Author Archives: Raghvendraschool

As we all know, Earth is the only planet in our solar system that has the viable conditions for life to exist. While the presence of water and oxygen is the main reason, we must also recognize that life would not have been possible if it weren’t for the oxygen-emitting plants, life would not have been able to take shape on Earth. These plants are not only our source of oxygen but also the major source of the food that we eat.

Herbs, Shrubs and Trees

We can classify plants on the basis of the thickness of their stems and the place of origin of their branches, into three broad categories:

Herb: These are plants that have green and frail stems. Usually, these are small plants with not many branches.

Some common examples of herbs are Basil, Coriander, Mint, Oregano, Thyme, Parsley, Rosemary etc.

Herbs: Small plants with tender stems

Common herb examples

Shrubs: These are plants with hard but not exactly thick stems. Their branches generally originate from the base of their stems. These are much taller than herbs but usually shorter than trees.

Some common examples of shrubs are Aloe Vera, Rose plant, Jasmine plant, Blackberry plant etc.

Common shrub examples

Trees: These are plants which are very tall and have a thick and hard stem. The branches originate from the upper part of the tree and are very high above the ground.

Some common examples of trees are neem, peepal, coconut tree, mango tree etc.

Some common examples of trees

There are two other kinds of plants which are:

Creepers: These are plants which have soft, weak and green stems and hence cannot stand straight and instead spread on the ground.

Some common examples are sweet potato, watermelon, pumpkin etc.

Some common examples of creepers

Climbers: These are also plants with soft and weak stems but instead of spreading on the ground they take support with a nearby object to climb up.

Some common examples of creepers are cucumber, bean, grapevine, money-plant etc.

Some common examples of climbers

Let us observe and study each part of a plant step by step:

Stem

Growth cycle of a common stem

The Stem is the part of a plant which is responsible for supplying water to all parts of the plant. It is the stem which bears branches, flowers, leaves, fruits and buds. The root sucks the water and minerals from the soil and it is the stem’s function to push this water upward to other parts of the plant.

We can observe this by soaking the stem of a plant in a glass with water. On adding coloured ink to the water, we observe that after a while the stem and leaves of the plant start to turn the colour of the ink, which is proof that the stem carries the water to the different parts of the plant.

The experiment helps demonstrate how stems are responsible for carrying water to different plant parts

Leaf

The leaves of plants are majorly responsible for performing two essential functions for the plant’s survival and growth. These two functions are called transpiration and photosynthesis.

Transpiration: Transpiration is the process through which plants release the excess amount of water in the air. When the water travels via the stem to the leaves, some of it gets used up to prepare food, while the excess water is converted to water vapour due to the presence of the sun. Transpiration is important for the plants as it helps the plants to cool down. In the absence of transpiration, the temperature of the leaf becomes unregulated which may lead to the eventual death of the plant.

We can observe transpiration by enclosing a leafy part of a plant in a closed polythene bag and keeping it in the sun. After a while, we see tiny droplets of water on the inside of polythene bags, which are proof that the leaves have performed transpiration.

The process of transpiration

Photosynthesis: Photosynthesis is defined as the process that helps leaves prepare food for the plant with the help of carbon dioxide and water. Photosynthesis occurs in the presence of sun and is aided by the presence of a green pigment in leaves called chlorophyll. Plants also release oxygen in the process. The food prepared is stored in various parts of the plant. In absence of photosynthesis, the plant is unable to utilise the water and minerals to prepare food for its nourishment and gradually dies.

In order to see if leaves really do perform photosynthesis, we take a leaf and immerse it in a test tube filled with spirit. Placing this test tube in a beaker filled with water, we heat the beaker. After the leaf loses its color, we wash it and pour iodine solution on it, as can be seen below, which shows the presence of starch thus disproving our doubts.

Parts of a Leaf

Petiole: This is the stalk via which the leaf is joined to the plant.

Lamina: This is the expanded part or the green portion of any leaf which is responsible for photosynthesis.

Veins: The many lines that run through the surface of the leaf are called veins and the design made by them is called leaf venation. They transport water and minerals.

Midrib: This is the central, prominent thick structure right in the middle of the leaf that helps support the leaf and prevent it from breaking.

A labelled diagram of a leaf

We distinguish between two major types of leaf venation.

Reticulate venation is said to exist when the veins form a net-like shape on either side of the midrib. This type of venation is seen to exist in dicots like guava and mango.

Parallel venation is said to exist when the veins run parallel to one another. This type of venation is seen to exist in monocots like banana, wheat, coconut etc.

Parallel and reticulate venation

Root

The root is a very important component of the plant system, as, without the presence of roots the plant ceases to exist. This is because the roots perform three major functions essential to the growth and survival of the plant which are:

• Roots are responsible for absorbing minerals and water from the soil and transferring them to the stem. It’s only after root has transported water and minerals to stem that the stem becomes capable of transporting these to all parts of the plant.
• Another important function of roots is to firmly anchor the plant in the ground. This is essential to support the upright position of the plants.
• Roots also perform the function of storing important nutrients and food for growth.

There are two major types of roots that exist in plants and these are:

Tap Roots	Fibrous Roots
1. In this type of root system, there is one prominent and long root and a bunch of smaller roots that grow from this main root called lateral roots.	1. In this type of root system, a group of similar sized roots emerge from the base of the plant. They do not have a main root.
2. It is hard to pull out plants with tap roots as these go deep within the soil.	2. These plants are relatively easier to pull out as the roots don’t go very deep in the soil.
3. This root system is seen to exist in plants with leaves displaying reticulate venation.	3. This root system is seen to exist in plants with leaves displaying parallel venation
4. Examples of plants with tap roots: carrots, turnip, gram, gram, China rose etc.	4. Examples of plants with fibrous roots: banana, wheat, maize, onion, bamboo etc.

Flower

The flowers are the colourful, seed-bearing parts of the plant that grows at the end of the stem. A typical flower exhibits the following structure:

Petals: These are bright, colourful and broad parts of the flower. Taken together, the petals of the flower form what is called a Corolla.

Sepal: This is the green, leaf-like structure of the flower that encloses the petals and is responsible for protecting the flower when it is in its bud form and supporting it when it is in its bloom stage.

Stamen: These are the long and slender parts of the flower that become visible upon removing the petals and sepal of a flower. Typically, a stamen consists of an anther i.e. the head of the stamen and a filament i.e. the long cream-colored stick. The stamen is also known as the male reproductive part of the plant.

Pistil: This is the innermost part of the flower, typically consisting of a stigma i.e. the head of the pistil, a style, which is the long sticky part that attaches the stigma to the ovary i.e. the small and swollen sphere at the base of the pistil. Pistil is the female reproductive part of any flower. The ovary contains small bead-like structures which are called ovules.

The structure of a flower

Stamen	Pistil	Ovary

Important Definitions

Stomata: These are the small microscopic pores present on the leaf through which exchange of gases and transpiration takes place.

Annuals: These are plants like wheat and maize that complete their life cycle in one season and then die. They are usually herbs.

Biennials: These are plants like carrots and radishes that complete their life cycle in two seasons.

Perennials: These are plants guava and palm that continue their life cycle for more than two seasons, i.e. they manage to re-grow every spring.

Aerial roots: These are roots of plants and trees that grow above the ground instead of under the ground as shown in the image below.

Aerial Roots

Everything around us is undergoing a process of change. Our hair and nails keep growing. Leaves die and new leaves take their place. While some changes in our environment are temporary and can change back to their original positions, other changes are relatively permanent.

On this basis, changes around us can be classified into two broad categories:

1. Reversible changes
2. Irreversible changes

Reversible changes can be described as changes that can be reversed by reversing the action or changing the conditions. Example: freezing of water, rolling of a chapati from dough etc.

Irreversible changes can be described as changes that cannot be reversed even after bringing about changes in the conditions. Example: rusting of iron, cooking of vegetables etc.

Figure 1 Closing and opening of mimosa leaves represent a reversible change

Figure 2 Cooking of an egg into an omelette represents an irreversible change

Substances and materials usually undergo two major types of changes:

• Physical change: This represents a change not in the chemical identity but the physical form of a substance. When substances undergo a physical change, there is no formation of a new substance and more or less these changes can be reversed. Example: boiling of water and melting of ice represent reversible physical changes while growing of height is an irreversible physical change.

Figure 3 Physical Change

• Chemical change: This represents a change in the chemical identity of a substance. These are irreversible changes because the original substance gets converted into a new substance and cannot be brought back. Example: cooking of rice, burning of matchstick etc.

Figure 4 Chemical Change

Difference between physical and chemical changes:

Physical Change	Chemical Change
A change in matter which occurs without causing any change in the composition of the matter is known as physical change	While a chemical change is defined as the change in the chemical composition of matter
Usually, physical changes are reversible in nature	While chemical changes are often irreversible
No new products are formed when an object undergoes physical change	Chemical changes often lead to formation of new products
These changes have no impact on the molecular composition of the substance	Chemical changes have a direct impact on the chemical bonds and molecular composition of a substance
A few changes occur when cooling or heating is done	These changes involve absorption or release of energy

There are other ways to bring about changes in substances:

• Mixing two substances together: A small amount of curd is added to warm milk which leads to conversion of that milk into curd. This is an irreversible change.

When we add a salt to water it becomes salty but this is a reversible change.

• Expansion and Contraction: In order to make tools like an axe, the ring of its iron blade is heated which allows it to expand i.e. become larger in size and then is allowed to cool down which makes it contract again i.e. become smaller in size leading to a tight fit of the handle.

Figure 5 Curd is added to milk to allow it to set into curd

On a day-to-day basis, we are faced with various instances when we are required to separate substances from one another. Whether it is picking out chillies from our paranthas/poha or separating tea leaves from tea while serving it, the need for separation of substances is something we encounter on a daily basis. It is usually because of one or all three of the following reasons:

• To separate two dissimilar but useful elements like in the case of butter and milk. Milk is churned in order to obtain butter.
• To segregate useless elements from the useful ones like in the case of separating tea leaves from tea.
• To remove and discard impurities or potentially harmful substances like picking out small pieces of stones and other impurities from rice and wheat.

Figure 1 Separating tea leaves from tea

Problems arise when the materials to be separated are really small in size or differ in their composition. It is nearly impossible to separate grains of salt from grains of sand by hand or trying to separate oil from water. We might need to use methods other than simple handpicking even though for a lot of separation processes, even handpicking might be enough.

Methods of Separation

Figure 2 Methods of Separation

• Handpicking: The simple process of separating slightly bigger sized harmful substances or other useful substances or impurities like small pieces of stones, husk and dirt from grains of wheat, pulses and rice is called handpicking. In situations when the quantity of such impurities is not very large, handpicking turns out to be a time-saving and convenient procedure of separating substances.

Figure 3 A group of individuals separating two types of grains

• Threshing: After the crop is harvested, stalks are left to dry under the sun. A single stalk has some 100 pieces of grain seeds joined to it. It is manually impossible to pluck each grain seed which is very small in size from the stalk and hence handpicking as a method of separation does not work here. That is why we use a method called threshing to separate these grain seeds.
  • Thus, Threshing can be defined as the process of separating the edible part i.e. grain seeds from the stalk by either with the help of machines, bullocks or sometimes by beating them.

Figure 4 a) Threshing by hand b) Threshing by machine

• Winnowing: Even when threshing is done, husk or chaff is still attached to the grain seed and since the size of the two is quite similar, handpicking does not work and neither does threshing. Hence, a method called winnowing can be used.
  • Winnowing can be defined as the method of separating lighter husk particles and heavier grain seed components by blowing a current of air through them. The lighter husk particles are carried away by the wind and the grain seeds get separated. This husk can be further used as fodder for the cattle.

Figure 5 Process of winnowing

• Sieving: Sometimes even after the grain seeds have passed through the stages of threshing and winnowing, husk may still be attached to the grain or it may have collected stones and dirt in the earlier stages which need to be removed and this separation is usually done with the help of a sieve.
  • Sieving is a very simple, convenient and time-saving process through which particles of varying sizes can be separated from each other with the help of a sieve. A sieve is nothing but a simple device with small pores in it which allow finer materials like flour to pass through leaving behind any impurities it might contain.

Figure 6 Sieving

• Sedimentation, Decantation and Filtration
  1. Sedimentation: Sedimentation can be defined as the process through which dirt and other heavier particles in a mixture settle at the bottom of the vessel when water is added to it. When the dust and dirt particles have settled, the clear water which forms the upper layer is moved to a different container and the dirt and dust is done away with. This technique can also be used to separate two liquids which do not mix with each other (also called immiscible liquids) and is called decantation.
  2. Decantation: Decantation can be defined as a technique through which immiscible liquids or a liquid and a solid substance are separated. For example, take the case of oil and water. These are two examples of immiscible liquids. Once we pour oil in water, oil forms the upper layer of water and can be easily separated by gently pouring the mixture in another container till all the oil has been removed. Sometimes smaller dirt particles get carried along with the water in the process of decantation which needs to be further removed. This can be achieved through the process of filtration.
  3. Filtration: Filtration is the process through which smaller particles like dirt etc. are separated from a solution by making the solution pass through a medium (often a filter paper). This medium is such that only liquids are able to pass through it because of the presence of very tiny pores in it. The filter paper is molded to form a cone and this cone-like structure is then affixed to a funnel through which the dirty solution is allowed to pass. Sometimes, filtration can also be applied to separate pulp and seeds from the juice. It can also be used to separate cottage cheese or paneer from milk.

Figure 7 Sedimentation, Decantation and Filtration

• Evaporation: Evaporation is the process of converting liquid into gas or vapour by increasing the temperature or pressure of the liquid. This process is often used to separate salt from salt water or salty sea water. Sea water has a number of salts present in it. Shallow pits called evaporation ponds are constructed and salt water is allowed to stand in these. After some time, the water gets evaporated, leaving behind the salts. Common salt is separated from this mixture upon further purification.

Figure 8 Salt Evaporation Ponds

Use of more than one method of separation

Often, we are faced with mixtures and solutions that cannot be separated by use of a single separation technique. A number of such techniques need to be applied simultaneously to achieve the desired result.

Take for example the case of a salt and sand mixture. We know handpicking will not work and considering both of them weigh just about the same, neither will winnowing.

And hence we try to separate the two with the help of filtration or decantation.

We take a beaker and add water to the said mixture of salt and sand. While the salt dissolves in water, the sand deposits at the bottom of the beaker and can be separated from the salt solution with the help of a filter paper or by gently pouring the salt solution in another container. We now have to separate the salt from water, for which we will simultaneously use the methods of evaporation and condensation. While heating the solution in a kettle, we observe that vapour or steam starts to rise from the spout of the kettle. What we then do is allow this steam to come in contact with a metal plate which has some ice on it. When this happens, the steam gets converted to small drops of water which we transfer to another container and thus successfully manage to separate salt which gets left behind in the kettle and the water which we collect in a separate container.

Condensation is the defined as the simple process of converting gas or vapour to its liquid form by decreasing the temperature or pressure exerted on it. This is what we did when we allowed the steam to come in contact with the cold metal plate

Figure 9 Use of more than one method of separation

Can Water Dissolve Any Amount of a Substance?

Even though water can dissolve a number of substances and solutions in it, it has a limit to how much it can dissolve. After a certain point, it stops dissolving any more of that substance and the substance collects at the bottom of the vessel. We say that the solution has become saturated.

A saturated solution is one that contains the maximum possible concentration of a particular solute. For example, if we continue to add increasing amounts of salt to a small quantity of water, there will come a point that the salt will not get mixed with the water and instead deposit at the bottom. At this point, we say that the solution has become saturated i.e. it is now incapable of dissolving any more of the given solute which is in this case, salt.

A salute is defined as a very small element in a solution that is dissolved in a solution.

One way of ensuring that the given amount of water takes more salt even after it has reached its saturation point is by heating the said water. This is because heating the solution helps to increase the solubility of salt or any solute and hence more amount of the same solute can now be dissolved in the same amount of water.

Some Important Definitions

Churning: The process of shaking milk or cream in order to allow lighter particles to come to the surface in order to make butter is called churning.

Pure Substance: This can be defined as a substance composed of only a single type of particle.

Impure Substance: A substance composed of more than one type of particles.

Sublimation: When a solid directly gets converted into vapour, this process is known as sublimation.

Magnetic Separation: This is another method of separation which allows metals (and other articles which are attracted to a magnet) to be separated from a mixture with the help of a magnetic or by applying a magnetic force to it. For example, a mixture of salt and iron filings can be separated with the help of a magnet.

Objects Around Us

When we look around, we find ourselves surrounded by a number of objects. Some of these different objects are made from a number of different materials, while others are made using the same material. For Example, both desk and chair are made from wood while pen and dustbins are made using plastic. The material from which an object is made depends on its properties.

Properties of Materials

1. Appearance

Materials can be classified on the basis of how they look or appear to be. Some materials have lustre, which is a very gentle sheen or soft glow to them while others are plain and dull looking. Materials that have such lustre can usually be classified as Metals. Examples include gold, copper, aluminium, iron etc. Usually, a metal loses its lustre after some time due to the action of moisture and air on it. Therefore only freshly-cut metals appear to have lustre on them.

2. Hardness

Materials can also be classified on the basis of hardness.

Materials that can be easily compressed or scratched are called Soft.

Materials that cannot be scratched and are difficult to compress are termed as Hard.

3. Soluble or Insoluble

Materials that can be dissolved in water upon stirring are said to be soluble materials. For Example, Sugar and Salt can be dissolved in water.

Materials that cannot be dissolved in water no matter how much we stir them are said to be insoluble materials. For Example, Stones and Clothes cannot be dissolved in water.

Not just solid materials, even liquids have the property of being soluble or insoluble. For Example, Lemon juice can easily dissolve in water while oil does not dissolve and deposits as a thin layer on the uppermost layer of water.

4. Objects may float or sink in water

There are some insoluble objects or materials which sink to the bottom of the surface when dissolved in water while some other float on the surface of the water. For Example, leaves and corks float in water while rocks and coins sink in water.

5. Transparency

Objects or materials which can be seen through are said to be transparent objects. For Example, Glass, clear water and some plastics can be seen through and are hence transparent materials.

Objects and materials through which things can be seen but only partially are called Translucent objects. Butter paper and frosted glass are some examples of translucent objects.

Objects which cannot be seen through are known as opaque objects. For Example, Metals, wood and cardboard are some examples of opaque materials as you cannot see through them.

Thus, we can group objects on the basis of their appearance, whether they are hard or soft, whether or not they can be compressed, if they dissolve in water or not and if they don’t do they float or sink and lastly if they can be seen through clearly, partially or at all. In this way, materials can be grouped on the basis of their similarities and differences.

Why do we need to group objects?

We need to group objects for a number of reasons:

• Convenience to store: We often group objects in order to store similar objects together in order to make locating them easier in the future. Even in our homes, we store spices together in the kitchen while storing washing products in our bathrooms.
•  Convenience to study: We also group objects so that it becomes easy for us to study their features as well as the patterns of these features.

Variety in Fibres

Yarn: Yarn is defined as a long, twisted and continuous strand composed of interlocked fibres or filaments which are used in knitting and weaving to form cloth.

Fibres: The thin threads or filaments which form a yarn are called Fibres.

Where do fibres come from?

Fibres can be broadly classified into two broad categories:

Natural Fibres: Fibres that come from plants and animals i.e. are found in nature are called Natural Fibres. Examples:

• We get jute and cotton from plants.
• Wool is acquired from the fleece of a goat or sheep. It can also be acquired from the hair of yak, rabbits and camels.
• Silk fibre can be procured from the cocoon of silkworms.

Synthetic Fibres: Fibres that are made of chemical substances i.e. substances not found directly in nature are classified as synthetic fibres. Examples include nylon, acrylic and polyester.

	Natural Fibre	Synthetic Fibre
1.	Natural fibrers are fibers that are found in nature. Ex: Woo, Silk and Cotton etc.	These fibres are man made or simply prepared in lab. Ex: Nylon, Teflon etc.
2.	They are good absorbents and so able to absorb heat, temperature, cold, sweat etc. depending on conditions and nature of fibres.	They do not have such pores as they are made up of chemical and so do not act as good asorbents.
3.	No spinning process is required for filament production.	Melting, wet or dry spinning processes are used for filament production.
4.	Comfortable in use.	Not as comfortable as natural fibres.
5.	Their length is naturally obtained and it is not possible to change the fibre structure.	Their lengths can be controlled by man and the fibres can easily be changed to different structures.

Some Plant Fibres

1. Cotton

A field of cotton

Where does cotton wool come from?

• Cotton plants are grown in fields usually at places having a warm climate and black soil.
• Some cotton producing Indian states are Punjab, Gujarat, Madhya Pradesh, Karnataka, Maharashtra etc.
• Cotton plants bear fruits the size of a lemon called Cotton Balls which burst open upon maturing and the seeds wrapped up in cotton fibre become visible. Cotton is generally picked by hand from these balls.

Ginning: Ginning of cotton can be defined as the process of separating cotton fibres from cotton seeds. Traditionally, ginning used to be done by hand but these days machines called double roller cotton ginning machines are widely in use.

In the above figure, we see a boy ginning by hand.

2. Jute

A jute plant

• Jute fibre is obtained from the stem of the plant.
• Unlike cotton, jute is cultivated in the rainy season.
• Some jute producing Indian states are Bihar, Assam and West Bengal.
• The plant is harvested during its flowering stage.
• The stems of these harvested plants are then soaked in water for four to five days
• The stems are left to rot and then the fibres are picked out by hand.

Yarn: Yarn is the spun thread that is made from fibres in order to produce a fabric.

Spinning Cotton Yarn

Spinning: Spinning is the process of constructing yarn from fibres in which fibres from a huge heap of cotton wool are taken out and twisted which brings them together to form a yarn.

There are two major devices called Takli which is a hand spindle and Charkha which is also a hand-operated device, are used for spinning.

The spinning of yarn on a bigger scale is done using spinning machines following which these yarns are used to weave fabric.

Khadi was the term used to denote clothes which were made from homespun yarn.

On the left we can see a charkha and on the right we can see a simple takli.

Yarn to Fabric

There are two major ways using which yarn is converted to fabric, namely, Weaving and Knitting.

• Weaving: The process of entwining two sets of yarn simultaneously to make fabric is called Weaving. The process is done using a loom (which can either be operated by hand or by a machine) which interlaces two sets of yarn at right angles to each other.

The above figure represents the process of weaving. 

• Knitting: Knitting is the process by which a single strand of yarn is used to make a piece of fabric. Socks, sweaters, mufflers and a lot of other winter clothes are made of knitted fabrics. Knitting can be done by hand as well as by machines.

History of Clothing Material

• In earlier times, when people did not have access or the knowledge to process fibre, big leaves and the bark of trees were used by people to cover themselves.
• After settlement began in agricultural communities, they learnt how to weave. They used grass and twigs to make mats and baskets. Animal hair or fleece and vines were warped together into stretched out strands which were then woven into fabrics.
• There was an abundant growth of cotton in areas near Ganga, which the early Indians readily used to make fabrics for themselves.
• There is another plant named flax which yields natural fibres.
• The early Egyptians cultivated both cotton and flax and used them for creating fabrics. These plants grew near the river Nile.
• But in those days, people were not aware of the process of stitching. They simply used to wrap around the fabric around different parts of their bodies. Even today unstitched clothes like sarees, dhotis, lungis or turbans are widely in use.
• It was with the advent of the sewing needle that people learnt how to stitch fibres to make fabric.

Nutrients: A nutrient can be defined as components that are needed by our body to grow, survive and carry on different daily activities.

Our food contains mainly five major kinds of nutrients namely vitamins, minerals, carbohydrates, proteins and fats. Additionally, food also contains water and dietary fibres/roughage and water which are also required by our bodies.

Fig. 1: Major nutrients of food

Carbohydrates: Carbohydrates main function is providing energy to the body. These are found in our food in the form of sugar and starch i.e. simple and complex carbohydrates. Example It is found in bread, potatoes etc.

Simple Carbohydrates: These are also referred to as simple sugars, containing single monosaccharide units and found in natural sources of food i.e. milk, fruits and vegetables. These carbohydrates add certain sweetness to the food. They raise the level of blood glucose quickly but are easier to break down.

Complex Carbohydrates: These are also referred to as polysaccharides, meaning they contain hundreds or thousands of such monosaccharide units. These are typically found in wheat grain, white bread, kernel and cakes. They are relatively less sweet than simple carbohydrates and also raise blood glucose level rather slowly. However, these are tougher to break down. Cellulose is present in plant cell wall. It is a complex carbohydrate. Humans cannot digest cellulose.

Test for carbohydrates: We can test whether a particular food item contains carbohydrates by pouring 2 to 3 drops of dilute iodine solution on it. If the iodine changes its colour to blue–black, then we can ascertain that the food item does, in fact, contain carbohydrates.

Fig.2: The Two Types of Carbohydrates

Proteins: Proteins performs the very essential function of helping our body grow and repair itself. These are found in food items such as milk, pulses, eggs, meat etc. Foods containing proteins are called ‘body-building’ foods.

Test for proteins: To test whether a food item contains proteins, first we need to grind it into a paste or powder form and add 10 drops of water. To this mixture when we add 2 drops of copper sulphate solution and 10 drops of caustic soda solution. After a few minutes, if the mixture turns violet, it is indicative of the presence of protein.

Fats: Fats are also responsible for providing energy to our body. In fact, they provide more energy than carbohydrates. The body uses fat as a fuel source. Fats are essential for the absorption of vitamins A, D, E and K in the body.  Butter, cheese, oil are all examples of fat-rich foods.

Test for fats: To test for fats, take a small quantity of food item and wrap a piece of paper around it and proceed to crush it. After removing the paper, allow it to dry. If you see a film of an oily patch on the paper when holding it against light, it is proof that the food contains fats.

Vitamins: Vitamins help in protecting our bodies from various kinds of diseases. They also help in keeping our eyes, gums, bones and teeth in good shape. Different types of vitamins and their uses:

Vitamin Type	Sources	Functions	Deficiency Diseases
Vitamin A	Leafy green vegetables, oranges, carrots, Pumpkin, Soy, Sweet potatoes	Forms and helps maintain bones, skin, tissue and teeth	Color blindness, night blindness- poor visibility at night.
Vitamin B1 (thiamine)	Dried herbs, sunflower seeds, whole grain cereals, sesame seeds, brown rice	Enables cells to turn carbohydrates into energy	Beriberi-  loss of appetite, loss of weight.
Vitamin B2 (riboflavin)	Almonds, Asparagus, bananas, green beans, wheat bran, dried spices	Maintains Body growth and RBCs i.e. Red Blood Cells	Skin disorders, Cheilosis-breaking of lips
Vitamin B12 (cyanocobalamin)	Mutton, fish, beef, lobster, clams, eggs, oysters, crab	Helps in maintenance of central nervous system and RBCs	Pale skin, lack of RBC, Less stamina and less appetite.
Vitamin C	Fresh herbs, cauliflower, papaya, oranges, strawberries, guava	Promotes healthy gums and teeth	Scurvy i.e. gum disease (gingivitis).
Vitamin D	Sunshine, Mushrooms, liver, fish and eggs	Necessary for the healthy development of bones and teeth	Rickets and Osteomalacia – weakening and softening of bones.
Vitamin E	Soyabean oil, red chilli powder, pine nuts, apricots, green olives and cooked spinach	Helps in processing vitamin K and formation of RBCs	Muscle weakness and transmission problems in nerve impulses
Vitamin K	Green leafy vegetables, Soyabean oil.	Essential for blood coagulation	Excessive bleeding from wound.

Minerals: Minerals are used by the body to perform various functions like building strong bones, maintaining the heartbeat, making hormones etc. The major five minerals are Calcium, Phosphorus, Magnesium, Sodium and Potassium. Examples of mineral-rich foods include leafy vegetables, fish, beans etc.

Mineral Type	Sources	Functions	Deficiency Disease
Calcium	Tofu, Dairy products, Salmon, Cabbage, Kale and Broccoli	Essential for efficient functioning of nervous system and healthy bones	Weak bones,  lower than normal bone density and stunted growth
Phosphorous	Lean meats, grain and milk	Essential for the maintenance of acid-base balance in body	Loss of appetite, bone fragility, muscle weakness, poor physique
Iodine	Green leafy vegetables, Seafood, iodised salt	Formation of thyroid hormone	Goitre- Enlargement of thyroid gland, mental disability.
Sodium	Table salt, celery	Helps keep control on blood pressure	Nausea, irritability
Iron	Whole grain, eggs, leafy vegetables and meats	Essential for haemoglobin formation in rbc.	Anaemia – weakness, fatigue, shortness of breath

Fig.3: The five major minerals and their source foods

Dietary Fibres/Roughage: While dietary fibres do not provide any such nutrition to our bodies but nevertheless are an important component of food. They help in easy absorption of food, helps in movement of bowel and prevents constipation. It helps our body get rid of undigested food. Cereals, fruits and vegetables are some of the roughage rich foods.

Water: Water performs the essential function of absorbing nutrients from our food. It also helps in releasing waste from our body in form of sweat and urine.

Balanced Diet

A balanced diet is one that contains a variety of food items providing different types of nutrients in adequate amounts necessary for maintaining good health. The diet should contain a good amount of dietary fibre and water as well.

A balanced diet includes a combination of protein-rich pulses, sprouted seeds etc. with combinations of various flours and cereals for carbohydrates and fats along with fruits and vegetables which provide the necessary vitamins and minerals.

• In addition to making sure that the right amount of food is eaten, it should also be ensured that food is properly cooked so that it does not end up losing its nutrients.
• Repeated washing of fruits, pulses, rice and vegetables can result in the loss of essential vitamins and minerals.
• Throwing away excess water which is used for cooking vegetables can result in the loss of considerable amounts of important proteins and minerals present in them.
• It’s a well-known fact that vitamin C gets destroyed in the heat while cooking.

Obesity: Obesity is a medical condition that results from excess intake of fat-rich foods. The excess fat gets accumulated to such an extent that it starts negatively affecting one’s health, well-being and the ability to carry out certain activities.

Deficiency Diseases

Deficiency: Sometimes simply getting adequate amounts of food might not be enough if the food does not contain the required nutrients in the right amounts. Prolonged usage of such nutrient-less food may result in a condition known as Deficiency.

Deficiency Diseases: Diseases that occur from the lack of an element in the diet, usually a particular vitamin or mineral are known as deficiency diseases.

• A diet lacking proteins may result in skin diseases, stunted growth, diarrhoea, swelling of face and discolouration of hair.
• A diet deficient in both carbohydrates and protein may hinder the growth completely and the person becomes so frail and lean that he or she might not even be able to move.
• Deficiency of certain vitamins and minerals can cause diseases like scurvy, goitre, anaemia etc. as mentioned in the tables above.

Hence one must always make sure to include all nutrients in their food and drink a good amount of water to maintain a healthy body that is free from diseases.

Malnutrition

Improper intake of nutrient-rich food may lead to another condition called malnutrition or undernutrition. Without adequate intake of food, our bones become brittle, our muscles weaken and our thinking becomes foggy. In such situations, our bodies are said to become malnourished.

When there is lack of protein in our bodies, repair of wounds and an injury becomes difficult. When this is combined with inadequate intake of calories, it leads to a condition known as Protein-energy Undernutrition or malnutrition.

There are two ways in which protein-energy malnutrition manifests itself:

Fig.4: Two types of protein-energy malnutrition diseases

Kwashiorkor: People with severe protein deficiency are often at high risk of developing this disease. People in rural areas are more likely to suffer from this disease, as there is lack of protein rich food. If one often indulges in diets that are high on carbohydrates and low on protein it can lead to them showing symptoms of kwashiorkor i.e. Edema (puffy appearance due to retention of fluid), inability to gain weight and bulging of abdomen.

Marasmus: Children and young adults are more likely to develop this disease. If there is inadequate intake of both energy and protein, it tends to manifest as marasmus. Chronic diarrhoea, weight loss, dehydration and stomach shrinkage are the major symptoms of marasmus.

Food Materials and Sources

Plants act as sources of food ingredients such as fruits, vegetables, grains, pulses etc.

Animals are sources of food ingredients such as milk, eggs, meat products etc.

These are shown in the figure above.

Some examples of edible plant parts are shown in the image above and their examples are given below:

• Roots: beets, carrots, radishes, turnips, ginger,
• Stems: broccoli stem, bamboo shoots, sugar cane, potato
• Leaves: spinach, lettuce etc.
• Fruits: apple, pear, tomatoes, grapes, cherries, oranges
• Edible Flowers: broccoli heads, cauliflower heads
• Seeds: sunflower seeds

What do Animals Eat?

Animals can be classified into three broad categories in terms of what they eat as can be seen in the image above,

First we have the herbivores i.e. plant eaters. They only consume plant parts. Examples: Cows, goats, deer, giraffe etc.

Next we have the carnivores i.e. meat eaters. They only consume meat of other animals. Examples: Lions, tigers, vultures etc.

Last we have omnivores i.e. animals who eat both plant parts and meat products. Examples: Humans, bears etc.

There are five major components of food namely vitamins, minerals, proteins, carbohydrates and fats. While the diet of carnivores is rich in fats and proteins, there are some necessary vitamins and minerals in plant-based foods that their diet lacks. Similarly an all plant-based diet lacks in a good amount of protein and certain minerals.

It is important to know that there is difference between vegetarians and herbivores. While vegetarians make a conscious decision to not eat meat, herbivores on the other hand are incapable of eating meat and dairy products. Similarly carnivores lack the necessary enzymes in their stomachs to digest cellulose which is a major component of green food like grass. 

Important Definitions

Nectar: The juicy sweet liquid secreted by within flowers which is sucked by bees and is made into honey by them

Sprouting: The process by which seeds shoot out small white structures as way of growth is called Sprouting.

Cellulose: It is a substance that is found in the cell walls of a number of plants. It is an indigestible fibre and is found in grass.

Enzymes: It is defined as a chemical substance that helps in bringing about changes to certain other substances without undergoing any changes in themselves.

A bowl of sprouts

Geometry tells us about the lines, angles, shapes and practical geometry is about the construction of these shapes.

Tools to be used for construction

1. The Ruler

A ruler is a straight edge which we sometimes call a scale. It is marked with the centimetres on one side and inches on the other side. It is used to draw line segments and also to measure them.

2. The Compass

The compass has two ends –one is a pointer and the other is for the pencil. It is used to draw arcs and circles and also to measure the line segment.

3. The Divider

It is a pair of pointers on both the ends. It is used to compare the length of line and arcs.

4. Set -squares

It is a set of two triangular pieces.

• One is having 45°, 45° and 90° angles at the corners. If we join two same triangular pieces, we will get a square. It is used to draw parallel and perpendicular lines.

• Other is having 30°, 60° and 90° angles at the corners. If we join two same triangular pieces, we will get a rectangle. It is also used to draw parallel and perpendicular lines.

5. The Protractor

It is a semi-circular device which is divided into 180-degree parts. It starts from the 0° from the right-hand side and ends with the 180° on the left-hand side and vice versa. It is used to measure and draw angles.

The Circle

It is a round shape in which all the points of its boundary are at equal distance from its centre.

Construction of a circle if the radius is known

Draw a circle of radius 5 cm.

To draw a circle, we need a compass and a ruler to measure the length.

Step 1: Open the compass and measure the length of 5 cm using a ruler.

Step 2: Mark a point O, which we will use as the centre of the circle.

Step 3: Put the pointer on the point O.

Step 4: Turn the compass to make a complete circle. Remember to do it in one instance. 

A Line Segment

A line segment is a part of a line which has two endpoints. It has a fixed length so it can be measured using a ruler.

1. Construction of line segment if the length is known

Draw a line segment of 5 cm.

To draw a line segment of a particular length, we need a compass and a ruler.

Step 1: First of all draw a line l of any length and mark a point named A on it.

Step 2: Measure the length of 5 cm by putting the compass on the ruler. Put the pointer on 0 and open the compass till 5 cm on the ruler.

Step 3: Put the pointer at point A on the line and draw an arc of 5 cm which intersects the line at B.

Step 4: Hence the line segment of 5 cm is

2. Construction of a copy of a given line segment

To make a copy of a line segment, there are three methods-

1. Measure the length of the given line segment using a ruler and draw the line segment of the same length with the ruler only.

2. Take a transparent sheet and trace the given line on another part of the paper.

3. These methods are not very accurate so we can use a ruler and compass to make an accurate line segment.

Draw a copy of the line segment

Step 1: is the given line segment whose length is known.

Step 2: Use the compass and put the pointer on A. open the compass to place the pencil side on point B. Now the open compass is of the same length as given

Step 3: Draw a new line l and mark a point C on it. Put the pointer on the point C.

Step 4: Using the same radius draw an arc on line l which cuts the line at the point D. 

Perpendiculars

If two lines intersect in such a way that they make a right angle at the point of intersection then they are perpendicular to each other.

1. Perpendicular to a line if a point is given on it (using a ruler and a set square)

Step 1: A line l is given and a point P on it.

Step 2: Put the ruler with one of its side next to l.

Step 3: Put the set square with one of its sides by the side of the already aligned edge of the ruler so that the right-angled corner comes in contact with the ruler.

Step 4:  Slide the set-square so that the right-angled corner coincides with P.

Step 5: Hold the set-square. Draw PQ along the edge of the set-square.

PQ is the required perpendicular to l from the given point P.

2. Perpendicular to a line if a point is given on it(using a ruler and compass)

Draw a perpendicular of the line at a given point A.

Step 1: Take A as the centre and draw a big arc with any radius so that it intersects the line at point B and C.

Step 2: Take B as the centre and draw an arc with the radius more than AC and then take C as center and draw an arc so that they intersect each other at point D.

Step 3: Join AD. AD is perpendicular to CB.

AD ⊥ CB.

3. Perpendicular to a line from a point which is not on it(using ruler and a set square)

Step 1: P is the point outside the given line l.

Step 2: Put the set-square on l so that one side of its right angle comes on l.

Step 3: Put a ruler on the hypotenuse of set square.

Step 4: Hold the ruler and slide the set-square until it touches the point P.

Step 5: Join PM.

Now PM ⊥ l.

4. Perpendicular to a line from a point not on it (using ruler and a compass)

Step 1: P is the point outside the given line l.

Step 2: Take P as the centre and draw a big arc of any radius which intersects line l at two points A and B.

Step 3: Take A and B as radius and draw arcs from both points with the same radius as taken before so that they intersect with each other.

Step 4: Join PQ.

PQ is the perpendicular to line l.

5. The perpendicular bisector of a line segment (using transparent tapes)

A line which divides the given line into two equal parts is known as a perpendicular bisector.

Step 1: Draw a line segment AB.

Step 2: Take a strip of transparent rectangular tape and put it diagonally on the line AB so that the endpoints of the line segment lie on the edges of the tape.

Step 3: Take another strip and put it over A and B diagonally across the previous tape so that the two tapes intersect at point M and N.

Step 4: Join MN. MN is the perpendicular of AB.

6. The perpendicular bisector of a line segment (using ruler and compass)

Step 1: Draw a line segment AB.

Step 2: Take A as the centre and draw two arcs – one upside and one downside with the radius of more than half of the length of AB. Or you can draw a circle taking A as the centre for the convenience.

Again make the arcs with taking B as the centre so that they intersect the previous arcs.

Step 3: Join the intersections of the arcs and name them as C and D.

Step 4: The required perpendicular bisector of AB is CD. Hence, AO = OB.

Angles

Angle is a stature formed by two rays. The two rays have a common endpoint which is called the Vertex of the Angle.

1. Construction of an angle with a given measure

Draw an angle of 60 ° using a protractor.

Step 1: Draw a line BA.

Step 2: Put the protractor on the line in such a way that the centre of the protractor lays on point B and the zero edge comes on the line segment BA.

Step 3: Start from 0° and mark the point C at 60°.

Step 4: Join BC.

∠CBA is the required angle.

2. Construction of a copy of an angle of unknown measure (using a ruler and a compass).

Draw a copy of ∠A.

Step 1: P is a point on the line l.

Step 2: Take A as the centre in the given angle and draw an arc of any radius which cuts the two rays at B and C.

Step 3: In the line l, take P as the centre and draw an arc with the same radius as above which cuts line l at Q.

Step 4: Open your compass to take the length of the arc BC.

Step 5: Take Q as the centre and draw an arc with the same radius, to cut the arc drawn earlier, at point R. 

Step 6: Join PR. It will make the angle of the same measure as given.

Hence, ∠P = ∠A

3. The bisector of an angle

An angle bisector is the line segment which divides a particular angle into two equal parts. It is also called the line of symmetry of the angle.

Construction of angle bisector (using a ruler and a compass)

Draw the angle bisector of ∠O.

Step 1: Put the pointer on O and draw an arc of any radius so that it cut the rays at point A and B.

Step 2: Put the pointer on point A and draw an arc of the radius of more than half of AB.

Step 3: While taking B as the centre we will draw an arc of the same radius so that it cut the previous arc at point C.

Step 4: Join OC.OC is the required angle bisector of ∠O.

Hence, ∠BOC = ∠COA.

4. Angles of special measures

There are some angles which we can construct accurately with the help of a compass without using a protractor.

a. Construction of 60° angle.

Step 1: Draw a line m and mark a point C on it.

Step 2: Take C as the centre and draw an arc of any radius to cut the line at point D.

Step 3: While taking D as the centre we need to draw an arc of the same radius to cut the previous arc.

Step 4: Join CE. ∠C = 60°.

b. Construction of 120° angle.

It is the twice of 60° angle.

Step 1: Draw a line m and mark a point C on it.

Step 2: Put the pointer on point C and draw an arc of any radius which cuts the line m at point D.

Step 3: While taking D as the centre we need to draw an arc with the same radius to cut the previous arc at E.

Again take E as the centre and draw an arc of the same radius to cut the first arc at point F.

Step 4: Join CF. ∠FCD = 120°.

c. Construction of 30° angle.

To construct an angle of 30°, we need to draw an angle of 60° as above then bisect it with the process of an angle bisector.

d. Construction of 90° angle

It can be made by two methods-

i. Draw a perpendicular bisector of 180° i.e. a straight line.

ii. Draw a bisector of 60° and 120°.

e. Construction of 45° angle.

Draw an angle of 90° then bisect it to make an angle of 45°.

When we fold a paper in such a way that the picture is divided into two equal halves then the line which divides the picture into two halves is called a Line of Symmetry.

Here the line divides the star into two halves so it is the line of symmetry. It is also called the Mirror Line because if we place the mirror on that line then one side of the picture will fall exactly on the other side of the picture.

Non-symmetrical Figure

This figure is not symmetrical as if we fold the image from the dotted line then it does not divide it into two equal halves.

Making Symmetric Figures: Ink-blot Devils

To make an ink-blot pattern-

• Take a piece of paper and fold it in half.
• Put some drops of ink on one side of the paper.
• Then press the halves together.
• It will make a symmetric pattern with the fold as the line of symmetry.

Inked-string pattern

To make an inked string pattern-

• Take a piece of paper and fold it in half.
• Dip a string in different colours and arrange it on the one side of the paper.
• Press the two halves together and pull the string.
• It will make a symmetric inked string pattern with the fold as the line of symmetry.

Two Lines of Symmetry

Some figures have two lines of symmetry.

1. A Rectangle

Take a rectangular sheet and fold it horizontally in two equal halves and then again fold it vertically in two equal halves. After opening it, we get two lines of symmetry of the rectangular sheet.

2. More Figures with two Line of Symmetry

If we take a rectangular piece of paper and double fold it to make two lines of symmetry and cut it in some new shape then after opening it we will get a new image that too with the two lines of symmetry.

Construction of figure with two Lines of Symmetry

1. To draw a figure with two lines of symmetry, take one figure.

2. Let L and M be the two lines of symmetry.

3. Draw the figure in such a way that L is the line of symmetry,

4. Now complete the figure by drawing the remaining part so that M will also become the line of symmetry.

Hence this is the final figure with two lines of symmetry.

Multiple Lines of Symmetry

Take a square sheet of paper and fold it in two halves vertically and again horizontally .open it and fold it in two equal halves diagonally then again open it and fold it along another diagonal.

When you will open the paper you will see four imaginary lines and these lines are the lines of symmetry.

Some more images with more than two lines of symmetry

• Equilateral triangle will have three lines of symmetry.
• Square will have four lines of symmetry.
• Regular pentagon will have five lines of symmetry.
• Regular hexagon will have six lines of symmetry.

Some Real-life Examples of Symmetry

In Taj Mahal and the butterfly there is one line of symmetry and there are so many other things also in our daily life which are having one or more line of symmetry.

Reflection and Symmetry

The line of symmetry is also called Mirror Line because the mirror image of an object is symmetrical to the image. When we see an object in the mirror then there is no change in the length and angles of the object except one thing i.e. the image is opposite to the original image.

Some Examples of Reflection Symmetry

1. Paper Decoration

We can use a rectangular sheet to fold and create some intricate patterns by cutting paper.

2. Kaleidoscope

In Kaleidoscope, mirrors are used to create pictures having various lines of symmetry. Two mirrors strips forming a V-shape are used. The angle between the mirrors determines the number of lines of symmetry.

Example

Which alphabet will remain same after reflection symmetry? Check for R, C, N, A and T.

Solution

In the alphabet reflection symmetry, the alphabets look opposite in the mirror i.e. the alphabet written from right to left will appear as written from left to right.

Hence C, N and R will not look the same after reflection.

Hence A and T will look same after reflection symmetry.