Some Common Questions Based On Toposheets

Sourced from :- B R Hector
If you get these questions, look for these points in the toposheets and can write these answers:

1.Mention ay two features seen in the map extract which indicate the region has seasonal rainfall.Seasonal streams/ Broken ground/open scrub/seasonal tank/cart track motorable in dry season/narrow perennial channel in the dry bed of the river(after looking for these features, select any two features that you find on the topo sheet and write this way)

Ans: Open scrub and seasonal streams are two features in the map that indicate the region has seasonal rainfall. 
Rivers, steams and ponds/tanks are dry in nature.
Barren land shown in white colour also indicate tht the region has seasonal rainfall.
2.Mention any three features seen in the map extract which attract holiday makers.(look for various tourist destinations like temple, water falls, lakes, park, sunset points, etc and then write answers)

3. Which is the chief form of irrigation shown in the map extract? Give somE evidences to justify your answer.(look for perennial wells first, then the rivers, lakes, tanks, etc and give answer. For example, if you find the presence of many blue circles in the map, then you can write your answer this way.)
Ans: The chief form of irrigation is perennial well-irrigation. Presence of blue circles scattered all over the map .

4. Give one reason to explain why the steams in grid square ......... do not join a river.
(look for sandy soil , rainfall, etc)Ans; Reasons for streams not meeting the main river due to:-
* presence of sandy soil which is porous
* poor rainfall
* high rate of evaporation. (any two ) 
5. State two reasons for the absence of human habitation in some region of the map extract.( check for any features that is not suitable for human habitation – like dense forest, open shrubs, steep hills, deserts, lack of roads, etc)Ans: The region is densely forested, many streams with very steep hills. Expensive to build roads. 

6. What is the small white patch in the river?Ans: Barren island 

7. What will be the main occupation of the people be in i. highlands ii. Lowlands?i. highlands – collection of forest products
ii. Lowlands - agriculture

8. Why are there no metalled roads in the mapped area?( reasons may be many- look for dense jungles, or barren land, steep hills, or many streams – and then answer according to the features,)Ans: The area has dense jungles, steep hills and no important settlement- steams and barren land discourage the building of metalled roads.

9. Give evidence to prove poor rainfall in the region.
(look for features like sand dunes disappearing steams, scrub vegetation, broken grounds, etc. If you find these features, then you write the answer this way)Ans. The region has poor rainfall due to the
•Presence of sand dunes
•Presence of undefined and disappearing streams
•Presence of scrub vegetation
•Presence of broken grounds 
10. Give two reasons for the presence of only footpaths in the green wash.The reasons for the presence of foot-paths are:
* seep and rugged terrain makes construction of roads difficult.
* temples are the only destinations in the forested mountain region and hence foot-paths are created by the pilgrims.
* footpaths may be created by people who depend on forest produce. 

11. Why do so many contour lines so close together in the extract indicate about the topography?(look for steep hills, or a temple in the jungle and if u find these.................)Ans: Very steep (indicated by close contours) and hilly (indicated by many contours) land. 

12. How can we draw a climatic inference from a toposheet?

(there may be a question - what type of climate do you find in the particular area - look for these features and then write the answers accordingly -First of all, we should try to know which area of the toposheet belongs to. This gives us a faint idea about the part of the country and the type of climate prevailing there. Further, scanty amount of rainfall can be judged by seeing dry rivers, dry tanks, sand dunes and scrubs and scanty vegetation. Similarly dense forests indicate tropical monsoon climate.)

(If you find dry rivers, or dry tanks or sannd dunes, scrubs, scanty vegetation, then your answer wil be)

The area experiences scanty rainfall or poor rainfall with dry weather.

(if you find dense forests, then your answer will be)

The area experinces Tropical Monsoon climate.

Questions on occupation

13. What is the occupation of the people of a particular region from an extract of the survey map or toposheet?

(When you get a question on the occupation of the people , look for these features. Directly from a toposheet, we cannot know about the occupation of the residents. We can amplify the occupation by inferences provided on the toposheet. Therefore one must know the colours and what it indicates. For example, all of you know that yellow colour indicates agricultural land and hence agriculutre can be major occupation. Green colour shows forested or wooded area and this indicates that people follow in lumbering, furniture making, carpentry and bamboo work, etc. Presence of big towns, industrial area, railway station, etc., indicates that people must be employed in urban services. Rest houses in hilly areas show devp of tourism. symbols of mines, may suggest that some people are employed in mining activities. if you find grassy area, then it indicates sheep or cattle rearing. Settlement along roadside indicates devp of trade and commerce. If you locate wells, tanks, canals, etc., show the cultivation of cash or cereal crops. parks, lawns, historical monuments indicate occupations like tourism, recreation, cultural devp, etc. So, my dear students, when you get a question on the occupation of the people, look for these features and write the answer accordingly. for example if you find grassy area or open shrubs, then the occupation will be sheep and cattle rearing. I hope you got me. )

14. What occupations do the people follow in Highland areas?
Ans: High land regions with steep slopes have the following features: 

• most of the slopes are unsuitable for agriculture. Pastures on the slopes may be fit for grazing.
• forestry may be a predominant economic activity in this region.
• flat area over plateaus may be used for cultivation.

15. How can you judge the suitablity of land for agriculture from toposheets? give a good reason.

• a meandering river on the toposheet will indicate a lower or nil gradient. Thus, such a plain area would be suitable for cultivation.
• Dendritic or tree-like drainage pattern would confirm soft surface suitable for agriculure wheras trellised drainage pattern suggests chalk country, which is not much suited for cultivation.
• Sand features, e.g. barkhans and disappearing streams would indicate the dry conditions with the high temperature. These conditions are unsuitable for agriculture.
• presence of broken ground would confirm seasonal flooding. Silt deposition by rivers is a good sign for agriculture.
• network of canals, dams, tanks and tubewells will indicate intensive use of land for agriculture.
• so look for these features on the toposheet and write accordingly.

For example, which are the main occupations of the people in this area? give reasons in support of your answer.

( if you see yellow wash, perennial wells, green colour,kilns on the toposheet, your answer will be like this.)

Ans: Farming and forestry seem to be the two occupations in this area because a large part of the map has yellow wash which symbolizes cultivated area. A large number of perennial wells present in the area also support this inference. Some part of the map shows presence of open jungles.......(mention, south, or north, west or east) which is indicated by green colur which suggests forestry as an important occupation there. presence of kilns shows that lime and brick making is also an occpation of some people.



POINTS TO REMEMEBR REGARDING OCCUPATIONS:

• If you find KILN , then the occupation will be drying and baking bricks, pottery, limestone, etc. So you write the answer this way: The occupation is drying and baking bricks, pottery, etc due to the presence of Kiln in the area.
• if you find STONE QUARRY, then the occupation is quarring.
• If you find irrigation from wells, canals or tanks, farming is the occupation.
• if you find yellow wash, agriculture is the occupation of the area.
• if you dont find any source of irrigation, it means farming is likely to be dependent on rainfall only.
• mining is the occupation if you find settlements near mines or quarries.
• if you find settlements along the banks of the river, then fishing is an occupation of that area.
• if settlement is near the forest(green colour), then the people are dependent on forest products like fruits, nuts, or leaves. there may be primitive agriculture. so when you write the answer, write this way: people are dependent on forest produce or foresty and may practice primitive agriculure.
• if you find large settlements, esp near the metalled roads, the occupation can also be industries, trade, services.
• in case they are headquarters of districts, taluqs, employment can also be in administrative sector because of the presence of large number of offices and organisations.

so please go through the toposheet properly since one question will be definite on occupation.



16. What is the brown line in grid square ............. called? What does the figure written aong this line indicate?
(if it is a brown line , then it is a contour. Second part of the question - imagine you see figure 280 m ... then it means 280 m above sea level.)
Ans: The brown line that we find in grid square is Contour line. The line 280 m joins places 280 m above sea-level on the map.

17. What are the brown lines seen in such abundance? What do they indicate?
(same answer as question 16)
ans: They are contour lines. They indicate lines joining places having the same height above sea-level. Closeness of the contours indicates mountainous topography.

17. What is a causeway? Why are there so many causeways in the map?
Ans: Causeways are land raised across streams for use as metalled road or paths. The numerous streams crossing the metalled road are likely to flood them. 

18. Explain the term Depression in the map.

Ans: Depression is a shallow lowland in a sandy region often created by deflation of wind.

19. Name the geographical feature represented by white patches in the middle of the river.

Ans: The geographical feature in the middle of the river represented by white patches is an island or rocks or stores.

20. What do the following represent in the map? i. Black broken lines ii. Black curved lines.

i. Black broken lines indicate disappearing stream and black curved lines indicate broken ground.






21. Name 4 methods by which relief is shown on the map.* Contour lines * Layer Colouring/tinting * Spot height * Hill shading.

22. What is layer-tinting/colouring?
It is a method, where a colour scheme is used to show relief on the map.

23. What is cartography?

Cartography is an art and science of drawing maps, diagrams and charts.

POINTS TO REMEMBER:

RELATIVE HEIGHT OR APPROXIMATE HEIGHT: REMEMBER:-This height is not taken from the sea level but with respect to the surrounding area. It may be height of a dam, bridge, sand dune, or it can be depth of a well, tank, hill, or river canal, for example 2r, 3r, 5r, 6r, etc.

Example:

●3r the relative depth of the perennial lined well is 3 metres.(if 3r is written near the symbol of perennial well. don't write height but the depth)

5r the relative height of dry tank is 5 metres ( if 5r is written near the dry tank symbol)

16r therelative height of sand dune is 16 metres. (if 16r is written near the symbol of sand

dunes)

8r the relative height of river bank is 8 metres (if 8r is written near the river bank)

PLEASE NOTE: you must write the word RELATIVE HEIGHT/DEPTH of .................................

COLOURS:

7 COLOURS are used on toposheets:

i. BLACK: Names, lines of latitudes and longitudes, broken grounds, river banks, dry rivers, surveyed trees, heights and their numbering, railway mines, telephone, telepgraph lines

ii. RED: Grid lines (eastings and northings) , their numbering, roads, cart tracks, settlements, huts and other buildings.

iii. GREEN: Forested and wooded areas, scrubs, scattered trees, orchards

iv. BLUE: Water bodies containing water like wells, rivers, etc

v. YELLOW: cultivated areas

vi. BROWN: Contour lines, their numbering, form lines, all sand features like sand dunes, sand hills, stony waste

vii. WHITE PATCHES: uncultivated and barren lands

DIRECTIONS

Directions are important for physical as well as urban features. the physical features involve the directions of rivers, streams, and the urban cities from one another.

When a question is asked regarding the banks of the river or direction of the river, the following steps should be observed.

• first of all, look at the spot heights to determine the slope of the land. As you know, spot heighs are marked this way ●265 ●289
• see which spot heights are higher and where it is lower, and then you will know which way or direction it slopes. the slope of the land may be from north east to south west. and if you see a river , then it flows from north-east to south-west.
• to know on which side or bank of the river a place is situated (a place may be a temple, settlement, town, etc)one has to locate the source of the river. Having located the direction of the river, imagine yourself standing at the source of the river f acing the main river. to your right is right bank and to your left is left bank. SO SIMPLE, BOSS!!!

when a question is askend on directions with reference to urban cites/settlements, remember these points.

• some times the questions are asked on the direction of a city or settlement with a reference to the other. First of all, pay attention to the words 'FROM' a place and 'TO' a place. Imagine yourself standing on the 'FROM' PLACE and look at the TO PLACE. Use the direction arrow and write the direction.

FEW IMPORTANT TERMS:


A. Layer Tinting: Layer tinting is a method of showing relief by color. A different color is used for each band of elevation. Each shade of color, or band, represents a definite elevation range. A legend is printed on the map margin to indicate the elevation range represented by each color. However, this method does not allow the map user to determine the exact elevation of a specific point—only the range.

b. Form Lines. Form lines are not measured from any datum plane. Form lines have no standard elevation and give only a general idea of relief. Form lines are represented on a map as dashed lines and are never labeled with representative elevations.

c. Shaded Relief. Relief shading indicates relief by a shadow effect achieved by tone and color that results in the darkening of one side of terrain features, such as hills and ridges. The darker the shading, the steeper the slope. Shaded relief is sometimes used in conjunction with contour lines to emphasize these features.


d. Hachures. Hachures are short, broken lines used to show relief. Hachures are sometimes used with contour lines. They do not represent exact elevations, but are mainly used to show large, rocky outcrop areas. Hachures are used extensively on small-scale maps to show mountain ranges, plateaus, and mountain peaks.


e. Contour Lines. Contour lines are the most common method of showing relief and elevation on a standard topographic map. A contour line represents an imaginary line on the ground, above or below sea level. All points on the contour line are at the same elevation. The elevation represented by contour lines is the vertical distance above or below sea level.

(1) Index. Starting at zero elevation or mean sea level, every fifth contour line is a heavier line. These are known as index contour lines. Normally, each index contour line is numbered at some point. This number is the elevation of that line.
(2) Intermediate. The contour lines falling between the index contour lines are called intermediate contour lines. These lines are finer and do not have their elevations given. There are normally four intermediate contour lines between index contour lines.
(3) Supplementary. These contour lines resemble dashes. They show changes in elevation of at least one-half the contour interval. These lines are normally found where there is very little change in elevation, such as on fairly level terrain.

Interpreting Toposheets -2

Let us look at this toposheet. Double click on this toposheet. You will see the enlarged topomap. Let us look at the Northern part of the toposheeet- see various features. Can you see QC,- What is it?

According to the international system of location of a place the whole world has been divided into various squares. It starts frm the place where the equator and prime meridian meet and is named UA. Under the same fashion the whole world has been divided.......................... Thus the square is named QC.
QC means that there is end of numbering of northing or easting i.e 0-99 on a toposheet it is written after every 100km. Here it is the end of northings.

Look at the town Panthawada- It has a police station (PS), Post Office (PO), well connected roads. a temple, perennial wells, etc.

Now let us to to the north-east of the map. What do you see over there? -
OPEN SCRUB- What does it mean? It indicates desert or semidesert condition. The occupation in this area would be sheep or goat rearing.
You will also see Lime Kiln- It is a furnace for baking limestone.Its presence shows the trade possibilities and the people working in it.

Let us study 6 figure grid reference. Look at the triangulated height of 224. Let us first find out four figure grid reference. Let us see the eastings first. We locate it in easting 82. Let us see the northings. It is in northing 94. So four figure grid reference of the triangulated height is 8294. Now how do you find four figure grid refernce. We have already found out the four figure grid refernce. (8294) Let us divide that square (8294) into 10 equal squares as it is I have done in the toposheet. Look at it closely. For every 2 cms, you mark one square. So you will have 10 equal squares. For 6 figure grid reference, first 3 figures are of eastings and the second part of the 6 figure reference is of northings. We have already know easting is 82. Let us now find out the third figure from those small squares. Its in first square. So first three figures are 821 and the second part is 941. So six figure grid reference is 821941 or 822941. Did you get it? I hope so anyway.

Can you see the broken ground? (I have marked in the toposheet) What is a broken ground? They are generally found along the banks of a river. Broken ground is caused by erosion during rain when the river is in flood. It usually happens in the area devoid of vegetation.

Interpreting Toposheets

Hello,

See the features of this toposheet. Divide the toposheet into 4 quarters. Study the each quarter. For example North west corner (A), North East Corner (B), South West Corner(c) and South East Corner (D). For example what features do you see in the A Corner???First of all, you see river Sipu, a few nucleated settlements, yellow wash, open scrub, little bit of green forest on top of A corner, we can see some spot heights too. Can you see a cart track (red line)? We can also see perennial wells (blue). Did you spot stony waste (8596)? In the same way, go through the B corner and C corner and D corner. Make a mental picture of the toposheet with prominent symbols. After having a quick glance of thetoposheet, read the questions that are asked. You have 15 minutes to read the question paper. First read the other questions and then come to the toposheet which requires more time to read. Keep a pencil ready to mark few features.For the bigger view of the toposheet, click on top of the picture.

• Can you see R.F.? You can see at the bottom right. R.F. is 1:50,000. I have already explained to you how to write R.F. in the earlier lesson.
• can you see the scale? You can see almost near the R.F. The scale is 2cm to 1 km. It means 2cm on the map is equal to the 1km on the ground. Good, i suppose u understood.
• What's the contour interval of the toposheet? Check the contour interval near the scale. Contour interval of this toposheet is 20 metres.(usually it is 20 metres)
• What else can you see? Ok, let's do the direction which i have explained to you earlier. Find out what is the directionof Rajkot lie from Gangudra? First of all, Rajkot is in grid square 8995 and gangudra is in grid square 8793. Imagine you are in Gangudra and you want to go to Rajkot from Gangudra? First of all, you hv to go up which is north and then you have to turn right, which is east direction.Therefore the comapass direction is north-east from Gangudra. Do you follow?
• Where do you find the lowest part in the toposheet? The south west corner is the lowest part in the map. because two rivers flow towards south west whichis an indication of the slope. check the spot heights in the map. they are decreasing towards south west. Identify some spotheights in the map.
• See the settlements on the map: What type of settlement do you find? Ofcourse, nuclear/compact/clustered. If you didnt understand, read the text book on settlements and come back to the blog.
• What kind of rainfal this area gets? check the rivers-we can see broad sandy bed exposed, a thin water channel, (in blue) several cart tracks, and a pack track. This shows that the area gets seasonal rainfall.
• Now let us see the occupation. Study the toposheet closely. I had told you about the occupations. Go through it again. Let us study the occupation of Bhadli (Jhat) - grid square 8596. What do you notice there? click the toposheet and check. its is A CORNER. There is a river, perennial wells (Blue dots), yellow patch(which means agriculture) and stony waste. Can you see them? From this we know that the occupation of the people of that area is cultivation and stone cutting or extraction of limestone. This is indicated by the presence of agricultural land ( in yellow colour), perennial wells and the presence of lime kilns.
• It is a clustered settlement too.
• Can you see the irrigation facilities or source of water? We can see the river which has narrow blue line which means it is perennial even though the river is seasonal. Then we also can see the perennial wells. So two perennial source of water is the River waters and well irrigation.
• Let's study man made features - we can see few temples in the toposheets and permanent huts. I couldn't see any post office. As I have told you, my eyes are not very sharp. In the exam, they will ask one or two man-made features. So the man-made features are temples and permanent huts.
• Now let's study the natural features - We can see rivers, trees, islands in the middle of the river, jungles, mines, pack tracks, cart tracks, lined wells, etc. You can see all these in this map. So, you select any two. The natural feature is river and forest. Sometime they will give a grid square and ask to you to mention one man-made feature and one natural feature. Go and locate that grid square and follow the points that I have told you.
• Let us see the drainage pattern on the map. See the area around the town Gangudra.(Grid square 8793) See the drainage pattern around the area-dont see only in the grid square 8793. Go beyond that. The river or drainage pattern is Rectangular or Trellised. Can you see the shape of the river? Thin lines that join the main river. Read the text book regarding the drainage pattern (if you have not understood) There are three drainage patterns - Dendritic(Tree like or veins of a leaf) Trellis/Rectangle and Radial.
• Let us study the river bed of Sipu- In what two ways does the river bed of Sipu convey that it flows through a region of seasonal rainfall? We did go through that earlier. Study the river. It has a broad sandy riverbed which is exposed. If you dont understand the sandy river bed, go to the text book and looks for the symbos of sandy bed. You will see it in my blog too. It also has a thin water channel in the middle of the river. We also see many cart and pack tracks passing the river. Therefore, the river doesn't have much water in the summer season and so the river dries up. Do you follow me? Since the river is dry, you see the sandy beds and cart and pack tracks passing the river. So the people can cross the river during summer. Therefore it is a seasonal river.(it means the river gets water only in the rainy season).
• What are the conventional sighs near north east part of the toposheet near open mixed jungle? - check corner B - We find broken ground there. So what is broken land? Broken land gives rise to Bad land topography. These are generally found along the banks of a river. Broken ground is caused due to erosion during rain when the river is in flood. It usually heappens in the area where there is no vegetation/plants.
• Some time a question comes on the comparision of two settlements. Now let us study the village Jigol (grid square 8590) and other villages. Jigol is better off than other settlements. It has good transport system in comparision with other villages. We can see many cart tracks leading into the village. Plus it has many lined wells for irrigation purposes.
• In which quarter of the map extract do you find the lowest area to be? Divide the whole toposheet into 4 corners. We have done that in the beginning. Look for the spot heights in the toposheet. if you study the heights, you will find south west qurater of the map are decreasing towards the south west. See also the river flowing. They flow towards the south west. So the south-west corner of the map exatract is the lowest region.
• Hope you know how to find grid squares - 4 figure or 6 figure/digit grid reference. Find four digit grid square is easy but the problem begins when you have to find 6-digit grid reference. When you are asked to locate the 6-digit reference, rememeber these points. First find the square. Ok, let us locate a place using 6-figure grid reference of a temple in the north east of Odhava. Ok, let us see the 4-figure grid reference. It is in the grid square 8992. This is four figure grid reference. now we need 6-figure grid reference. After locating 4-figure grid reference, divide that square into 4 equal parts. First take a ruler and place it on the horizontal line of that grid square(. get the mid point. Then place the ruler on the vertical line and find the mid point and join these mid points. then u get the mid point of easting and northings. then u locate the spot in the grid square and if the spot is beoynd the mid point, then it wil be above 5. You can find the exact 6 figure grid reference by dividing grid squares into 10 blocks. Hold the scale vertical and horizontal on that grid square and join them. Now u get 10 X 10 equal squares. NOw you see where is the spot and give the grid reference.894925

Revision -Important Toposheet definitions

IMPORTANT DEFINITIONS
DEFINITIONS FROM TOPO MAPS

REPRESENTATIVE FRACTION (RF): It is the ratio between the distances on the map to its corresponding distance on actual ground. The RF on this map is 1:50,000. 

2. SCALE : Scale is the ratio between the distance of any two points on the map and the actual distance of the same points on the ground.

The scale of the given map extract is 2 cm: 1 km or 1:50,000.

3. CONTOUR: Contours are imaginary lines drawn on maps, joining all places with the same height above sea level. 

4. CONTOUR INTERVAL: The interval between two consecutive contours is called contour interval (*it is a constant 20 mts in your toposheets.) 

5. INDEX CONTOUR: Contour lines are thickened at regular intervals to make it easier to read contours. For example at every 100 mts the contour line is made darker. The darker lines are called Index Contours. 

6. TRIANGULATED HEIGHT: It is the height of a place which has been calculated using trigonometry, represented by a small triangle e.g. - 540 

7. SPOT HEIGHT: The height of random places between contours shown with a dot. Eg - .425 

8. BENCH MARK - Height of a place actually marked on a stone pillar, rock or shown on a building as a permanent reference. It is written as BM 200 m. 

9. RELATIVE HEIGHT: Relative height is the height of a feature with reference to the height of the surrounding land and NOT to sea level.
It is represented by the height with a small ‘r’ eg –12r. 

10. ROCK OUTCROP: It is a portion of rock jutting above the surface of the earth. 

11. SHEET ROCK: Large areas of rock where the overlying soil layers have been eroded and removed due to mechanical weathering. 

9 STONY WASTE : A large area usually in arid/semi arid regions where the finer sand/soil has blown away leaving a surface covered with boulders, stones and pebbles. 

10. BROKEN GROUND: A relief feature found mostly in dry regions around rivers and streams. It is land around river, which is totally
weathered (exfoliated) due to alternate cooling and heating. 

11. FIRELINE: A cleared pathway in a forest to prevent the spread of forest fires.

12. MIXED FOREST: A forest with more than two varieties of trees growing in close proximity to each other. 

13. OPEN JUNGLE: A forest where trees are widely scattered. 

14. DENSE JUNGLE. : A forest where trees grow very close to each other. 

15. OPEN SCRUB: Scrub is a vegetation found in regions with less than
100 cms of rainfall. Therefore it indicates a dry region. 

16. BRACKISH: It is a well, which has water with very high salt content – generally unfit for drinking purposes. 

17. CAUSEWAY: It is a raised road over a small water body. (Usually a road used only in the non rainy months.} 

18. CUTTING: A portion of land, which has been cut in order to make land available for transport routes. (it is indicative of a rocky region) 

19. EMBANKMENT: They are raised rock or soil filled constructions on which roads/railway tracks are built. Also made near tanks and rivers to prevent flooding.

20. FORM LINES: Form lines are contour lines, but show only approximate heights above sea level as they are used to indicate the elevations of the area which are not accessible for proper survey. Hence they are drawn as broken lines and are called 'form lines'.

21. Q.C. Q.D., OC, OD,PQ, ETC : These are alphabetical codes used to represent the biggest grid sq. of 10,000 square kms.

The Govt of India has adopted metric system for all measurements. All the ordnace survey maps issued by the Survey of India were drawn to the scale 2 cm = 1 km. In this system , the surveyed territory is divided into 100km X 100 km squares, and each square is denoted by English alphabets. for example, OC, OD, PQ, PG, etc . This system of map drawing is known as National Grid Reference.

22. LAYER TINTING: (colouring)
While spot heights show the height of the land, they only do so at certain points. To provide an overall image which conveyed height, a technique called layer tinting was developed. Layer tinting uses different colours (or shades) to represent different heights. It is a mapping convention for darker colours to signify greater height. When using layer tinting, green is often used for low land, yellow for higher land and brown for the highest land.
Layer tinting is most commonly found on physical maps. While layer tinting is useful, it does not show the detailed shape of the land.

23. DEP: It is a depression often found in sandy areas where the wind, having blown away the sand, leaves a hollow or a depression.

24. HACHURING: Early cartographers attempted to show surface features on maps by using the technique of hachuring. Hachures use short lines of varying thickness to show the shape and slope of the land. In accordance with this technique, the steeper the slope is, the thicker the lines are which represent it. While hachuring was initially innovative for its time, it gradually began to be replaced since the actual height of the land was not depicted.

25. LIME KILN OR BRICK KILN: These are open furnaces where limestone is purified or bricks are baked for construction purpose.

26. HILL SHADING: Hill shading resembles a light and shadow effect. Valleys and the sides of mountains appear as though they are cast in shadow. This is a visually striking method, which is ideal for providing an overall view of the relief of an area. Hill shading, however, does not show height which means that it is no more accurate than hachuring.

LEARN THEM BY HEART - ALL THE BEST !!!

Cell Organelles: Their Structure and Functions

We know that the cell is the basic structural and functional unit of life. But what is present inside a cell? How does it perform its various functions?

A cell contains various cell organelles which help perform its functions. Let us explore what all cell organelles are present inside the cell

Some organelles are visible under the light microscope while some are visible only under the electron microscope.

Now let us study about the organelles that are visible under the light microscope

Cell Membrane

Take a peel of onion by separating it from the fleshy portion. Add a drop of methylene blue on a slide containing the peel, put cover slips, and observe it under a microscope. What do you observe? Note your observations and draw a diagram of the structure you have observed.

You will observe brick-like cells placed one over the other with a round ball like nucleus in the centre. The boundary of the onion cells is known as the cell membrane, and it is covered by another thick layer called the cell wall.

Hence, thecell membrane is the outer boundary of the cell, which separates one cell from the other. It also separates the contents of the cell from its surrounding medium.

The cell membrane is porous in nature and helps in the inward and outward movement of substances.

Cell Wall

The cell wall is an additional protective, rigid structure present outside the cell membrane. It is present only in plant cells. It protects them from heat, humidity, pressure etc.

Cytoplasm

The jelly-like substance present between the cell membrane and the nucleus is called the cytoplasm. It is an important component of the cell as various cell organelles like mitochondria; ribosomes etc. are present in it.

Nucleus

The nucleus is a spherical structure which is generally present in the centre of the cell. Let us study the components of nucleus.

The cell membrane, the cytoplasm, and the nucleus form the basic components of the cell.

Do You Know? Do you know that the red blood cells of the human body do not have a nucleus? Paramecium is a unicellular organism having two nuclei. Some muscle cells in humans have a large number of nuclei.

Vacuole

When you observe an onion peel under the microscope, you will observe a large empty space in the cells. Do you know what these spaces are?These empty spaces are called vacuoles. These vacuoles are larger in plant cells than in animal cells.

The organelles visible under an electron microscope are

Endoplasmic Reticulum

Endoplasmic reticulum, or ER, is an interconnected network of membranous structureslike tubules, vesicles, and cisternae. Cisternae are the flattened disk-like membranous structures. Tubules are tubular in shape, while vesicles are sac-like structures. The function of the ER is intra-cellular transport

Golgi Apparatus

They are the membrane-bound, sac-like structures called cisternae. They are arranged parallel to each other in stacks. They were discovered by Camillo Golgi in 1898. Golgi body is usually composed of five-eight cisternae in stacks. Vesicles leave the Golgi body from one end known as the cis face. The other end is known as the trans face. The table given below lists some functions of the Golgi apparatus.

Mitochondrion

Mitochondrionis a membrane-enclosed organelle found in eukaryotic cells.

Mitochondria are responsible for the production of most of the energy (or ATP) in cells. Therefore, mitochondria are also known as the power house of cells. A mitochondrion is composed of two lipid membranes, enclosing the matrix. The inner membrane gets folded to form numerouscristae. Cristae are the main site for ATP production. Mitochondrial matrix contains mitochondrial DNA and ribosomes.

Lysosomes

They are the membrane-bound vesicles, which contain digestive (hydrolytic) enzymes like acid hydrolase. They digest a variety of substances including worn out organelles, food particles, viruses, and bacteria. They are also known as ‘suicide-bags’ of cells as they burst out and release hydrolytic enzymes in the cytosol, where cells are heavily injured.

Plastids

Plastids are major organelles found in plant cells and algae

Chloroplasts are plastids containing the pigment called chlorophyll. A chloroplast is enclosed by two lipid membranes.

Ribosomes

They are found either freely floating in the cytoplasm or attached to the outer surface of the endoplasmic reticulum. They help in protein synthesis.

Observation of Plant and Animal Cell

Let us perform an experiment to understand how does a cell look like under microscope?

Take an onion and cut it into two halves. Peel off a transparent piece of skin from the inner layer of onion with the help of a forceps. Place this transparent skin on a slide and add a drop of iodine solution to it. Carefully place the cover slip on the slide. Wipe off the excess amount of iodine solution from the slide with the help of tissue paper. Observe the slide under microscope. Carefully have a look on the shape of onion cell.

Experimental set up

Observation:

You can see several rectangular cells, each with a small, spherical nucleus in it. These are called epidermal cells that are found on the surface of the plant body.

Onion cells

Cells are basic unit of life that is capable of doing all the required biochemical processes that a normal cell requires to do in order to live. The basic need for the survival of all living organism are same. All living organisms need to digest food (to obtain energy), respire and to get rid of metabolic wastes. Who does all these functions of the body?

It is the cell that carries all these metabolic function in body. Hence, cell are called functional unit of life.

Observing Animal Cell

Take a cotton bud and gently rub it along inside of your cheek. Smear the cotton bud onto a slide. Add a drop of methylene blue on to the smear. Carefully place a covers slip on top of the slide. Now observe the slide under microscope.

(Note: Methylene blue is a dye used to stain and view animal cells)

Experimental set up

Observation

You can see several polygonal cells lying here and there on slide. This represents the structure of animal cell.

Differences between Plant and Animal Cell

Animal cell	Plant cell
Generally small in size	Usually larger than animal cells
Cell wall is absent	Cell wall is present
Plastids are absent	Plastids are present
Vacuoles are more in number and smaller in size	Vacuole is single and larger in size
Single, highly complex, and prominent Golgi apparatus is present	Many simpler units of Golgi apparatus, called dictyosomes, are present