Garbage is defined as the items or materials that need to be discarded because they no longer serve any purpose for us or are of no use to us.
Tonnes of garbage and is generated by us on a daily basis. Garbage is often associated with a pungent smell and a large amount of garbage may release fumes which are not healthy. Hence, we put such items in dustbins to be taken to faraway places so that our surroundings are clean and healthy.
Waste is generated by all of us and has four main sources:
Domestic: These constitute the kind of wastes that are generated by households, offices schools etc. and include food remains, fruit and vegetable skins, clothing items, used plastic items etc.
Industrial: These constitute the kind of wastes generated by power plants, chemical plants, cement factories, food processing industries, textile industries, each producing waste specific to the kind of industry they are a part of.
Agricultural: This constitutes the kind of waste that is produced by undertaking agricultural activities husks, expired medicines, fertiliser and pesticide containers etc.
Commercial: This constitutes the kind of waste generated by commercial enterprises including disposable plastic cutlery, food items, food packets, textiles etc.
Not all garbage can be classified as useless as there very well are products which can be reused or recycled. When garbage is taken away by the municipality, it is taken to a low lying and open area known as a landfill. Here, garbage is separated into two categories: the items that can be used again for some other purpose and items that cannot be used. The latter is then spread over the landfill and covered with a blanket of soil. Once full, it is converted into a playground or a park.
Image 1: A landfill
The useful components of the garbage can usually be classified into two categories: biodegradable and non-biodegradable wastes.
Biodegradable wastes are items such as egg shells, vegetable and fruit skin, tea leaves, waste food etc. which can be mixed with soil and roots over time by the action of certain microorganisms. This is usually not accompanied by a pungent smell. Now this mixture of soil and rotten organic materials can be used as manure to provide nutrients to the plants. This process of conversion of biodegradable waste into manure for plants is known as composting.
Non-biodegradable waste comprises of items that do not rot over time by the action of microorganisms. Examples of such items are metal scraps, plastics, glass etc.
Apart from these, there is another category of non-biodegradable waste also known as electronic waste or e-waste that is composed of electrical appliances or components that no longer serve their specified function and are hence needed to be reused, re-sold, recycle or disposed off. These are non-biodegradable as no action by any microorganism is effective in breaking them down.
Image 3: The correct way to dispose biodegradable and non-biodegradable waste
Garbage should be allowed to be processed by the authorities and not burnt because the burning of garbage releases toxic fumes which are harmful to the health of everybody.
Vermicomposting
Vermicomposting is the process of conversion of biodegradable waste into manure with the help of a special type of earthworms called red worms.
A layer of sand or chicken mesh is used as the base to which all types of biodegradable waste including dried leaves, husk, vegetable peels and remnants of fruit, dried animal excreta newspaper, cardboard etc. A little water is sprinkled on this layer. On preparing this mixture, add the red worms to it and covered with a layer of grass or a sheet of cloth.
The work, however, is not done yet. Red worms need to be fed. They do not have teeth. They have what is called a gizzard. This helps the worms grind their food.
Fruit and vegetable remains, tea leaves, grass etc. act as food for the red worms and should be buried 2-3 cm deep in the soil. In a day, a worm can eat up as much food as it weighs.
However, pickles, milk, vinegar and salty materials might help in the growth of disease-causing microorganisms and hence should not be added to the pit.
They should not be kept in a very hot or a very cold environment. Red worms need care and water. They have the potential to double up in a month’s time, given proper nourishment and care.
Image 4: Red worms
Image 5: Vermicomposting pit
The compost gets ready in three to four weeks’ time.
Recycling of paper
Recycling paper on a small scale is a relatively easy process. All we need to do is tear up the paper in small pieces in a bucket and pour water in it. Let it rest for a day and pound it to make a thick paste out of it. Spread this evenly over a wire mesh to allow the water to drain water. Peel this layered paste and then allow it to dry in the sun. Paper is ready.
Plastics – boon or curse?
The plastic problem is mounting day by day. A huge amount of plastic is thrown away carelessly on the street and in water bodies and such irresponsible disposal of plastic can cause a number of problems:
Animals and birds alike, in search of food, end up consuming some amounts of plastic due to which many of them end up choking on these.
Although plastic bags seem convenient to store food items, consuming these are very harmful to our health.
It gets worse when dirty and thrown away plastic bags are re-used upon mere dusting and washing them which is also very harmful.
Upon burning or heating, plastics give rise to toxic and dangerous fumes and gases, which can potentially cause cancer in humans.
Careless disposal of plastic on the roads also ends up choking the sewer and drainage systems.
Image 6: The plastic problem is very harmful for all beings alike
Plastic, while very harmful for the environment has become a very indispensable part of our daily lives and hence it becomes all the more difficult to replace or in some cases, even cut-back on our plastic consumption. Plastics have a lot of characteristic features which give it an edge over its metal counterparts.
Bioplastics have hence emerged as the most environment-friendly version of plastics which are made of biodegradable items such as corn starch, vegetable fats and oils and other kinds of food waste. Bioplastics take about three to six months to be decomposed fully as opposed to several hundred years taken by their synthetic counterparts.
After learning so much, it should be everyone’s top priority to do their bit in saving the environment:
3Rs- Reduce, Re-use and Recycle. Reducing the use of plastic and re-using harmless plastic to help reduce its over-production. Recycling paper and such articles whenever possible.
Carrying jute and cloth bags when carrying out errands to avoid the use of polythene bags.
Properly disposing plastic and polythene bags
Not using plastic products and bags to store eatables.
Never burning plastic or dry leaves etc. and disposing them properly.
Using registers and notebooks made of recycled paper as much as possible.
Avoid putting waste materials in polythene bags and throwing them on the street.
Adopting practices like recycling paper and vermicomposting to make the best use of biodegradable waste. This not only helps to reduce the waste that we produce but also becomes a valuable addition to the soil and helps in the nourishment of crops and plants.
The invisible gaseous medium around us, mainly constituted by oxygen and nitrogen is known as air. It is through this air that we are able to carry out the process of respiration. Air is transparent and colourless. It occupies space and is present all around us.
Atmosphere: The thin blanket of air surrounding the surface of the Earth is called the atmosphere.
The atmosphere is divided into five distinct layers on the basis of variations in temperature that changes due to increasing altitude. Air gets scant as we move up in the atmosphere. These are as follows:
Troposphere: This is the first layer to the atmosphere which is nearest to the surface and is responsible for weather conditions. The troposphere itself is said to contain about more than 75% of the atmosphere!
Stratosphere: This is the layer just above the troposphere which contains the ozone layer and where the aeroplanes fly and is also home to most of the clouds!
Mesosphere: This is the third and the coldest layer of our atmosphere and extends to a good 80 km above the surface of the Earth.
Thermosphere: This is the fourth and one of the hottest layers of Earth where temperatures go to a 1500o This is where the space shuttles go to study Earth from space! The air in this layer is very thin and about 99.9% of the atmosphere is said to lie below this particular layer.
Exosphere: This is the outermost layer of the atmosphere where molecules and atoms escape into space. Beginning at 480 km above the Earth, this layer then extends into the space.
Figure 1 The five layers of the atmosphere
Constituents of Air
Air is a mixture of a number of gases and some other particles such as:
Water Vapour: Air contains water vapour which helps maintain the water cycle. When air comes in contact with cold surfaces, it is these vapours that turn into or condense into droplets of water. The amount of water vapor in the air from place to place and time to time. At a normal 30°C for instance can contain say upto 4% of water vapour.
Oxygen: It is the oxygen in the air that helps humans and animals carry out the respiration process. Oxygen is also required for fire to keep burning. If we were to keep an inverted tumbler covering a burning candle, the candle will go off in a few seconds because of the lack of oxygen-containing air due to the tumbler. Dry air is said contain about 21% of oxygen.
Nitrogen: Dry air is said to contain about 78% of nitrogen. This component of air helps plants in their growth process.
Carbon dioxide: Carbon dioxide is a very small (only 0.04%) component of air and is a byproduct of respiration by humans and animals. Fire also uses up oxygen to burn and then produces carbon dioxide and a few other gases upon burning. This is why we feel suffocated if there is something burning inside a room. This happens due to an excess of carbon dioxide as the fire continues to burn in the room, choking out oxygen in the air.
Dust and Smoke: Smoke is another component given out when fire burns. It is very harmful and adds fine dust particles and a few other gases to the air. This is why industries use long chimneys in order to release this smoke in the air. But as we know this act is what contributes to air pollution in the environment.
Air also contains very fine dust particles which can be seen when a beam of light enters a dark room. The tiny particles flying around in the beam are actually these dust particles. It is hence advised by our elders to breathe only through our nose and not our mouths so that the fine hair and mucus in the nose is able to filter out these dust particles so that we don’t inhale them and harm ourselves.
Figure 2 The composition of the components of air
As we can see from the Figure above, Oxygen and nitrogen together make up 99% of air while the other components come up to a mere 1% of all air in our environment.
Availability of Oxygen in Water and Soil
It is often asked how animals under the soil and in water are able to breathe. The answer is that both soil and water have air dissolved in them.
When we heat or boil water, we often notice that bubbles start to form. These bubbles are in fact, an indication that air molecules are present in the water. When water is heated, the air dissolved in it escapes first followed by water itself getting converted into vapour. This is how animals living underwater are able to respire.
Figure 3 Air bubbles can be seen when water is heated
To see the presence of water in the soil, we take a small lump of it in a beaker and add water to it. We see bubbles coming out of it which as we discussed, is proof of the existence of air molecules in the soil. As water is added, it displaces the water molecules in the soil which we see in the form of bubbles. Animals make use of this air to breathe under the soil. Some animals make holes and burrows in the soil to help make pathways for air to enter the soil. When it rains heavily, earthworms and other animals come out of the soil because these pathways get blocked by the water and they need to come outside to find the air to breathe.
Figure 4 Air particles present in soil
Balance of Oxygen in the Atmosphere
It is common knowledge that humans and animals can’t survive without plants because they produce oxygen via photosynthesis. The balance of oxygen in the environment is thus maintained through the respiratory processes of plants and animals.
The importance of Air
Air has a number of uses:
The air which is in motion is known as wind. The wind is important for the rotation of windmills which help in drawing water from tube wells.
They also help in running flour mills.
Windmills are also used to produce electricity.
Insects and birds are only able to fly because of the presence of air
Boats, yachts, aeroplanes and parachutes also need air to sail and glide
Air has a very important role to play in the water cycle as well.
Figure 5 A windmill in action
It also helps in distributing the pollen and seeds from flowers of various plants.
Introduction: It is common knowledge that water is important on our Earth and without water, life as we know it would cease to exist. While Earth has an abundant reservoir of water, covering three-fourths of its surface, Freshwater is a mere 2.6% of the total water. Water is said to be a renewable resource but the rate at which humans and animals are using water, fresh water might be a scarce resource in the recent future. Our body is also made up of 70% water and we use water for a number of reasons from cooking to cleaning and of course drinking it. A lot of experts predict that the next World War will be fought over water!
Figure 1 Two-thirds of Earth’s surface covered with water
Where does water come from?
People living in different regions have different sources of the water that they use. While some draw it from wells, ponds and lakes directly, others like many of us receive water through taps via a network of pipes connected to these lakes, ponds and rivers.
Water Cycle
To know how these rivers get their water from we need to study a little about the water cycle and the processes of evaporation and condensation.
Evaporation: The process of conversion of water into its gaseous state i.e. vapours is known as evaporation.
Condensation: The process of conversion of vapours into water is referred to as condensation.
Water cycle can be defined as the process through which water gets evaporated from open surfaces like oceans and seas, gets condensed as it rises in the cool atmosphere and ultimately pours down as rain (precipitation) back into oceans, lakes, rivers and ponds.
Figure 2 Water cycle
Transpiration: The process of evaporation of water from the surface of the leaves into the atmosphere is defined as the process of transpiration. In this manner, plants also contribute to the water cycle.
It is through the process of water cycle that we are able to make use of the ocean water. Ocean water is saline in nature and hence cannot be used directly. When it gets evaporated, it leaves behind the salts and forms clouds.
As the warm air from these surfaces rises into the cold air of the atmosphere, saturation and condensation occur to form tiny droplets of water which result in cloud formation.
These clouds then lead to rainfall and snow which deposit in lakes, wells and ponds is then used by us to satisfy our needs. Apart of this rainwater gets absorbed by the soil, some of it gets evaporated while the rest seeps in the ground and becomes another source of water for us in the form of groundwater. Handpumps, wells and even lakes draw water from groundwater. The water cycle is a continuous process.
Excess v/s deficient rainfall
Intensity and duration of rain vary in different regions across the country. While rainfall is very important for irrigation and the continuous availability of water, excess rainfall can pose a number of problems. Due to excess rainfall, the water level of rivers and oceans rises which can potentially spread and submerge nearby cities and villages which poses a grave danger to both life and property. These are known as floods.
Figure 3 Floods posing danger to property and life
Similarly, deficient rainfall can also prove to be life-threatening. A lot of farmers in India continue to depend on rainfall to irrigate their fields. In case of deficient rain, soil and wells still continue to lose water through transpiration and evaporation and if it doesn’t rain for a prolonged period, fields can dry up because even the groundwater does not get replenished. These are known as droughts.
Figure 4 Dried fields as a result of droughts
Conservation of water
There are a number of reasons why water conservation needs to be a priority for everyone. Here are some of them:
Mostly all water is in the oceans in saline form and can’t be used directly
While the total water on Earth does not change, but the water available for us to use diminishes with overuse
When the groundwater goes below drastically, it cannot be accessed anymore
Water is required in industries and for production of food
The population growth is exponential but the water sources are only depleting
Figure 5 A few tips to help save water
Rainwater Harvesting
Rainwater does not always fall on soil or water sources; in fact, much of it falls on rooftops of houses and concrete roads and thus does not become a part of groundwater. Hence, a very important method has been devised to harvest rainwater so that it can be stored for future use:
Rooftop Rainwater Harvesting – In this method, rainwater that falls on rooftops is allowed to pass in a storage tank through pipes. This water might be dirty and hence not fit for direct use; hence it can be allowed to seep directly into the ground with the help of pipes.
Magnets are pieces of iron or other materials which exhibit the properties of magnetism i.e. the ability to attract other objects that contain iron. Compass needles, fridge magnets and MRI scanners are some common examples of magnets.
It is said that magnets were discovered after a shepherd named Magnes accidentally got his iron stick stuck to a rock. It was later discovered that the said rock had magnetic properties and was called Magnetite, named so after the shepherd.
These days magnets come in different shapes and forms such as: horseshoe magnet, bar magnet, cylindrical or a ball-ended magnet, needle magnet etc.
Magnetic and Non-Magnetic Materials
Magnetic Materials: Materials like nickel, cobalt and iron are called magnetic materials. These materials are attracted to magnets.
Non-Magnetic Materials: Materials like rubber, plastic, cloth, glasses etc. which are not attracted to magnets are referred to as non-magnetic materials.
Poles of Magnet
We can observe a very interesting property about magnets which is that when we try to attract iron filings or any other magnetic objects to a magnet, they always accumulate at the ends of the magnet.
This is because near the poles the magnetic field of the magnet is very strong.
A Magnetic field is defined as the region around a magnet within which the magnetic force acts. Being strongest at the poles, this is why magnetic objects get attracted to the ends of the magnet.
Magnetic fields around a bar magnet
Finding Directions
Another great property of a magnet is that it can prove extremely helpful in navigating directions. This is because a freely suspended magnet always points in the North-South direction.
This property of magnet is used to make a compass. A magnetic needle is placed inside a box with directions marked on it. It is allowed to rotate freely so that when the compass is kept at the position of rest, the needle points towards the north and south direction.
Steps to make own Magnet
Take a rectangular piece of iron. Place it on the table.
Take a bar magnet and place one of its poles near one edge of the bar of iron. Without lifting the bar magnet, move it along the length of the iron bar till it reaches the other end.
Lift the magnet and bring the pole (the same pole we started with) to the same point of the iron bar from which we began. Move the magnet again along the iron bar in the same direction as we did before.
Repeat this process about 30-40 times. The iron piece has become bar magnet.
Attraction and Repulsion among Magnets
Opposite or unlike poles i.e. North and the South Pole attract each and vice versa.
Similar or like poleslike north and north poles of two magnets repel each other. Same is the case with South poles of two magnets.
Attraction between opposite poles and repulsion between similar poles
Notes of caution
When heated, hammered or dropped from a height, magnets tend to lose their properties.
They become weak if they are not stored properly and hence:
Bar magnets should be stored in pairs separated by a small block of wood and their unlike poles facing the same side with a soft iron across their ends.
A piece of iron should be kept across the poles in case of a horseshoe magnet.
Magnets should be kept away from computers, mobiles, televisions etc.
Magnets should be handled with care and they should be stored properly
Electricity has become so common that sometimes we forget its immense applications.
Advantages of Electricity:
Light in our houses, offices, roads etc. even past sunset
To operate pumps which in turn have a lot of applications
Electrical appliances like refrigerator, fans etc.
Building houses, installing equipment etc.
Fig 1: Refrigerator {Electric Appliance}
Electric Cell and Electric Bulb
Features of an Electric Cell:
It is a small cylindrical structure which helps in operating the devices.
A small metal cap is placed on one side and a metal disc is present on the other side.
All cells have two terminals: Positive and Negative.
The metal cap and metal disc are positive (+) and negative (-) terminals of the electric cell respectively.
Chemical energy is converted into electrical energy inside a cell. When the chemicals are exhausted, the cell stops working.
Fig 2: Electric Cell
Features of an Electric Bulb:
The outer covering is glass and the base is metallic.
The part of the bulb which glows is called Filament and is made up of tungsten.
The filament is attached to two wires. One of the wires is connected to the metal case at the base and the other wire is connected to the metal wire at the centre of the base.
Base of the bulb and metal tip are the terminals of the bulb and they do not touch each other.
Fig 3: Electric Bulb
An Electric Circuit
Consider an electric cell and a bulb. The terminals of the cell are connected to the terminals of the bulb by the means of electric wires. Such an arrangement of cell and bulb is called an Electric Circuit. The circuit is said to be complete in this case because of which electricity will flow and the bulb will glow.
One should be careful while setting up an electric circuit. It should be done under supervision.
Electric Switch
Switch is an integral part of an electric circuit. It is a simple device which breaks or completes a circuit. When the switch is ‘on’, the circuit is complete. When the switch is ‘off’, current does not flow in the circuit. So an electric appliance will only work if the switch is ‘on’.
Fig 4: Switch on and off respectively
Electric Conductors and Insulators:
Conductors – Materials that allow electricity to flow through them easily.
Insulators – Materials that do not allow electricity to pass through them.
Human body is a conductor, so touch a current carrying wire is detrimental and so insulating it prevents from an electric shock.
Some examples of conductors are: Metals like copper, Iron
Some examples of insulators are: Rubber, Plastic
Fig 5: Danger Sign
This sign is used in areas which are near electric junctions as a warning.
→ It is a form of energy which is responsible for seeing objects.
→ When light falls on an object, some light get reflected, this reflected light come to our eyes and we are able to see an object.
→ Example: sun, torch, candle, fireflies and glow worm etc.
Sources of light
(i) Luminous object: The objects which emit their own light is called luminous object.
→ Example: sun, torch bulb, star
(ii) Non-luminous object: The objects which do not emit their own light is called non-luminous object.
→ Example: Moon, shoe, trees.
Types of materials transmit light
→ There are three types of materials which transmit light:
(i) Transparent (ii) Translucent (iii) Opaque
(i) Transparent
→ These objects allow light to pass through them in straight line completely.
→ We can see through these objects clearly.
→ Examples: air, water, etc.
(ii) Translucent
→ These objects allow light to pass through them partially.
→ The object is not clearly seen in translucent object.
→ Examples: Tissue paper, frosted glass, butter paper, etc.
(iii) Opaque
→ These objects do not allow light to pass through them.
→ We can’t see the object through this.
→ Examples: wall, door, trees etc.
Characteristics of light
→ Light travels in straight line
→ Light can be reflected
→ Light can be bent
→ The speed of light is 3 × 108 m/sec
→ Light can be polarized
Shadow
→ When an opaque object blocked the path of light it forms a dark portion on the opposite side of the object this dark portion is known as shadow.
Properties of shadow
→ The object must be opaque or translucent
→ Transparent object do not make shadow
→ It is dark in color
→ It is formed opposite to the source of light
→ It gives the information about the shape of object
→ Size of shadow can be increase or decrees by change in distance between object and screen are changed.
Pin hole camera
→ It is a toy device use to study light travels in straight line
Properties of image formed by a Pin Hole Camera
(i) Image formed by a pin hole camera is coloured.
(ii) Image formed by a pin hole camera is inverted.
(iii) Image formed by a pin hole camera is smaller in size.
Rectilinear propagation of light
→ Light travels in a straight line are called rectilinear propagation of light.
Important terms regard rectilinear propagation of light
(i) Ray of light: It is a path along which light travels in the given direction.
(ii) Beam of light: Bunch of ray of light travel in the given direction.
Mirror
→ A mirror is a polished surface which can make the image of an object.
Types of Mirror
(i) Plane mirror: Image formed is of the same size
(ii) Concave mirror: Reflecting surface is bent–in.
(iii) Convex Mirror: Reflecting surface is bulged-out.
Reflection
→ When light falls on a mirror, light wave may change their direction upon the striking surface this phenomena is called reflection.
Objects that do not produce their own light but are visible when reflect light falling on them are called Non-Luminous Objects. Example – Table, planets. Non-luminous objects can be classified as-
Shadows are dark regions formed when an opaque object blocks the path of light. This formation is possible only because light only travels in a straight line.
How to make a Pinhole Camera?
Step 1: Take two cardboard boxes one larger than the other such that one box slides into the other without any gap.
Step 2: Cut out open one side of each box. On the opposite side of the larger box cut a small hole in the centre.
Step 3: On the opposite side of the smaller box cut a square of about 5 cm and cover this open area with a tracing paper.
Step 4: Slide the smaller box inside the larger one such that the side with the tracing paper is on the inside.
Step 5: Cover the camera and your head with a black cloth and then get ready to observe the distant objects.
Fig: A Pinhole Cameria
It is a simple camera with a small aperture and forms an inverted image of the object.
Mirrors and Reflections
All of us are used to seeing a mirror every day. The image that we see in a mirror is called Reflection. The mirror deflects the direction of the light that falls upon it.
Fig: A Mirror Changing the direction of light as it falls on it
With the changing times, transport also has gone through various modifications i.e. from animals to the invention of wheels. The evolution of transport is evident when we observe the fast cars, bullet trains etc. Even today new modes of transport are being researched upon.
Fig 1: Shows the advancement in transport
Distance: How far an object travels constitutes distance!! The GPS system introduced these days accurately measures the distance from one place to another.
Arbitrary ways to measure the length or width:
Measuring using handspan and measurement by a string were used in ancient times but these methods are not so reliable and hence some standard units of measurement have been introduced.
Fig 2: The Handspan Method
Standard Units of Measurement
Earlier the ‘cubit’ was accepted as a standard unit in Egypt. A cubit meant the length between fingertips and elbow. Owing to the differences in the length of body parts of each person these arbitrary systems became obsolete. Other units used earlier were ‘foot’, end of outstretched arm and chin, fist, etc.
Nowadays, the International System of units or the SI units have been accepted all over the world as a standard unit of measurement.
1 m = 100 cm
1 kg = 1000 g
1s = 1/60 min
The MKS system i.e. the metre-kilogram-second system is called the SI System.
Correct Way to Use a Mater Scale
Step 1: Keep the scale in contact with the object to be measured.
Step 2: Start measuring from the 0 mark of the scale.
Step 3: To avoid taking incorrect measurements the eye position should be correct. Consider the following figure:
The eye position in the centre is correct to get an accurate measurement, while the ones in the left and right direction will give some error in measurement.
Measurement Along Curved Line
Is it possible to measure a curved line with a metre scale? Well, it is not so. Hence to measure a curved line the following steps can be taken into account:
Take a thread and tie a knot at one end.
From this end measure a small portion of the curved line which is somewhat straight and put the thumb.
Now again start from the thumb marked position and measure another small portion of the line.
Repeat this process until you reach the end of the line. Tie a knot on the thread on reaching the end. Now measure the two knots using a metre scale.
Fig 4: Measuring A Curved Line
Types of Motion
Rectilinear Motion: When an object moves along a straight line, it is said to be undergoing rectilinear motion. For Example, A train moving along a railway track.
Circular Motion: Have you seen the hands of a clock? The motion exhibited by the hands of a clock is called Circular Motion.
Periodic Motion: When an object repeats its motion after a fixed interval of time it is said to be undergoing periodic motion. For Example, Pendulum
Rotational Motion: This motion can be easily understood by imagining Earth’s rotation. When the Earth spins on its own axis it is said to be undergoing rotational motion.
Motion is defined as the change in position of an object.
Introduction: Different regions in the world have various types of living creatures called organisms. Even the openings of volcanoes have tiny living organisms. Even our homes are not devoid of these tiny organisms. List some of the tiny organisms which you have encountered at home!
Environment: Everything that we see surrounding us; living, non-living, physical, chemical etc. is called as environment
Biotic Components: These are the living components of the ecosystem. e.g. flora and fauna
Abiotic Components: The non-living components of the ecosystem like soil, water ,air etc. are called abiotic components.
Organisms and the surroundings where they live
The table shows some common organisms and their place to live
ORGANISM
WHERE THEY LIVE
CAMELS
DESERTS
YAK
MOUNTAINS
CRABS
SEA
ANTS
VARIOUS LOCATIONS
Habitat and Adaptation
The region or place where an organism lives is termed as its habitat.Habitat provides an organism everything it needs to survive like food, shelter, proper weather conditions such as rainfall, heat etc to breed and flourish.
Camel:
It has long legs which provide protection from the heat of sand
Excrete small quantity of urine
They do not sweat and their dung is dry
Can live without water for many days as their bodies lose little water.
Figure 1 Camel
Fish:
Their streamline shape helps to move easily in water
Presence of slippery scales
Gills help in utilizing dissolved oxygen
Flat fins and tail help in changing direction in the water
Figure 2 Aquatic Organisms
Both the organisms discussed above have specific features or characteristics that enable them to survive in their habitat. These features are termed as adaptations.
TERRESTRIAL HABITAT:Plants and Animals that thrive on land said to live in terrestrial habitat.E.g.: forests, deserts, mountain regions
AQUATIC HABITAT:Plants and Animals that thrive in water said to live in aquatic habitat.E.g.: rivers, lakes
Journey through different habitats
Terrestrial Habitat:
a) Deserts:
The following adaptations of various organisms are enlisted below:
Snakes and rats dig burrows to escape intense heat as they dont have long legs such as a camel. These animals come out only during the night, when it is cooler
In desert plants leaves are reduced to spines and lose little water through transpiration
The stems of desert plants have a waxy coating on them and in most of them photosynthesis is carried out by the stem
Their roots go deep into the soil so as to absorb water.
The leaves in desert plants are absent to prevent loss of water due to transpiration.
Some of the animals are camels, kangaroo rats etc
b) Mountain Regions:
The trees are cone shaped with slope like branches, also needle-like leaves are present so that rain and snow slide off them easily.
Animals have thick fur which provides protection from cold. e.g. Snow Leopard
Presence of strong hooves help the mountain goat to run on the rocky slopes.
Eg are Pines, mountain goats, yaks, sheep etc. Yaks have long hair to keep them warm.
Figure 3 A tree found in mountain region
c) Grasslands:
The light brown colour of the lion helps it to hide in dry grasslands and the presence of long claws help to capture the prey.
Deer has strong teeth to eat plant stems also its long ears help to listen to predator movement. They have eyes on its sides of the head which help them to look in all directions to lookout for danger.
Some of the animals living in these habitats are elephants, giraffes, lions .
d) Rainforest:
This habitat receives a lot of rain and hence its rich in animal life.
Mammals, Amphibians, Reptiles all sorts of animals are found here.
The climate is hot and humid and animals have to learn to adapt to survive.
e) Polar Habitat:
These habitats are very cold and windy.
The animals are mostly carnivores and have thick fur to survive in cold.
Some blend in ice and some may hibernate in the coldest months.
Examples of animals are polar bears, reindeers, penguins etc.
Aquatic Habitats
Figure 4 An aquatic plant
Marine Habitat
Marine Habitat comprises of oceans and seas, and both have saltwater.
They are home to a wide variety of creatures like the most part of fish population is found here.
Marine creatures are found in Estuaries – where rivers and oceans meet and the water is salty.
Marine Mammals like whales migrate to long distances in order to cope up with the temperature changes.
Oceans
Most organisms have streamlined bodies and gills
Octopuses do not have streamlined bodies so they stay deep in ocean, but when moving they make a streamline motion.
Whales have blowholes instead of gills This enables them to breathe easily when they swim near the surface of water.
Figure 5 An Octopus
Freshwater Habitat:
Rivers, lakes, ponds etc comprise the freshwater habitats.
Three percent of world’s water is accounted as freshwater but still a wide variety of species are found here.
Snails, worms, mollusks etc are found in this habitat
Ponds and Lakes:
Plants: Water plants can be completely submerged in water (like Hydrilla) or floating on the surface of water(like Water Lily, Lotus, Water Hyacinth). Roots are much reduced in size, since their main function is to hold the plant in place. Stems of aquatic plants are long, hollow and light so that these can bend in along with water movement. e.g Water Lily. The stems grow up to surface of water, while the leaves and flowers float on surface of water.
Totally submerged plants have narrow and ribbon like leaves (e.g tape grass). These can bend in flowing water.
Stems have air spaces to enable the plant to float. Floating plants are large and flat. They have waxy upper surfaces that makes them waterproof. They have stomata on the upper surfaces which are exposed to air.
Frogs are adapted to live both on land and water, they have strong back and legs and webbed feet which allows them to swim in water.
Coastal Habitat:
Habitats where the land meets the sea.
Beaches, special type of trees called mangroves are found in this habitat
Coastal plants like seaweed attach to the rocks firmly so that they are not swayed by the waves,
Acclimatisation: Due to certain changes in the surroundings, organisms adapt through them by making small changes in the body over short periods of time.
For e.g: The changes which take place in the body when we travel from plains to mountains. The adjustment which the body makes is called Acclimatisation
Characteristics of Living Organisms
Living
They require food to grow and carry out life processes
They grow in size
All living organisms breathe and respire(process of generating energy)
They Respond to stimuli(changes in environment)
They carry out reproduction(producing next generation) and excretion(elimination of waste from body)
The human skeleton is the internal framework which is responsible for giving support, shape and protection to our bodies. It contains 206 bones, each playing a distinct yet important task. The skeleton can be classified into two parts called as the axial and the appendicular. The axial skeleton comprises of the central part of the skull, spine, and ribs and the appendicular skeleton consists of the arms and legs.
Terms –
Limbs: The arms or legs of an animal.
Bones: These are the hard white structures below our skin that protect our internal organs. Bones are incapable of bending.
Joints: These are defined as the points at which two bones are fitted together. These are the points at which we can rotate and bend our bodies.
Figure 1: Body Movements
Types of Joints and their Location in Human Body
A Pivot joint is a joint that rotates.. Examples of pivot joints in the body in the neck that allows the head to rotate and the ones between the radius and ulna that allow forearm rotation.
When bones can move along one axis, it indicates the presence of Hinge joint. e.g. Elbows and Knees.
In the Ball and Socket joint, a partial spherical structure is present inside a socket allowing movement in all directions. e.g. hips and arms
As the name suggests Fixed joint allows no movement to occur. e.g Skull
Figure 2: Types of Joints
Important Points to remember in a Human Skeleton:
Bones provide support, protection, movement and perform several other functions.
The bones in the skull (Cranium, Mandible, Maxilla) give protection to the brain.
The long bones such as humerus, radius, ulna, tibia, fibula support the weight of body
The carpals are located in wrist and tarsals are located in ankles. They are examples of short bones.
The bones protecting the spine are called as the vertebral column. Cervical area (top 7 vertebrae), Thoracic (next 12), Lumbar (bottom 5 vertebrae), Sacrum (5 fused or stuck together bones) and Coccyx (the tiny bit at the bottom of the spine).
The sternum and rib cage constitute the chest bones.
Figure 3: Human Skeleton
Some More Points to Remember
Gait of Animals
1. Earthworm:
Does not have bones
Earthworm body is made up of rings
A slimy substances secreted by its body aids movement (NSO)
Figure 4: Detailed Movement in Earthworm
2. Snail:
It has a slimy body, which does not have bones.
The shell of the snail does not help in movement. It has to be carried along.
The foot of the snail is a thick structure and is made up of strong muscles.
A muscular organ called ‘Foot’ helps in locomotion.
Figure 5: A Snail
Cockroach
Belongs to Phylum ArthropodaIts Exoskeleton is hard and stiff.3 pairs of legs help in walking and 4 wings help to flyThe body muscles move the wings when it flies
Fish
Presence of scales on the fish skin reduce frictional dragIt possess a streamlined shape which enhances locomotionCoordination between muscles and tail help the fish to move.Fins aid the movement in the water
Birds
Their forelimbs are modified into wings Presence of hollow and light bones, which reduces weight.Hind limbs help in walking and perchingThey have strong shoulder bones
Snakes
Presence of long backbone and thin muscles.Loops made by its body help in moving forward.Moves fast but not in a straight lineThey cannot move on frictionless surface.
