Protection of Environment
Our planet is a beautiful one, with all the life supporting components on it. Air, water, soil, animals, plants etc. are called natural resources that form our environment. Among many components of environment, human being is the only one who has made environment dirty by polluting its resources i.e. air, water, land etc. Human has disturbed the food chain also.
Some Ways to Protect the Environment
Being the inhabitants of this planet, it’s our duty to protect our environment.
Look at the following picture to understand the method by which we can protect our environment:
Which one of the following is not eco-friendly?
(a) Man cycling 
(b) Girl having leather bag 
(c) Lady throwing wastes in a pit 
(d) House having CFL in place of bulb 
(e) All of these
Answers (b)
Explanation
Leather bag is made from leather obtained by killing animal. Killing of animals for our own benefits would disturb the food chain and the immediate environment. Therefore, option (b) is correct and rest of the options is incorrect.
Anand's mother cooks food by traditional chullah using wood. Whereas Ayush's mother prepares food from biogas. Whom do you think should be treated as friend of our environment.
(a) Anand's mother
(b) Ayush's mother
(c) Both of them
(d) None of them
(e) None of these
Answer: (b)
Explanation
Burning of wood releases lots of smoke in the air which causes air pollution. Inhaling such gases causes many respiratory diseases in the body. Biogas is a safe and clean fuel with respect to environment as it doesn't produces smoke and ash. Therefore, option (b) is correct and rest of the options is incorrect.
Limestone, sandstone and granite are used in the construction of buildings.
Limestone on more heating turns into marble.
75% of earth's land surface is covered by sedimentary rock.
The roots of trees can break rock.
Water keep changing from solid to liquid to gas in nature
Most of the world's water more... 
Atmosphere
Thick envelop of air around the earth is called atmosphere. Air, like other natural resources is very much essential for all kinds of life to survive. We can live without food for many days, without water for few days, but we can't live without air even for few minutes. Air is a mixture of many gases like oxygen, nitrogen, carbon dioxide, argon etc. We inhale oxygen from air. Atmosphere contains 21% oxygen, 78% nitrogen and 1% other gases. Atmosphere extends up to the height of about 120 km above the earth surface.
Layers of Atmosphere
Atmosphere is divided into mainly 4 layers, Thermosphere, Mesosphere, Stratosphere and Troposphere. Atmosphere has an important role to play in cloud formation and precipitation of rain. Ozone layer present in the stratosphere prevents harmful radiations of the Sun to enter earth surface.
Properties of Air
Look at the following picture to understand the properties of air:
Uses of Air
Look at the following picture of the uses of air:
Atmospheric Pressure
Atmosphere exerts pressure on us, known as atmospheric pressure. Atmospheric pressure decreases as we go higher altitudes. This is because thickness of air decreases as we go up.
Air Pollution
The presence of undesirable substances in the atmosphere is threat to the life of all kinds. It is known as air pollution. Undesirable substances are called as contaminants or pollutants.
Look at the following picture to understand the causes of air pollution:
Problems Related to Air Pollution
Air pollution causes many physical and mental problems like respiratory problem, asthma, lung disease, nausea, headache etc. Irritation of skin, allergy are also seen in people living in polluted air zone.
Prevention
We can't stop pollution. But by following certain norms we can minimize it.
By conserving our natural resources sensibly, we can keep our environment clean and green. It will be then a safe and suitable place for the survival of all kinds of life form, whether plants or animals.
Which one of the following layers of atmosphere prevents ultra violet rays to come into the earth surface?
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
(d) Thermosphere
(e) None of these
Answer: (b)
Explanation
Ozone more... 
Rocks and Minerals
Small grains lump together to form rock. Hard surface of the earth constitutes the rock. Rocks are also formed inside the earth from mud and sand under high pressure and heat.
Types of Rocks
There are three types of rocks, namely, igneous rock, sedimentary rock and metamorphic rock. All the rocks are formed in different ways.
Look at the following picture of different types of rocks:
Igneous Rocks
With volcanic eruptions, melted magma comes out on the surface of the earth. When these melted magma cool to solidify, igneous rocks are formed.
Sedimentary Rocks
This rock is formed by sedimentation of material at the surface of the earth and within the bodies of water.
Metamorphic Rocks
Igneous and sedimentary rocks changes to metamorphic rock under heat and high pressure.
Marbles and Slate
Rock is made up of grains or crystals called minerals.
Diamond is a mineral, which is the hardest substance in the world. Other minerals are rubies, emeralds, sapphires, gold, silver etc. which are used in making jewelry and ornaments. Taj Mahal, a beautiful monument in India is made up of marble which is a rock.
Uses of Rocks
Rocks are used in building and construction work. For example : Marble, slate, limestone granite etc. It is used for the making of ornaments and jewelry. For example : Gold silver, diamond. Rubies (minerals).
Which one of the following types of rock is formed when melted magma cool to solidify?
(a) Igneous rock
(b) Metamorphic rock
(c) Sedimentary rock
(d) All of these
(e) None of these
Answer: (a)
Explanation
When melted magma cool to solidify. Igneous rock is formed. Therefore, option (a) is correct and rest of the options is incorrect.
Which one of the following rocks changes into soil?
(a) Igneous rocks
(b) Metamorphic rocks
(c) Sedimentary rocks
(d) All of these
(e) None of these
Answer: (d)
Explanation
All rocks are changed into soil by natural means. Therefore, option (d) is correct and rest of the options is incorrect. 
Environment
Every things in our surrounding, whether living or non living constitute environment. Environment includes everything, that is, vegetation, water, microorganisms, soil, rocks, and atmosphere.
Components of Environment
All the things that exist in the environment has been classified into two groups on the basis of living and non living. Living things are called Biotic components and non-living things are called Abiotic components. Plants, animals, humans, microorganisms etc. are biotic components whereas water, air, soil, rock etc. are abiotic components.
Soil
Soil is a natural resource made up of tiny particles of broken rock, mineral, clay and humus etc. Plants are grown in the top layer of the soil. Soil contains nutrients, water, minerals, humus, and air, which are essential for the growth of the plants. Many living organism like ants, beetles, earth worm, worms, snails etc. make their homes in the soil. Earthworm increases the fertility of the soil by making it porus. Survival on the earth is not possible without soil.
Formation of Soil
Soil is formed by the process of weathering of rocks. Breaking of rocks into smaller particles takes place because of wind, rain and the heat of the sun. Dead plant and animals got mixed up with those broken pieces and results in the formation of soil. It takes thousands of years to break rocks into fine particles. Different types of soils are found in different places of India.
Layers of Soil
The earth is made up of three layers of soil:
Top Soil
Sub Soil
Bed Rock
Top Soil
This uppermost layer is rich in minerals and humus. Humus makes the soil fertile. This layer is soft and can retain water. Hence most plants are grown in this layer.
It also provides habitat to many organisms like earth worm, rat, snakes, beetles etc. This layer is dark in colour.
Sub Soil
It lies below top soil, and is comparatively harder and contains less amount of humus and other nutrients. It is red or grey in colour.
Bed Rock
It lies below subsoil and is soft porus on the upper side and hard non porus in the inner side. It can't be dig manually.
Look at the following picture of the layers of rock:
Types of Soil
Mainly three types of soil are found:
Sandy Soil
Clayey Soil
Loamy Soil
Sandy Soil
It is made up of more... 
Sensory System
We can see beautiful scene, hear pleasant sound, smell good things, taste delicious food, feel softness with the help of our sense organs eyes, ear, nose tongue and skin respectively. These sense organs constitute sensory system in our body.
These sense organs receive stimulus from the surroundings and send these messages to the brain through nerves for interpretation. Our brain respond to the stimuli with the help of these sense organs. Sense organs are called as receptor of information. For example, if we see snake coming towards us, eyes send this message to brain, brain interprets the situation and instruct the body to run. These process; occurs in a fraction of second.
Sense organs help in receiving stimuli from the surrounding and respond accordingly.
Problems in Sense Organs
A person affected of night blindness can't see in dark. A person affected of colour blindness can't differentiate between colours.
Visibility becomes less in cataract which generally occurs in old age.
Person can't hear at all (deaf) or can hear only loud sound if there is problem in ear.
How to Keep Fit
Our sensory organs should be cleaned all the time. Eyes should be washed with clean water. Food rich in vitamin A is good for eyes. We should eat healthy and balanced diet. We should not play music at very loud sound.
Match the following
P. 
P. Tasting
Q. 
Q. Smelling
R. 
R. Seeing
S. 
S. Feeling
T. 
T. Hearing
(a) P-R, Q-Q, R-P, S-S, T-T
(b) P-Q, R-S, S-T, T-P, Q-R
(c) P-P, Q-Q, R-R, S-S, T-T
(d) P-T, Q-S, R-P, S-Q, T-R
(e) None of these
Answer: (a)
Explanation
Eyes to see, nose to smell, tongue to taste, ear for hearing, and skin to feel. Therefore, option (a) is correct and rest of the options is incorrect.
more... 
Nervous System
Every day our body performs a lot of functions. Brain is at the center of all the activities. Brain only tells us what to do or what not to do. For example, in the process of walking brain just order the related organ to move. Muscles which are involved in waking get active and perform walking.
Coordination and Cooperation between Brain and Body
Our eyes see a rose flower. This message reaches brain through a network of cells called nerves. Brain interprets the information and recognise that it is a rose flower. The nerves act like messenger. Spinal cord connects all the parts of the body to the brain. Skull protects brain and backbone protects spinal cord from injury. The brain, spinal cord and nerves constitutes nervous system.
When finger touch the hot plate, receptor receives the information and send it to brain through nerves. Brain analyze the situation and order the related muscles to remove the finger. This all happens in fraction of a second. This is how body performs function under the guidance of the brain.
Stimulus --> Message --> Nerves --> Brain --> Nerves --> Fingers to remove
Nervous Problems
Headache is common in people which are generally not very serious. Migraine is a severe headache that can be dangerous. Development of tumour in the brain is a very dangerous problems, which are removed surgically.
How to Prevent the Nervous Problems
We should protect our brain from any injury. Wearing helmet is a protective device while riding a bike.
Which one of the following organs sends message to the brain from the receptor site.
(a) Heart
(b) Lungs
(c) Skin
(d) Nerves
(e) Finger
Answer: (d)
Explanation
Nerves receives messages from the receptor as an electrical impulses and carries it to the brain. Therefore, option (d) is correct and rest of the options is incorrect.
Consider the following statements:
Statement 1: Brain is a part of nervous system
Statement 2: Brain is a part of muscular system
Which one of the following is correct about the above statements?
(a) Statement 1 is true and 2 is false
(b) Statement 1 is false and 2 is true
(c) Both statements are false
(d) Both statements are true
(e) None of these
Answer: (a)
Explanation
Brain is a part of nervous system. Therefore, option (a) is correct and rest of the options is incorrect.
Circulatory System
Blood more... 
Muscular System
Muscles constitute more than half of the body. Muscles are attached to the bones and help in providing movements of the body. All the muscles together form the muscular system of the body. We show happiness, sadness, anger etc., on our face with the help of muscles. Legs and arms muscles get shorten and lengthen to bring movements.
Muscular Problems
Muscle cramp develops during hard exercise which is very painful. Break in muscle is called muscle fracture.
How to Keep Muscular System Fit:
Using and exercising of muscles makes it fit and healthy.
Bending and stretching of muscles keep it active and healthy
Walking or cycling is good for muscles.
Muscular system is made up of:
(a) Muscles
(b) Bones
(c) Cartilages
(d) Joints
(e) All of these
Answer: (a)
Explanation
Muscular system is made up of muscles. Therefore, option (a) is correct and rest of the options is incorrect.
Which one of the following activities is done by muscles?
(a) Walking
(b) Swimming
(c) Running
(d) Jumping
(f} All of these
Answer: (e)
Explanation
Muscles support the body movement. Therefore, option (e) is correct and rest of the options is incorrect. 
Skeletal System
All the bones in the body together form skeletal system. Bones protect the soft organs of the body. Skeletal system is the framework of the bones. It gives proper shape and form to the body. Femur bone is the longest bone and the smallest bone of the human body are present in ear. There are 206 bones in the body. Joints fastened two or more bones together. Joints allow body to move in a particular direction.
Skeletal Problems
Too much pressure on bones and joints can break it, which we call fracture. If the blood supply to the bones is blocked, then it causes the skeletal disorder. Bones can also be affected by virus.
How to Prevent Skeletal Problems
We can make our bones and joints healthy by doing exercise, taking healthy diet.
We should drink milk and eat dairy products rich in calcium to build up strong bones and joints.
The bone present inside the head is called:
(a) Skull
(b) Spine
(c) Vertebral column
(d) Rib cage
(e) None of these
Answer: (a)
Explanation
Skull is an immovable bone, spine lies below it, rib cage is the cage of bone in the chest, and vertebral column lies at the back. Therefore, option (a) is correct and rest of the options is incorrect.
How many bones are present in a human body?
(a) 200
(b) 150
(c) 205
(d) 206
(e) 350
Answer: (d)
Explanation
The human skeleton has a total of 206 bones. Number of bones are more in an infant which fuses and becomes 206 as it grows older. Therefore, option (d) is correct and rest of the options is incorrect. 
Respiratory System
We take in air mostly through our nose, which is then passes through the wind pipe into the lungs. The air we take in is called inhaled air. It is rich in oxygen. And the air, which is expelled from the lungs outside of our body is called exhaled air, which is rich in carbon dioxide. This whole process of inhaling and exhaling of air is called respiration and the organs involved in the process is called as respiratory organs. Breathing system can be simply represented as:
Air from outside ---> Nose -----> Wind pipe ------> Lungs
Respiratory Problems
Coughs and sneezes are respiratory problems. Sneezing is caused when tiny unwanted particles enters into our nose. Asthma and allergy are also respiratory problems.
How to Prevent Respiratory Problems
We should take in fresh oxygen. Exercise is also essential to keep our respiratory system healthy.
Which one of the following organs can take in oxygen from the air?
(a) 
(b) 
(c) 
(d) 
(e) Both (a) and (c)
Answer: (a)
Explanation
Generally air is taken in through the nose. Therefore, option (a) is correct and rest of the options is incorrect.
Which one of the following is not a part of respiratory system?
(a) Ear
(b) Nose
(c) Windpipe
(d) Lungs
(e) None of these
Answer: (a)
Explanation
Ear is not a part of the respiratory system. Therefore, option (a) is correct and rest of the options is incorrect. 
Organs of Our Body
Our body is made up of cells. Cells are the smallest unit of life. Cells, which are similar in structure and function, group together and perform a common function. These group of cells are called tissues. Accordingly, many similar tissues combine together and perform a common function, called organ. Eyes, nose, heart, brain, lungs, skin etc. are different organs of the body.
Eye Brain Nose Heart Lungs
These organs perform different functions. For example, we see with our eyes, smell with our nose, heart pumps blood to all the parts of the body whereas lungs help in taking in oxygen and giving out of carbon dioxide.
Our body is a living thing and hence it performs functions like breathing, feeding, growth, reproduction, excretion and respond to changes in the environment etc.
These processes are not so simple and it can't be performed by a single organ rather many organs are involved in each process. These groups of organs are called organ system. Human body is a complex organism comprising of many organ system. Food, which we take, has to pass through a long process till are digested and absorbed by the blood. Passage of food through the body is depicted by the flow chart given below.
Look at the following chart of the flow of food in our body:
Digestive Diseases
Uneasiness and indigestion causes due to overeating or not chewing food properly.
Diarrhea and vomiting occurs when germs or bacteria enter the body through infected food.
How to Prevent Digestive Disease
We should eat healthy food, i.e. lots of green leafy vegetables and fruits. Food should not be eaten fast, rather it should be chewed properly. We should also drink plenty of water for proper digestion of food.
Which one of the following is an organ of human body?
(a) Heart
(b) more... 
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