levels of 5 to 10km.

6. State the use of rain gauge.

A rain gauge is an instrument we can use to measure the amount of rainfall in any area receives in a given time period.

A rain gauge is a simple instrument. Basically it looks like a transparent cylinder with markings. We can read the amount of rainfall in inches or millimetres. decisions.

Picture Study: 1. Rain Gauge 2. Precipitation 3. The rain gauge acts like a measuring cup to measure the amount of precipitation in a certain area. Using a rain gauge allows meteorologists to know exactly how much rain has fallen, allowing them to gauge exactly how much moisture is within the soil.

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GEOGRAPHY – CLASS 7

Chapter 4 –Weathering and Soil formation

Kindly use the following link and watch the videos from the

YouTube to understand the lesson.

https://www.youtube.com/watch?v=Hj3ihz_BFSo https://www.youtube.com/watch?v=5P-Uecqt6-8 https://www.youtube.com/watch?v=hihDWPQ2EHo

A. Fill in the blanks: (Copy the sentences from the text book)

1. Decomposition or disintegration

2. Three

3. Three

4. Horizontal

5. Removal or washing away

6. Soil profile

B. Write ‘A for agree and ‘D’ for Disagree (Copy the sentences from the text book) 1. Disagree 2. Disagree 3. Disagree 4. Agree 5. Agree

C. Answer in brief: 1. Mention the types.

Igneous rocks

Sedimentary rocks

Metamorphic rocks

2. What are the main components of the earth?

Lithosphere

Hydrosphere

Atmosphere 3. What are the effects of weathering?

The effects of weathering disintegrate and alter mineral and rocks near or at the earth's surface.

4. What is chemical weathering? Chemical weathering, involves changes in the chemical composition of rocks which results in their breaking up into smaller fragments or decomposition.

5. Mention the types of chemical weathering.

Oxidation

Carbonation

Hydration

Solution

D. Answer in Detail: 1. What are the different types of weathering? Explain any one type in detail. There are three types of weathering. They are:

Physical or Mechanical weathering

Chemical weathering

Biological weathering Mechanical or physical weathering: Involves the breakdown of rocks without any change in their chemical composition. It happens through direct contact with atmospheric conditions, such as heat, water, ice and pressure. Physical weathering is mainly brought about in the following ways:

Granular disintegration: when rocks become weak over a period of time due to alternate heating and cooling, and expansion and contraction, they disintegrate grain by grain.

Exfoliation: When the outer shell of rounded rocks or the surface layers of rocks become lose and feels off from the main rock, it is called exfoliation.

Block disintegration: when big block of rocks disintegrate from the main rock, along parallel joints or cracks due to expansion of the rocks during the daytime and contraction at night, it is known as block disintegration.

Frost shattering: In the temperate latitudes, the action of frost shatters rocks. Most of the rocks have cracks, joints or pore spaces and snow or rainwater usually collects in them. During the night, when the temperature falls, it results in the freezing of this water in the joints and pores. Since frozen water expands, it exerts pressure on the walls of the cracks. Hence, the cracks widen and deepen. This results the rocks to break up.

2. What are the effects of weathering? Explain briefly.

Mass Wasting: Weathering results into mass wasting. The downward movement of loose weathered material on hill slopes under the influence of gravity and lubrication by rain water or melted snow is called mass wasting.

Landslides: A landslide is the movement of rock, soil and vegetation down a slope.

Mudflows: Mudflows are also caused by wreathing, when the Earth’s surface is devoid of vegetation. It is a flow of water that contains large amounts of suspended particles and silt.

Soil formation: Soil is formed from the weathering of rocks and minerals.

3. What factors help in the formation of soil? The factors affecting soil formation are:-

Topography or relief relates to the shape and slope of the land, as well as the elevation and landscape. Topography slows or speeds up the rate of weathering by climatic forces s. soils vary with topography.

Temperature and rainfall are the two most important climatic factors which affect the rate of weathering.

Plants, animals and other organisms help create and enrich soil. The excrement from animals adds nutrients and matter to the soil.

Burrowing, invertebrates, such as earthworks, beetles, ants and termites, create pores in the soil through which air and water enter into the soil. The decomposed remains of plants and animals enriches the soil.

4. What does the term ‘soil horizon’ denote? What are the four main layers of soil? Soil is formed in several horizontal layers. These natural layers of soil are called soil horizons.

Top soil: this is the uppermost layer of the soil and is predominantly made up of organic material called humus. This layer is the darkest as it contains more organic matter. It is rich in minerals and is often the most fertile layer.

Sub soil: below the top soil, is a layer made up of finer rocks, silt and clay. This layer does not contain organic matter.

Weathered rock: Below the sub soil, is the layer of partly weathered rocks. This layer is the transition layer between soil and parent material.

Bedrock or parent rock: This layer is the bedrock. It is a solid unweathered layer of rock.

5. What are the two most common ways by which soil gets eroded? Explain briefly.

Sheet erosion: when there is heavy rainfall, the top layer of soil over a vast area gets washed away. It is known as sheet erosion.

Gully erosion: When rainwater in a region flows down the slopes making deep narrow furrows, it is called gully erosion. Such gullies make the land unfit for cultivation resulting in the formation of badlands.

6. What steps should be taken for the conservation of soil.

Afforestation: In this method, the soil cover is conserved by planting trees. Vegetation cover protects soil from wind and water erosion.

Controlling overgrazing: Overgrazing is the practice of grazing too many livestock on a land, for an excessively long period, such that the land is unable to recover its vegetation.

Crop rotation: Growing the same plant year after year removes minerals from the soil. To keep the soil fertile, these minerals must be returned to the soil. This is often done by crop rotation.

Planting shelter belts: Plants also prevent wind erosion. Shelter belts are thick rows of trees that obstruct the wind, thereby reducing its speed.

Fallowing: The field is left empty of crops for one or two years to give the soil a chance to regain the lost fertility and minerals. Land left uncultivated like this is called fallow.

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