16/SEPTEMBER/2021
REVISION
CHAPTER 6 : INSECTS
Assignment:- Complete the following in your Science-OCB.
14/SEPTEMBER/2021
REVISION
CHAPTER 6 : INSECTS
Now watch this video for your better understanding:-
Insects are usually the small creatures that we often see in our surroundings. Most of the insects have wings which are not very muscular. Thus, there is a limitation for their flight. Some of the common insects which we come across in our daily lives are ants, beetles, bees, flies, mosquitoes and cockroaches.
PARTS OF AN INSECTS BODY
Most of the insects have six legs. The body of an adult insect is divided into three parts : head, thorax and abdomen. Insects have antennae on their head. This antennae is a thin whip like structure which helps the insect to smell and feel. Most of the insects have wings. These wings do not have strong flight muscles, hence they fly only for short intervals and short distance. Insects have a hard outer covering, called chitin on their body.
A cockroach has a set of antennae which helps it to locate its food, helps in movement.
Insects like butterfly have a long sucking tube in their mouth called proboscis. A butterfly uses this tube to suck nectar from a flower.
Most insects have two pairs of wings. In certain cases there is only one pair of wings as that of housefly.
Some insects don’t have wings. Ants and louse are wingless insects.
Insects breathe through tiny air holes called spiracles present on the body surface.
Small creatures that look like insects but are not insects.
There are many creatures which look like insects but they are not actually insects. Spider, scorpion, centipede, millipede, snail, earthworm etc. are such creatures commonly seen around us. But these are not put under the category of insects.
SOCIAL INSECTS
Some insects live together in colonies or communities. They live in societies like man. They are called social insects. Ants and bees are social insects.
The social life of such insects is very well-organised. Each member of the community has definite work to do. Like us, ants divide the work of the colony among them.
Queen ant : Queen ant spends all her life in laying eggs.
Male ants : A few winged male ants help the queen ants in laying eggs.
Female worker ants : Thousands of wingless female worker ants gather food, take care of eggs and maintain the colony.
Life cycle of a Butterfly
A butterfly completes its life cycle in four stages : egg, larva (caterpillar), pupa and adult.
• Butterflies lay eggs on plant leaves.
• Eggs hatch to produce larva. It is also called caterpillar. It is very different from the adult butterfly.
• Larva/caterpillar moults to form pupa.
• Pupa changes to adult butterfly.
Useful insects :
Some insects are useful to us. They help us in many ways.
1. Honeybees collect nectar from flowers. They store it as honey. The beehive is made of wax, thus, we can say that wax is also produced by bees.
2. Some insects like butterflies, bees etc. help is pollination.
3. We get silk from the pupa of silk moth.
4. Many insects act as useful scavengers. They eat-up dead animals and plants.
Harmful insects :
1. Insects like grasshopper, beetle, locust etc. damage our crops, vegetables and fruits. They are called pests.
2. Mosquitoes spread diseases like malaria, filaria, yellow fever etc.
3. White ants, silver fish, cloth moths feed on the wood, paper and clothes in our homes. Thus, they cause damage to our household things.
Simple steps to get rid of unwanted insects :
1. Hair should be kept clean by washing and regular combing. This keeps hair healthy and free of head louse.
2. Moth balls or dried neem leaves should be kept with silk or woollen clothes. They keep insets away.
3. We should spray chemicals like D.D.T. and other insecticides in the places where insects live
Assignment:- Read chapter-6 carefully
09/SEPTEMBER/2021
CHAPTER 5 : BIRDS AND THEIR CLAWS
Assignment:- Complete the following in your Science-OCB.
07/SEPTEMBER/2021
REVISION
CHAPTER 5 : BIRDS AND THEIR CLAWS
Now watch this video for your better understanding:-
How do we walk? We have feet to stand and to walk. The birds normally fly but sometimes they stand on their claws to eat grains or the food stuff they like. They hold the branches with their claws and even protect themselves with their claws.
The claws of birds help them in number of ways :
• Help the birds to hold the branch.
• Help the birds to hold their prey.
• Help the birds to climb up the trees.
• Help the birds to walk and run on ground.
• Help the birds to scratch for seeds and worms.
Different birds have different types of claws. It actually depends on the functions which a bird has to perform. The functions can vary with food habits, type of nests it makes and the type of locomotion or movement. The main function of feet and claws is protecting themselves from their enemies and moving about. Depending upon the structure of claws, the birds can be classified as:
• Perching birds
• Scratching birds
• Climbing birds
• Wading birds
• Preying birds
• Swimming birds
1. Perching Birds
Birds like crow, sparrow etc. perch and hop on the branches. They have three toes in front and one at the back. Such toes help them to hold the branches firmly.
They hop on the ground and can even sleep while perching.
2. Climbing Birds
Birds like woodpecker and parrots have two toes pointing upwards and two downwards. Such toes help them to climb up the trees.
3. Preying Birds
Birds like eagles, hawks etc. have strong and sharp claws to catch and hold their prey. The claws of preying birds are called talons.
4. Scratching Birds
Birds like hens use their claws to scratch the earth for seeds and worms. Such birds are called scratching birds. They have sharp and hard claws with three toes in front and one at the back. These birds can both walk and run on the ground.
5. Wading Birds
Birds like cranes, herons walk in shallow water especially in search of food. Such birds are called wading birds. These birds have long legs and wide spreading toes. These toes keep the feet from sinking in the soft mud.
6. Swimming Birds or Aquatic Birds
Birds like ducks and swans swim in water. Such birds are called swimming or aquatic birds. These birds have webbed feet. These feet help them to paddle and push water while swimming.
NESTS OF BIRDS
As we all live in a house. Birds live in a nest. Nest is the dwelling place of a bird. They build their nest to lay eggs, keep their young ones safe and warm.
Different birds have different type of nests. The nests differ in the shape, size and nature of material used for building the nest.
• Bulbul’s Nest
Bulbuls build their nests in hedges and bushes with the help of grass. The nests look like a deep cup.
• Tailor Bird’s Nest
A weaver bird uses its beak to sew big leaves together with the help of thread, wool etc., to make a cosy nest.
• Woodpecker’s Nest
Woodpecker makes a hole into the trunk of a tree. This hole is used as a nest.
• Vulture’s Nest
Vultures use sticks to make big nests in tall trees.
• Owl’s Nest
Owls make their nest in the hollow of a tree. The nest is lined with feathers and grass.
Assignment:- Read chapter -5 carefully and Do Page No. 49 and 52 in the text book.
02/SEPTEMBER/2021
CHAPTER 8: WATER
Assignment:- Complete the following in your Science-OCB.
31/AUGUST/2021
CHAPTER 8: WATER
Now watch these videos for your better understanding:-
Water Purification at Small level
The water brought to the houses may sometimes carry germs in the way. These germs may be removed by:
Boiling and Straining : Water may be boiled and then filtered with the help of a clean cloth.
Storage : The purified water should be stored in clean containers with a lid.
Chlorine Tablets
Chlorine tablets are used to kill the germs at the small level. It is simply added to drinking water, then kept for sometimes before consuming.
Hard and Soft Water
Soft Water : Water which forms lather with soap easily is known as soft water.
Example : Rainwater and distilled water.
Hard Water : Water which does not form lather with soap is known as hard water.
Example : Well water and spring water.
Water Contain Dissolved Gases
• Dissolved gases in water provide taste to the water.
• Oxygen dissolved in water helps in the respiration and survival of aquatic life.
• Carbon dioxide dissolved in water helps in photosynthesis of aquatic plants.
SOLUBILITY AND SOLUTION
Water is known as universal solvent because it can dissolve all kinds of solids, liquids or gases to little or more extent. According to the solubility, the substances may be classified as soluble or insoluble substances.
• The substances which dissolve rapidly in water are called soluble substances.
Examples : Common salt and sugar.
• The substances which dissolve very little or do not seem to dissolve are known as insoluble substances.
Examples : Mud and sand.
SOLUTION
The mixture formed by dissolving a soluble substance in water is known as solution.
Common Terms used in the formation of a Solution
1. Solvent : A liquid which dissolves other substances in it is called solvent. For example, common salt dissolves in water
and hence water is a solvent.
2. Solute : A substance which dissolves in a liquid is called solute. Example : In the above example common salt is the
solute.
3. Unsaturated Solution : A solution which has less amount of solute is known as unsaturated solution.
4. Saturated Solution : A solution which has large amount of solute is known as saturated solution.
Conditions which enhance the formation of a solution :
1. Solute and solvent must be capable of mixing.
2. High temperature enhances the formation of a solution.
3. Stirring helps in quick formation of the solution.
4. Solute should be in the form of a fine powder, as it helps in the formation of solution quickly.
IMPURITIES AND ITS REMOVAL
There are two types of impurities soluble and insoluble.
Both these impurities are present in water. Thus the removal of these impurities become important.
Some methods of removing insoluble impurities
1. Filtration The separation of insoluble impurities with the help of filter paper or muslin cloth is known as filtration.
Filtrate : The clear liquid which passes through the filter paper is known as filtrate.
Residue : The solid impurity left on the filter paper is known as residue.
2. Sedimentation and Decantation
The process of settling down of heavy impurities is known as sedimentation and then removing the clear liquid from the top is known as decantation.
Step I: The impure water is allowed to stand for sometime.
Step II: The impurities settle down at the bottom of the container as sediments.
Step III: The clean water poured out into a separate container is known as decantation.
Removal of soluble impurities
Soluble impurities are very finely mixed in water. Hence, their removal becomes bit difficult. These impurities can be removed by evaporation or by distillation.
Assignment:- Read chapter-8.
26/AUGUST/2021
CHAPTER 8: WATER
Now watch this video for your better understanding:-
Water plays a key role in carrying out important activities like drinking, cooking, bathing, irrigation etc. Hence, life is possible on the earth due to the presence of water. Nearly three-fourth of the earth’s surface is covered with water. It is present in all living things.
OCCURRENCE OF WATER
Water is present almost in all natural things like plants, animals, rocks and air. In the solid state, it exists as snow in snow covered mountains. It is present in rocks and minerals as water of crystallisation and as water vapours in air.
Surface and underground water
Surface water : Water which is present on the surface of the earth is called surface water.
Example : Rainwater, sea water.
Underground water : The water which collects over the hard rock below the earth is called underground water.
Example : Well water, spring water.
WATER CYCLE
Circulation of water from the earth’s surface to the atmosphere and back to the earth is called the water cycle.
POTABLE WATER
Water which is clean and pure and fit for human consumption is known as potable water.
Need for Potable Water
The water which is present in lakes, rivers and as underground water; can only be used for human consumption. Thus, there exist an intense need for potable water.
Characteristics of Drinking Water :
It should be :
(i) Colourless
(ii) Odourless
(iii) Free from suspended impurities
(iv) Free from bacteria and germs
(v) Free from harmful compounds
PURIFICATION OF WATER
The impure water has to undergo series of steps for the process of purification.
Step I : Pumping
Water from rivers, lakes is fed into pumping station where it is pumped into big reservoirs.
Step II : Sedimentation
Water is collected in reservoirs. Heavy particles settle down in this tank. Chemicals like alum are added to speed the process of sedimentation.
Step III : Filtration
After sedimentation, the water is filtered through a clean sandbed to remove the finer suspended particles.
Step IV : Chlorination
Water is then disinfected with a very small quantity of chlorine gas to kill bacteria.
Assignment:- Read chapter-8 page No. 76 to 78.
24/AUGUST/2021
REVISION
CHAPTER 4: BIRDS AND THEIR BEAKS
Assignment:- Complete the following in your Science-OCB.
10/AUGUST/2021
REVISION
CHAPTER 4: BIRDS AND THEIR BEAKS
NOW WATCH THIS VIDEO FOR YOUR BETTER UNDERSTANDING:-
Birds are beautiful creatures different from plants and animals. They are the animals with feathers. There are about 8600 species of birds.
Birds have light bodies. They have well formed wings attached to their body with the help of strong muscles. A bird flaps its wings in both directions i.e., upward and downward direction to fly.
The upward movement of wings is known as upstroke.
The downward movement of wings is known as downstroke.
FEATHERS
A bird’s body is covered with feathers. Each bird has different kinds of feathers.
1. Body feathers : Feathers which are small and of different colours and cover the body of birds are known as body feathers.
2. Down feathers : Down feathers are fluffy and soft. They keep the bird warm.
3. Flight feathers : Flight feathers are long and found mainly on the wings. They help the bird to fly.
All BIRDS CANNOT FLY
Some birds like ostrich and penguin cannot fly because they are too heavy to fly.
Aquatic Birds
Some birds can swim in water. Such birds are known as aquatic birds.
Features of Aquatic Birds
Aquatic birds have:
1. Oil-glands which keep their feathers water proof.
2. They have webbed feet which help them to swim in water.
Birds help in dispersal of seeds. They support out ecosystem and helps it to function smoothly.
BEAKS OF BIRDS
As we have mouth to eat, birds have beaks. The beak of bird is designed according to the food it eats. Thus, the shape of beak vary from bird to bird. Some birds use their beak to protect themselves from their enemies.
Types of Beaks
1. Small, hard and pointed beaks :
Birds like sparrow and pigeon which eat grains, seed and crack nuts have small, hard and pointed beaks.
2. Curved beaks :
Birds like parakeet have curved beak. This curved beak helps it to crack nuts and hard fruits. It also helps a parakeet to climb.
3. Strong, sharp and hooked beaks :
Birds like eagles, vultures, kites, owls and hawks have strong, sharp and hooked beaks for tearing the flesh of small birds.
4. Broad and flat beak :
Birds like ducks have broad and flat beaks. Such beaks help them to dig in soft mud and find worms for its food.
5. Strong and chisel-shaped beak :
Birds like woodpecker have strong and chisel shaped beak. It helps the woodpecker to make holes in tree trunk and catch insects for its food.
6. Broad and short beak :
Birds like swallow have broad and short beak. Its beak is sticky from inside. It has a very different way of feeding. It moves round and round in air with its beak open. Tiny flying insects get struck inside their beaks.
7. Broad, long and pointed beak :
Birds like kingfisher and storks have broad, long and pointed beaks to catch fish from rivers and ponds.
Assignment:- Read Chapter-4 and Revise all exercises.
05/AUGUST/2021
CHAPTER 7: STATES OF MATTER
Assignment:- Complete the following in your Science-OCB.
03/AUGUST/2021
CHAPTER 7: STATES OF MATTER
Now watch this video for your better understanding:-
Whatever is present around us is known as matter. The table, chair, blackboard, chalk, duster, bags, air, water etc. can be called as matter.
• In other words we can see and feel matter by our senses.
• Matter is anything which occupies space, has weight and can be perceived by our senses.
A school bag containing books is a matter.
Composition of Matter
• Matter is just like a closed sac of grains.
• When it is opened, it gives you wheat grains which are like molecules.
• When it is grounded, it gives you small flour particles which are like atoms.
States of Matter
Solid State
• If molecules are present close to each other, then it is solid state.
• Solids have a definite shape.
Liquid State
• If molecules are present away from each other, then it is liquid state.
• Liquids take the shape of the container.
Gaseous State
• If molecules are present very far away from each other, then it is gaseous state.
• Gases do not have any definite shape.
Can states of matter be changed?
• When some solids are heated, they can change into a liquid or a gas.
• Some gases when cooled, change into liquids and solids.
Assignment:- Read chapter- 7 and learn underlined words.29/JULY/2021
REVISION
CHAPTER 3: PLANTS
27/JULY/2021
REVISION
CHAPTER 3: PLANTS
Now watch this video for your better
understanding:-
Plants are living organisms. They are fixed to the soil. Plants also have many body parts. There are different kinds of plants. These plants differ in height, structure and looks. Most of the plants grow in soil. Hence, we can divide the body of a plant into two main parts : root and shoot.
Similarly, the different parts of a plant perform different functions. Each plant part has an important task to do in the life of the plant.
Roots fix the plant to soil and shoot contain stem which bears fruits, flowers and buds.
ROOT
The part of the plant which remains under the ground is called the root.
Functions of Roots
• It holds the plant firmly to the soil.
• It helps to take up water and minerals from the soil.
• Some roots store the food and are used for eating.
Types of Roots
Roots are mainly of two types:
• Fibrous roots
• Tap roots
Fibrous Root System—When several tiny roots grow from the end of the stem, it is called fibrous root system.
Examples : Wheat and rice.
Tap Root System—When a single main root grows from the end of stem and many small roots grow from it, it is called a tap root system.
Examples : Cotton and mustard.
STEM
Stem is the main part of shoot. It bears leaves, buds and flowers. The main stem which is large and thick is called the trunk and the other thinner stems are called branches.
Functions of Stem
• The stem holds up leaves and flowers.
• It carries water to all parts of the plant.
• Hard stems support the plant.
• Weak and green stems prepare food for plant.
• Some stems store the food and are used for eating.
Types of Stem
Stem is broadly classified into three categories:
LEAF
Leaves are usually green coloured structures attached to the stem. The leaf absorbs maximum sunlight due to its flat surface.
Functions of Leaf
• Green leaves help the plant to prepare its food.
• Leaves contain stomata. It helps the leaves to breathe.
• Some leaves become thick and fleshy and store food. Such leaves can be used for eating.
FLOWERS
Flowers are the colourful structures attached to stem. They make the plant look attractive.
Functions of Flowers
• Flowers help in the reproduction of plant.
• Many flowers like rose and jasmine yield perfumes.
• Many flowers produce a sweet liquid called nectar.
• Some flowers change into fruit.
FRUITS
Fruits are the sweet edible part of a plant. Fruits also contain a sweet fragrance. Not only human beings but many birds and animals also eat fruits. Fruits are formed from flowers. They contain seeds.
The number of seeds are different in different fruits.
Functions of Fruits
• Fruits store the food material.
• Fruit contain the seeds which when sown give rise to a new plant.
Seeds
Seeds are the hard structures present in a fruit. Seed contain a tiny baby plant in it. This baby plant in the seed is protected by a seed coat.
Types of Seeds
Edible seeds: Seeds of some plants can be eaten. Such seeds are called edible seeds. e.g., Wheat and gram.
Non-edible seeds: Seeds of some plants cannot be eaten. Such seeds are called non-edible seeds. e.g., Orange and apple seeds. Seed is protected by a hard layer. When it is sown, the seed coat burst open and a baby plant emerge out. This baby plant grows into a healthy plant on receiving proper amount of sunlight, air, water and minerals from soil.
Similarly, the different parts of a plant perform different functions. Each plant part has an important task to do in the life of the plant.
Roots fix the plant to soil and shoot contain stem which bears fruits, flowers and buds.
ROOT
The part of the plant which remains under the ground is called the root.
Functions of Roots
• It holds the plant firmly to the soil.
• It helps to take up water and minerals from the soil.
• Some roots store the food and are used for eating.
Types of Roots
Roots are mainly of two types:
• Fibrous roots
• Tap roots
Fibrous Root System—When several tiny roots grow from the end of the stem, it is called fibrous root system.
Examples : Wheat and rice.
Tap Root System—When a single main root grows from the end of stem and many small roots grow from it, it is called a tap root system.
Examples : Cotton and mustard.
STEM
Stem is the main part of shoot. It bears leaves, buds and flowers. The main stem which is large and thick is called the trunk and the other thinner stems are called branches.
Functions of Stem
• The stem holds up leaves and flowers.
• It carries water to all parts of the plant.
• Hard stems support the plant.
• Weak and green stems prepare food for plant.
• Some stems store the food and are used for eating.
Types of Stem
Stem is broadly classified into three categories:
LEAF
Leaves are usually green coloured structures attached to the stem. The leaf absorbs maximum sunlight due to its flat surface.
Functions of Leaf
• Green leaves help the plant to prepare its food.
• Leaves contain stomata. It helps the leaves to breathe.
• Some leaves become thick and fleshy and store food. Such leaves can be used for eating.
FLOWERS
Flowers are the colourful structures attached to stem. They make the plant look attractive.
Functions of Flowers
• Flowers help in the reproduction of plant.
• Many flowers like rose and jasmine yield perfumes.
• Many flowers produce a sweet liquid called nectar.
• Some flowers change into fruit.
FRUITS
Fruits are the sweet edible part of a plant. Fruits also contain a sweet fragrance. Not only human beings but many birds and animals also eat fruits. Fruits are formed from flowers. They contain seeds.
The number of seeds are different in different fruits.
Functions of Fruits
• Fruits store the food material.
• Fruit contain the seeds which when sown give rise to a new plant.
Seeds
Seeds are the hard structures present in a fruit. Seed contain a tiny baby plant in it. This baby plant in the seed is protected by a seed coat.
Types of Seeds
Edible seeds: Seeds of some plants can be eaten. Such seeds are called edible seeds. e.g., Wheat and gram.
Non-edible seeds: Seeds of some plants cannot be eaten. Such seeds are called non-edible seeds. e.g., Orange and apple seeds. Seed is protected by a hard layer. When it is sown, the seed coat burst open and a baby plant emerge out. This baby plant grows into a healthy plant on receiving proper amount of sunlight, air, water and minerals from soil.
Assignment :- Read Chapter -3 Carefully and learn underlined words.
22/JULY/2021
REVISION
CHAPTER 2: THE RESPIRATORY SYSTEM
Assignment:- Complete the following in your Science-OCB.
20/JULY/2021
REVISION
CHAPTER 2: THE RESPIRATORY SYSTEM
Now watch this video for your better understanding:-
BREATHING
The process during which air rich in oxygen is taken in and air rich in water vapours and carbon dioxide is given out is known as breathing.
INHALATION
The process of taking in of air is known as inhalation.
EXHALATION
The process of giving out of air is known as exhalation. Breathing is a continuous process and occurs throughout the life of all organisms.
RESPIRATION
The process of breaking down the complex food substances with the help of oxygen and releasing energy is known as respiration.
Why do we respire ?
As all machines need energy to work. Similarly, our body also needs energy for its various activities. This energy is obtained by respiration of food we eat. Respiration takes place inside the body cells.
THE RESPIRATORY SYSTEM
The organs that help in respiration together form the respiratory system. Thus, the various parts of respiratory system includes nose, nasal passage, windpipe and lungs.
Nose and Nasal passage
We breathe through nose or nostrils. The nostrils contain hair. These hair trap dust particles and germs and send clean air for respiration. Thus, we should always
breathe through our nose.
Windpipe
The air from the nasal passage reaches the lungs through windpipe and then divides into two bronchi and then enter into the two lungs.
LUNGS
Lungs are the main respiratory organs in our body. They are a pair of spongy, elastic and bag like structures. When we breathe in, the lungs gets filled with fresh air. This air is taken by blood to all parts of the body and the used air is then given back to lungs.
The air we inhale contains lot of oxygen which is taken by lungs. In our body, the percentage of oxygen decrease because our body takes oxygen for respiration and gives out carbon dioxide. This gas is then given out of the body.
AIR POLLUTION
The mixing of harmful components in air is known as air pollution. Air pollution effects our respiratory system and cause number of diseases. The germs present in air enter into the respiratory tract and multiply causing various allergic diseases.
Sneezing : When we inhale, the germs are trapped by the hairs present inside the nose. Sometimes, these particles are not trapped and cause irritation. Thus, sneezing occurs to throw these particles out.
Coughing : If unwanted particles enter the respiratory tract, then coughing occurs to throw these particles out.
Asthma : The breathing difficulty that occurs due to an allergic disorder is known as asthma.
Other than these, polluted air cause common cold, headache, dizziness, inflammation of lungs and bronchitis. Common cold results from the germs that attack our body resulting in fever, nasal discharge, headache and reddening of eyes.
Precautions
1. Eating healthy food keeps our body healthy and prevents us from diseases.
2. Common cold is a communicable disease. Thus, keep a handkerchief infront of your nose while sneezing.
3. Take personal care of health and hygiene.
4. In case of severe cold, visit doctor.
How to ensure healthy breathing ?
1. Morning walk is very helpful because the air is clean and fresh.
2. Alpha breathing process increases the capacity of lungs.
3. People during yoga maintain good posture which helps to breathe properly.
4. Too much of fatty foods reduce the capacity of breathing and in turn leads to obesity.
Thus, healthy food and good posture helps in healthy breathing.
The process during which air rich in oxygen is taken in and air rich in water vapours and carbon dioxide is given out is known as breathing.
INHALATION
The process of taking in of air is known as inhalation.
EXHALATION
The process of giving out of air is known as exhalation. Breathing is a continuous process and occurs throughout the life of all organisms.
RESPIRATION
The process of breaking down the complex food substances with the help of oxygen and releasing energy is known as respiration.
Why do we respire ?
As all machines need energy to work. Similarly, our body also needs energy for its various activities. This energy is obtained by respiration of food we eat. Respiration takes place inside the body cells.
THE RESPIRATORY SYSTEM
The organs that help in respiration together form the respiratory system. Thus, the various parts of respiratory system includes nose, nasal passage, windpipe and lungs.
Nose and Nasal passage
We breathe through nose or nostrils. The nostrils contain hair. These hair trap dust particles and germs and send clean air for respiration. Thus, we should always
breathe through our nose.
Windpipe
The air from the nasal passage reaches the lungs through windpipe and then divides into two bronchi and then enter into the two lungs.
LUNGS
Lungs are the main respiratory organs in our body. They are a pair of spongy, elastic and bag like structures. When we breathe in, the lungs gets filled with fresh air. This air is taken by blood to all parts of the body and the used air is then given back to lungs.
The air we inhale contains lot of oxygen which is taken by lungs. In our body, the percentage of oxygen decrease because our body takes oxygen for respiration and gives out carbon dioxide. This gas is then given out of the body.
AIR POLLUTION
The mixing of harmful components in air is known as air pollution. Air pollution effects our respiratory system and cause number of diseases. The germs present in air enter into the respiratory tract and multiply causing various allergic diseases.
Sneezing : When we inhale, the germs are trapped by the hairs present inside the nose. Sometimes, these particles are not trapped and cause irritation. Thus, sneezing occurs to throw these particles out.
Coughing : If unwanted particles enter the respiratory tract, then coughing occurs to throw these particles out.
Asthma : The breathing difficulty that occurs due to an allergic disorder is known as asthma.
Other than these, polluted air cause common cold, headache, dizziness, inflammation of lungs and bronchitis. Common cold results from the germs that attack our body resulting in fever, nasal discharge, headache and reddening of eyes.
Precautions
1. Eating healthy food keeps our body healthy and prevents us from diseases.
2. Common cold is a communicable disease. Thus, keep a handkerchief infront of your nose while sneezing.
3. Take personal care of health and hygiene.
4. In case of severe cold, visit doctor.
How to ensure healthy breathing ?
1. Morning walk is very helpful because the air is clean and fresh.
2. Alpha breathing process increases the capacity of lungs.
3. People during yoga maintain good posture which helps to breathe properly.
4. Too much of fatty foods reduce the capacity of breathing and in turn leads to obesity.
Thus, healthy food and good posture helps in healthy breathing.
Assignment:- Read chapter-2 carefully and learn all underlined words.
15/JULY/2021
CHAPTER 6: lNSECTS
Assignment:- Complete the following in your Science-OCB.
13/JULY/2021
CHAPTER 6: lNSECTS
08/JULY/2021
CHAPTER 6: lNSECTS
Now watch this video for your better understanding:-
Insects are usually the small creatures that we often see in our surroundings. Most of the insects have wings which are not very muscular. Thus, there is a limitation for their flight. Some of the common insects which we come across in our daily lives are ants, beetles, bees, flies, mosquitoes and cockroaches.
PARTS OF AN INSECTS BODY
Most of the insects have six legs. The body of an adult insect is divided into three parts : head, thorax and abdomen. Insects have antennae on their head. This antennae is a thin whip like structure which helps the insect to smell and feel. Most of the insects have wings. These wings do not have strong flight muscles, hence they fly only for short intervals and short distance. Insects have a hard outer covering, called chitin on their body.
A cockroach has a set of antennae which helps it to locate its food, helps in movement.
Insects like butterfly have a long sucking tube in their mouth called proboscis. A butterfly uses this tube to suck nectar from a flower.
Most insects have two pairs of wings. In certain cases there is only one pair of wings as that of housefly.
Some insects don’t have wings. Ants and louse are wingless insects.
Insects breathe through tiny air holes called spiracles present on the body surface.
Small creatures that look like insects but are not insects.
There are many creatures which look like insects but they are not actually insects. Spider, scorpion, centipede, millipede, snail, earthworm etc. are such creatures commonly seen around us. But these are not put under the category of insects.
SOCIAL INSECTS
Some insects live together in colonies or communities. They live in societies like man. They are called social insects. Ants and bees are social insects.
The social life of such insects is very well-organised. Each member of the community has definite work to do. Like us, ants divide the work of the colony among them.
Queen ant : Queen ant spends all her life in laying eggs.
Male ants : A few winged male ants help the queen ants in laying eggs.
Female worker ants : Thousands of wingless female worker ants gather food, take care of eggs and maintain the colony.
Life cycle of a Butterfly
A butterfly completes its life cycle in four stages : egg, larva (caterpillar), pupa and adult.
• Butterflies lay eggs on plant leaves.
• Eggs hatch to produce larva. It is also called caterpillar. It is very different from the adult butterfly.
• Larva/caterpillar moults to form pupa.
• Pupa changes to adult butterfly.
Useful insects :
Some insects are useful to us. They help us in many ways.
1. Honeybees collect nectar from flowers. They store it as honey. The beehive is made of wax, thus, we can say that wax is also produced by bees.
2. Some insects like butterflies, bees etc. help is pollination.
3. We get silk from the pupa of silk moth.
4. Many insects act as useful scavengers. They eat-up dead animals and plants.
Harmful insects :
1. Insects like grasshopper, beetle, locust etc. damage our crops, vegetables and fruits. They are called pests.
2. Mosquitoes spread diseases like malaria, filaria, yellow fever etc.
3. White ants, silver fish, cloth moths feed on the wood, paper and clothes in our homes. Thus, they cause damage to our household things.
Simple steps to get rid of unwanted insects :
1. Hair should be kept clean by washing and regular combing. This keeps hair healthy and free of head louse.
2. Moth balls or dried neem leaves should be kept with silk or woollen clothes. They keep insets away.
3. We should spray chemicals like D.D.T. and other insecticides in the places where insects live
PARTS OF AN INSECTS BODY
Most of the insects have six legs. The body of an adult insect is divided into three parts : head, thorax and abdomen. Insects have antennae on their head. This antennae is a thin whip like structure which helps the insect to smell and feel. Most of the insects have wings. These wings do not have strong flight muscles, hence they fly only for short intervals and short distance. Insects have a hard outer covering, called chitin on their body.
A cockroach has a set of antennae which helps it to locate its food, helps in movement.
Insects like butterfly have a long sucking tube in their mouth called proboscis. A butterfly uses this tube to suck nectar from a flower.
Most insects have two pairs of wings. In certain cases there is only one pair of wings as that of housefly.
Some insects don’t have wings. Ants and louse are wingless insects.
Insects breathe through tiny air holes called spiracles present on the body surface.
Small creatures that look like insects but are not insects.
There are many creatures which look like insects but they are not actually insects. Spider, scorpion, centipede, millipede, snail, earthworm etc. are such creatures commonly seen around us. But these are not put under the category of insects.
SOCIAL INSECTS
Some insects live together in colonies or communities. They live in societies like man. They are called social insects. Ants and bees are social insects.
The social life of such insects is very well-organised. Each member of the community has definite work to do. Like us, ants divide the work of the colony among them.
Queen ant : Queen ant spends all her life in laying eggs.
Male ants : A few winged male ants help the queen ants in laying eggs.
Female worker ants : Thousands of wingless female worker ants gather food, take care of eggs and maintain the colony.
Life cycle of a Butterfly
A butterfly completes its life cycle in four stages : egg, larva (caterpillar), pupa and adult.
• Butterflies lay eggs on plant leaves.
• Eggs hatch to produce larva. It is also called caterpillar. It is very different from the adult butterfly.
• Larva/caterpillar moults to form pupa.
• Pupa changes to adult butterfly.
Useful insects :
Some insects are useful to us. They help us in many ways.
1. Honeybees collect nectar from flowers. They store it as honey. The beehive is made of wax, thus, we can say that wax is also produced by bees.
2. Some insects like butterflies, bees etc. help is pollination.
3. We get silk from the pupa of silk moth.
4. Many insects act as useful scavengers. They eat-up dead animals and plants.
Harmful insects :
1. Insects like grasshopper, beetle, locust etc. damage our crops, vegetables and fruits. They are called pests.
2. Mosquitoes spread diseases like malaria, filaria, yellow fever etc.
3. White ants, silver fish, cloth moths feed on the wood, paper and clothes in our homes. Thus, they cause damage to our household things.
Simple steps to get rid of unwanted insects :
1. Hair should be kept clean by washing and regular combing. This keeps hair healthy and free of head louse.
2. Moth balls or dried neem leaves should be kept with silk or woollen clothes. They keep insets away.
3. We should spray chemicals like D.D.T. and other insecticides in the places where insects live
Assignment:- Read chapter-6 carefully and Do page No. 59 and 62 in the text book.
06/JULY/2021
CHAPTER 5: BIRDS AND THEIR CLAWS
Assignment:- Complete the following in your Science-OCB.
01/JULY/2021
CHAPTER 5: BIRDS AND THEIR CLAWS
Now watch this video for your better understanding:-
How do we walk? We have feet to stand and to walk. The birds normally fly but sometimes they stand on their claws to eat grains or the food stuff they like. They hold the branches with their claws and even protect themselves with their claws.
The claws of birds help them in number of ways :
• Help the birds to hold the branch.
• Help the birds to hold their prey.
• Help the birds to climb up the trees.
• Help the birds to walk and run on ground.
• Help the birds to scratch for seeds and worms.
Different birds have different types of claws. It actually depends on the functions which a bird has to perform. The functions can vary with food habits, type of nests it makes and the type of locomotion or movement. The main function of feet and claws is protecting themselves from their enemies and moving about. Depending upon the structure of claws, the birds can be classified as:
• Perching birds
• Scratching birds
• Climbing birds
• Wading birds
• Preying birds
• Swimming birds
1. Perching Birds
Birds like crow, sparrow etc. perch and hop on the branches. They have three toes in front and one at the back. Such toes help them to hold the branches firmly.
They hop on the ground and can even sleep while perching.
2. Climbing Birds
Birds like woodpecker and parrots have two toes pointing upwards and two downwards. Such toes help them to climb up the trees.
3. Preying Birds
Birds like eagles, hawks etc. have strong and sharp claws to catch and hold their prey. The claws of preying birds are called talons.
4. Scratching Birds
Birds like hens use their claws to scratch the earth for seeds and worms. Such birds are called scratching birds. They have sharp and hard claws with three toes in front and one at the back. These birds can both walk and run on the ground.
5. Wading Birds
Birds like cranes, herons walk in shallow water especially in search of food. Such birds are called wading birds. These birds have long legs and wide spreading toes. These toes keep the feet from sinking in the soft mud.
6. Swimming Birds or Aquatic Birds
Birds like ducks and swans swim in water. Such birds are called swimming or aquatic birds. These birds have webbed feet. These feet help them to paddle and push water while swimming.
NESTS OF BIRDS
As we all live in a house. Birds live in a nest. Nest is the dwelling place of a bird. They build their nest to lay eggs, keep their young ones safe and warm.
Different birds have different type of nests. The nests differ in the shape, size and nature of material used for building the nest.
• Bulbul’s Nest
Bulbuls build their nests in hedges and bushes with the help of grass. The nests look like a deep cup.
• Tailor Bird’s Nest
A weaver bird uses its beak to sew big leaves together with the help of thread, wool etc., to make a cosy nest.
• Woodpecker’s Nest
Woodpecker makes a hole into the trunk of a tree. This hole is used as a nest.
• Vulture’s Nest
Vultures use sticks to make big nests in tall trees.
• Owl’s Nest
Owls make their nest in the hollow of a tree. The nest is lined with feathers and grass.
The claws of birds help them in number of ways :
• Help the birds to hold the branch.
• Help the birds to hold their prey.
• Help the birds to climb up the trees.
• Help the birds to walk and run on ground.
• Help the birds to scratch for seeds and worms.
Different birds have different types of claws. It actually depends on the functions which a bird has to perform. The functions can vary with food habits, type of nests it makes and the type of locomotion or movement. The main function of feet and claws is protecting themselves from their enemies and moving about. Depending upon the structure of claws, the birds can be classified as:
• Perching birds
• Scratching birds
• Climbing birds
• Wading birds
• Preying birds
• Swimming birds
1. Perching Birds
Birds like crow, sparrow etc. perch and hop on the branches. They have three toes in front and one at the back. Such toes help them to hold the branches firmly.
They hop on the ground and can even sleep while perching.
2. Climbing Birds
Birds like woodpecker and parrots have two toes pointing upwards and two downwards. Such toes help them to climb up the trees.
3. Preying Birds
Birds like eagles, hawks etc. have strong and sharp claws to catch and hold their prey. The claws of preying birds are called talons.
4. Scratching Birds
Birds like hens use their claws to scratch the earth for seeds and worms. Such birds are called scratching birds. They have sharp and hard claws with three toes in front and one at the back. These birds can both walk and run on the ground.
5. Wading Birds
Birds like cranes, herons walk in shallow water especially in search of food. Such birds are called wading birds. These birds have long legs and wide spreading toes. These toes keep the feet from sinking in the soft mud.
6. Swimming Birds or Aquatic Birds
Birds like ducks and swans swim in water. Such birds are called swimming or aquatic birds. These birds have webbed feet. These feet help them to paddle and push water while swimming.
NESTS OF BIRDS
As we all live in a house. Birds live in a nest. Nest is the dwelling place of a bird. They build their nest to lay eggs, keep their young ones safe and warm.
Different birds have different type of nests. The nests differ in the shape, size and nature of material used for building the nest.
• Bulbul’s Nest
Bulbuls build their nests in hedges and bushes with the help of grass. The nests look like a deep cup.
• Tailor Bird’s Nest
A weaver bird uses its beak to sew big leaves together with the help of thread, wool etc., to make a cosy nest.
• Woodpecker’s Nest
Woodpecker makes a hole into the trunk of a tree. This hole is used as a nest.
• Vulture’s Nest
Vultures use sticks to make big nests in tall trees.
• Owl’s Nest
Owls make their nest in the hollow of a tree. The nest is lined with feathers and grass.
Assignment:- Read chapter -5 carefully and Do Page No. 49 and 52 in the text book.
17/JUNE/2021
CHAPTER 4: BIRDS AND THEIR BEAKS
Assignment:- Complete the following in your Science-OCB.
15/JUNE/2021
CHAPTER 4: BIRDS AND THEIR BEAKS
Now watch this video for your better understanding:-
Birds are beautiful creatures different from plants and animals. They are the animals with feathers. There are about 8600 species of birds.
Birds have light bodies. They have well formed wings attached to their body with the help of strong muscles. A bird flaps its wings in both directions i.e., upward and downward direction to fly.
The upward movement of wings is known as upstroke.
The downward movement of wings is known as downstroke.
FEATHERS
A bird’s body is covered with feathers. Each bird has different kinds of feathers.
1. Body feathers : Feathers which are small and of different colours and cover the body of birds are known as body feathers.
2. Down feathers : Down feathers are fluffy and soft. They keep the bird warm.
3. Flight feathers : Flight feathers are long and found mainly on the wings. They help the bird to fly.
All BIRDS CANNOT FLY
Some birds like ostrich and penguin cannot fly because they are too heavy to fly.
Aquatic Birds
Some birds can swim in water. Such birds are known as aquatic birds.
Features of Aquatic Birds
Aquatic birds have:
1. Oil-glands which keep their feathers water proof.
2. They have webbed feet which help them to swim in water.
Birds help in dispersal of seeds. They support out ecosystem and helps it to function smoothly.
BEAKS OF BIRDS
As we have mouth to eat, birds have beaks. The beak of bird is designed according to the food it eats. Thus, the shape of beak vary from bird to bird. Some birds use their beak to protect themselves from their enemies.
Types of Beaks
1. Small, hard and pointed beaks :
Birds like sparrow and pigeon which eat grains, seed and crack nuts have small, hard and pointed beaks.
2. Curved beaks :
Birds like parakeet have curved beak. This curved beak helps it to crack nuts and hard fruits. It also helps a parakeet to climb.
3. Strong, sharp and hooked beaks :
Birds like eagles, vultures, kites, owls and hawks have strong, sharp and hooked beaks for tearing the flesh of small birds.
4. Broad and flat beak :
Birds like ducks have broad and flat beaks. Such beaks help them to dig in soft mud and find worms for its food.
5. Strong and chisel-shaped beak :
Birds like woodpecker have strong and chisel shaped beak. It helps the woodpecker to make holes in tree trunk and catch insects for its food.
6. Broad and short beak :
Birds like swallow have broad and short beak. Its beak is sticky from inside. It has a very different way of feeding. It moves round and round in air with its beak open. Tiny flying insects get struck inside their beaks.
7. Broad, long and pointed beak :
Birds like kingfisher and storks have broad, long and pointed beaks to catch fish from rivers and ponds.
Birds have light bodies. They have well formed wings attached to their body with the help of strong muscles. A bird flaps its wings in both directions i.e., upward and downward direction to fly.
The upward movement of wings is known as upstroke.
The downward movement of wings is known as downstroke.
FEATHERS
A bird’s body is covered with feathers. Each bird has different kinds of feathers.
1. Body feathers : Feathers which are small and of different colours and cover the body of birds are known as body feathers.
2. Down feathers : Down feathers are fluffy and soft. They keep the bird warm.
3. Flight feathers : Flight feathers are long and found mainly on the wings. They help the bird to fly.
All BIRDS CANNOT FLY
Some birds like ostrich and penguin cannot fly because they are too heavy to fly.
Aquatic Birds
Some birds can swim in water. Such birds are known as aquatic birds.
Features of Aquatic Birds
Aquatic birds have:
1. Oil-glands which keep their feathers water proof.
2. They have webbed feet which help them to swim in water.
Birds help in dispersal of seeds. They support out ecosystem and helps it to function smoothly.
BEAKS OF BIRDS
As we have mouth to eat, birds have beaks. The beak of bird is designed according to the food it eats. Thus, the shape of beak vary from bird to bird. Some birds use their beak to protect themselves from their enemies.
Types of Beaks
1. Small, hard and pointed beaks :
Birds like sparrow and pigeon which eat grains, seed and crack nuts have small, hard and pointed beaks.
2. Curved beaks :
Birds like parakeet have curved beak. This curved beak helps it to crack nuts and hard fruits. It also helps a parakeet to climb.
3. Strong, sharp and hooked beaks :
Birds like eagles, vultures, kites, owls and hawks have strong, sharp and hooked beaks for tearing the flesh of small birds.
4. Broad and flat beak :
Birds like ducks have broad and flat beaks. Such beaks help them to dig in soft mud and find worms for its food.
5. Strong and chisel-shaped beak :
Birds like woodpecker have strong and chisel shaped beak. It helps the woodpecker to make holes in tree trunk and catch insects for its food.
6. Broad and short beak :
Birds like swallow have broad and short beak. Its beak is sticky from inside. It has a very different way of feeding. It moves round and round in air with its beak open. Tiny flying insects get struck inside their beaks.
7. Broad, long and pointed beak :
Birds like kingfisher and storks have broad, long and pointed beaks to catch fish from rivers and ponds.
Assignment:- Read chapter 4 and complete Pg. No. 38, 41 in the text book.
10/JUNE/2021
GENERAL SCIENCE CLASS TEST
TIME :- 09:20 AM
08/JUNE/2021
REVISION
CHAPTER 1: OUR BODY SYSTEMS
Just as a building is made-up of bricks, our body is made-up of cells.
Cells are building blocks of our body.
These cells join together to form complex organs and organ systems.
There are many organ systems in an organism. All these organ systems work efficiently in collaboration with each other.
ORGAN SYSTEMS
When few organs together carry out one major function for the body. They form an organ system. The different organ systems help a body to function properly. There are eight important systems in the body.
The Skeletal System
The skeletal system comprises of a bony framework. It gives shape and support to our body. There are 206 bones in our body. When joined together, they form the united framework called skeleton.
The Muscular System
Muscles are attached to the bones. Muscles help in body movement. There are more than 500 muscles in our body.
The Nervous System
Nervous system is made-up of the brain, the spinal cord and the nerves. This system helps us to think reason and act accordingly.
Sense Organs
Five sense organs i.e., eye, nose, tongue, ear and skhin receives information and conveys it to the brain. These senses organs are connected to the brain through network of nerves.
The Circulatory System
The circulatory system is composed of heart, blood and blood vessels. Blood flows in blood vessels. It carries oxygen and digested food to all parts of the body. An adult heart beats about 72 to 80 times in a minute.
The Respiratory System
When we breathe in, the air goes inside our body through our lungs. This air is used to oxidise the food and release energy. Energy released is used for doing various body activities.
The Digestive System
This system helps in the digestion of food. The food we eat passes through the food pipe and reach the stomach and then enter the intestines. Here, the complex food is broken down into simpler form and this is called digestion. The unwanted food is passed out of the body through the opening called anus.
The Reproductive System
This system helps to produce babies. It is this system which helps the life to go on.
The Excretory System
This system helps to remove the waste materials from the body. It is composed of kidney, ureter and urinary bladder.
Cells are building blocks of our body.
These cells join together to form complex organs and organ systems.
There are many organ systems in an organism. All these organ systems work efficiently in collaboration with each other.
ORGAN SYSTEMS
When few organs together carry out one major function for the body. They form an organ system. The different organ systems help a body to function properly. There are eight important systems in the body.
The Skeletal System
The skeletal system comprises of a bony framework. It gives shape and support to our body. There are 206 bones in our body. When joined together, they form the united framework called skeleton.
The Muscular System
Muscles are attached to the bones. Muscles help in body movement. There are more than 500 muscles in our body.
The Nervous System
Nervous system is made-up of the brain, the spinal cord and the nerves. This system helps us to think reason and act accordingly.
Sense Organs
Five sense organs i.e., eye, nose, tongue, ear and skhin receives information and conveys it to the brain. These senses organs are connected to the brain through network of nerves.
The Circulatory System
The circulatory system is composed of heart, blood and blood vessels. Blood flows in blood vessels. It carries oxygen and digested food to all parts of the body. An adult heart beats about 72 to 80 times in a minute.
The Respiratory System
When we breathe in, the air goes inside our body through our lungs. This air is used to oxidise the food and release energy. Energy released is used for doing various body activities.
The Digestive System
This system helps in the digestion of food. The food we eat passes through the food pipe and reach the stomach and then enter the intestines. Here, the complex food is broken down into simpler form and this is called digestion. The unwanted food is passed out of the body through the opening called anus.
The Reproductive System
This system helps to produce babies. It is this system which helps the life to go on.
The Excretory System
This system helps to remove the waste materials from the body. It is composed of kidney, ureter and urinary bladder.
Assignment:- Revise Chapter-1 for Class Test on 10/ June/ 2021.
03/JUNE/2021
CHAPTER 3: PLANTS
01/JUNE/2021
CHAPTER 3: PLANTS
Now watch this video for your better understanding:-
Plants are living organisms. They are fixed to the soil. Plants also have many body parts. There are different kinds of plants. These plants differ in height, structure and looks. Most of the plants grow in soil. Hence, we can divide the body of a plant into two main parts : root and shoot.
Similarly, the different parts of a plant perform different functions. Each plant part has an important task to do in the life of the plant.
Roots fix the plant to soil and shoot contain stem which bears fruits, flowers and buds.
ROOT
The part of the plant which remains under the ground is called the root.
Functions of Roots
• It holds the plant firmly to the soil.
• It helps to take up water and minerals from the soil.
• Some roots store the food and are used for eating.
Types of Roots
Roots are mainly of two types:
• Fibrous roots
• Tap roots
Fibrous Root System—When several tiny roots grow from the end of the stem, it is called fibrous root system.
Examples : Wheat and rice.
Tap Root System—When a single main root grows from the end of stem and many small roots grow from it, it is called a tap root system.
Examples : Cotton and mustard.
STEM
Stem is the main part of shoot. It bears leaves, buds and flowers. The main stem which is large and thick is called the trunk and the other thinner stems are called branches.
Functions of Stem
• The stem holds up leaves and flowers.
• It carries water to all parts of the plant.
• Hard stems support the plant.
• Weak and green stems prepare food for plant.
• Some stems store the food and are used for eating.
Types of Stem
Stem is broadly classified into three categories:
LEAF
Leaves are usually green coloured structures attached to the stem. The leaf absorbs maximum sunlight due to its flat surface.
Functions of Leaf
• Green leaves help the plant to prepare its food.
• Leaves contain stomata. It helps the leaves to breathe.
• Some leaves become thick and fleshy and store food. Such leaves can be used for eating.
FLOWERS
Flowers are the colourful structures attached to stem. They make the plant look attractive.
Functions of Flowers
• Flowers help in the reproduction of plant.
• Many flowers like rose and jasmine yield perfumes.
• Many flowers produce a sweet liquid called nectar.
• Some flowers change into fruit.
FRUITS
Fruits are the sweet edible part of a plant. Fruits also contain a sweet fragrance. Not only human beings but many birds and animals also eat fruits. Fruits are formed from flowers. They contain seeds.
The number of seeds are different in different fruits.
Functions of Fruits
• Fruits store the food material.
• Fruit contain the seeds which when sown give rise to a new plant.
Seeds
Seeds are the hard structures present in a fruit. Seed contain a tiny baby plant in it. This baby plant in the seed is protected by a seed coat.
Types of Seeds
Edible seeds: Seeds of some plants can be eaten. Such seeds are called edible seeds. e.g., Wheat and gram.
Non-edible seeds: Seeds of some plants cannot be eaten. Such seeds are called non-edible seeds. e.g., Orange and apple seeds. Seed is protected by a hard layer. When it is sown, the seed coat burst open and a baby plant emerge out. This baby plant grows into a healthy plant on receiving proper amount of sunlight, air, water and minerals from soil.
Similarly, the different parts of a plant perform different functions. Each plant part has an important task to do in the life of the plant.
Roots fix the plant to soil and shoot contain stem which bears fruits, flowers and buds.
ROOT
The part of the plant which remains under the ground is called the root.
Functions of Roots
• It holds the plant firmly to the soil.
• It helps to take up water and minerals from the soil.
• Some roots store the food and are used for eating.
Types of Roots
Roots are mainly of two types:
• Fibrous roots
• Tap roots
Fibrous Root System—When several tiny roots grow from the end of the stem, it is called fibrous root system.
Examples : Wheat and rice.
Tap Root System—When a single main root grows from the end of stem and many small roots grow from it, it is called a tap root system.
Examples : Cotton and mustard.
STEM
Stem is the main part of shoot. It bears leaves, buds and flowers. The main stem which is large and thick is called the trunk and the other thinner stems are called branches.
Functions of Stem
• The stem holds up leaves and flowers.
• It carries water to all parts of the plant.
• Hard stems support the plant.
• Weak and green stems prepare food for plant.
• Some stems store the food and are used for eating.
Types of Stem
Stem is broadly classified into three categories:
LEAF
Leaves are usually green coloured structures attached to the stem. The leaf absorbs maximum sunlight due to its flat surface.
Functions of Leaf
• Green leaves help the plant to prepare its food.
• Leaves contain stomata. It helps the leaves to breathe.
• Some leaves become thick and fleshy and store food. Such leaves can be used for eating.
FLOWERS
Flowers are the colourful structures attached to stem. They make the plant look attractive.
Functions of Flowers
• Flowers help in the reproduction of plant.
• Many flowers like rose and jasmine yield perfumes.
• Many flowers produce a sweet liquid called nectar.
• Some flowers change into fruit.
FRUITS
Fruits are the sweet edible part of a plant. Fruits also contain a sweet fragrance. Not only human beings but many birds and animals also eat fruits. Fruits are formed from flowers. They contain seeds.
The number of seeds are different in different fruits.
Functions of Fruits
• Fruits store the food material.
• Fruit contain the seeds which when sown give rise to a new plant.
Seeds
Seeds are the hard structures present in a fruit. Seed contain a tiny baby plant in it. This baby plant in the seed is protected by a seed coat.
Types of Seeds
Edible seeds: Seeds of some plants can be eaten. Such seeds are called edible seeds. e.g., Wheat and gram.
Non-edible seeds: Seeds of some plants cannot be eaten. Such seeds are called non-edible seeds. e.g., Orange and apple seeds. Seed is protected by a hard layer. When it is sown, the seed coat burst open and a baby plant emerge out. This baby plant grows into a healthy plant on receiving proper amount of sunlight, air, water and minerals from soil.
Assignment :- Read chapter -3 and Do page No. 29 and 32 in the text book.
27/MAY/2021
CHAPTER 2: THE RESPIRATORY SYSTEM
Assignment:- Complete the following in your Science OCB.
20/MAY/2021
CHAPTER 2: THE RESPIRATORY SYSTEM
Now watch this video for your better understanding:-
BREATHING
The process during which air rich in oxygen is taken in and air rich in water vapours and carbon dioxide is given out is known as breathing.
INHALATION
The process of taking in of air is known as inhalation.
EXHALATION
The process of giving out of air is known as exhalation. Breathing is a continuous process and occurs throughout the life of all organisms.
RESPIRATION
The process of breaking down the complex food substances with the help of oxygen and releasing energy is known as respiration.
Why do we respire ?
As all machines need energy to work. Similarly, our body also needs energy for its various activities. This energy is obtained by respiration of food we eat. Respiration takes place inside the body cells.
THE RESPIRATORY SYSTEM
The organs that help in respiration together form the respiratory system. Thus, the various parts of respiratory system includes nose, nasal passage, windpipe and lungs.
Nose and Nasal passage
We breathe through nose or nostrils. The nostrils contain hair. These hair trap dust particles and germs and send clean air for respiration. Thus, we should always
breathe through our nose.
Windpipe
The air from the nasal passage reaches the lungs through windpipe and then divides into two bronchi and then enter into the two lungs.
LUNGS
Lungs are the main respiratory organs in our body. They are a pair of spongy, elastic and bag like structures. When we breathe in, the lungs gets filled with fresh air. This air is taken by blood to all parts of the body and the used air is then given back to lungs.
The air we inhale contains lot of oxygen which is taken by lungs. In our body, the percentage of oxygen decrease because our body takes oxygen for respiration and gives out carbon dioxide. This gas is then given out of the body.
AIR POLLUTION
The mixing of harmful components in air is known as air pollution. Air pollution effects our respiratory system and cause number of diseases. The germs present in air enter into the respiratory tract and multiply causing various allergic diseases.
Sneezing : When we inhale, the germs are trapped by the hairs present inside the nose. Sometimes, these particles are not trapped and cause irritation. Thus, sneezing occurs to throw these particles out.
Coughing : If unwanted particles enter the respiratory tract, then coughing occurs to throw these particles out.
Asthma : The breathing difficulty that occurs due to an allergic disorder is known as asthma.
Other than these, polluted air cause common cold, headache, dizziness, inflammation of lungs and bronchitis. Common cold results from the germs that attack our body resulting in fever, nasal discharge, headache and reddening of eyes.
Precautions
1. Eating healthy food keeps our body healthy and prevents us from diseases.
2. Common cold is a communicable disease. Thus, keep a handkerchief infront of your nose while sneezing.
3. Take personal care of health and hygiene.
4. In case of severe cold, visit doctor.
How to ensure healthy breathing ?
1. Morning walk is very helpful because the air is clean and fresh.
2. Alpha breathing process increases the capacity of lungs.
3. People during yoga maintain good posture which helps to breathe properly.
4. Too much of fatty foods reduce the capacity of breathing and in turn leads to obesity.
Thus, healthy food and good posture helps in healthy breathing.
The process during which air rich in oxygen is taken in and air rich in water vapours and carbon dioxide is given out is known as breathing.
INHALATION
The process of taking in of air is known as inhalation.
EXHALATION
The process of giving out of air is known as exhalation. Breathing is a continuous process and occurs throughout the life of all organisms.
RESPIRATION
The process of breaking down the complex food substances with the help of oxygen and releasing energy is known as respiration.
Why do we respire ?
As all machines need energy to work. Similarly, our body also needs energy for its various activities. This energy is obtained by respiration of food we eat. Respiration takes place inside the body cells.
THE RESPIRATORY SYSTEM
The organs that help in respiration together form the respiratory system. Thus, the various parts of respiratory system includes nose, nasal passage, windpipe and lungs.
Nose and Nasal passage
We breathe through nose or nostrils. The nostrils contain hair. These hair trap dust particles and germs and send clean air for respiration. Thus, we should always
breathe through our nose.
Windpipe
The air from the nasal passage reaches the lungs through windpipe and then divides into two bronchi and then enter into the two lungs.
LUNGS
Lungs are the main respiratory organs in our body. They are a pair of spongy, elastic and bag like structures. When we breathe in, the lungs gets filled with fresh air. This air is taken by blood to all parts of the body and the used air is then given back to lungs.
The air we inhale contains lot of oxygen which is taken by lungs. In our body, the percentage of oxygen decrease because our body takes oxygen for respiration and gives out carbon dioxide. This gas is then given out of the body.
AIR POLLUTION
The mixing of harmful components in air is known as air pollution. Air pollution effects our respiratory system and cause number of diseases. The germs present in air enter into the respiratory tract and multiply causing various allergic diseases.
Sneezing : When we inhale, the germs are trapped by the hairs present inside the nose. Sometimes, these particles are not trapped and cause irritation. Thus, sneezing occurs to throw these particles out.
Coughing : If unwanted particles enter the respiratory tract, then coughing occurs to throw these particles out.
Asthma : The breathing difficulty that occurs due to an allergic disorder is known as asthma.
Other than these, polluted air cause common cold, headache, dizziness, inflammation of lungs and bronchitis. Common cold results from the germs that attack our body resulting in fever, nasal discharge, headache and reddening of eyes.
Precautions
1. Eating healthy food keeps our body healthy and prevents us from diseases.
2. Common cold is a communicable disease. Thus, keep a handkerchief infront of your nose while sneezing.
3. Take personal care of health and hygiene.
4. In case of severe cold, visit doctor.
How to ensure healthy breathing ?
1. Morning walk is very helpful because the air is clean and fresh.
2. Alpha breathing process increases the capacity of lungs.
3. People during yoga maintain good posture which helps to breathe properly.
4. Too much of fatty foods reduce the capacity of breathing and in turn leads to obesity.
Thus, healthy food and good posture helps in healthy breathing.
Assignment:- Do page No. 18 and 21 in the text book.
13/MAY/2021
CHAPTER 1: OUR BODY SYSTEMS
Now watch this video for your better understanding:-
Our Body
Our Body
The Nervous System
Nervous system is made-up of the brain, the spinal cord and the nerves. This system helps us to think reason and act accordingly.
Sense Organs
Five sense organs i.e., eye, nose, tongue, ear and skin receives information and conveys it to the brain. These senses organs are connected to the brain through network of nerves.
The Circulatory System
The circulatory system is composed of heart, blood and blood vessels. Blood flows in blood vessels. It carries oxygen and digested food to all parts of the body. An adult heart beats about 72 to 80 times in a minute.
The Respiratory System
When we breathe in, the air goes inside our body through our lungs. This air is used to oxidise the food and release energy. Energy released is used for doing various body activities.
The Digestive System
This system helps in the digestion of food. The food we eat passes through the food pipe and reach the stomach and then enter the intestines. Here, the complex food is broken down into simpler form and this is called digestion. The unwanted food is passed out of the body through the opening called anus.
The Reproductive System
This system helps to produce babies. It is this system which helps the life to go on.
The Excretory System
This system helps to remove the waste materials from the body. It is composed of kidney, ureter and urinary bladder.
Nervous system is made-up of the brain, the spinal cord and the nerves. This system helps us to think reason and act accordingly.
Sense Organs
Five sense organs i.e., eye, nose, tongue, ear and skin receives information and conveys it to the brain. These senses organs are connected to the brain through network of nerves.
The Circulatory System
The circulatory system is composed of heart, blood and blood vessels. Blood flows in blood vessels. It carries oxygen and digested food to all parts of the body. An adult heart beats about 72 to 80 times in a minute.
The Respiratory System
When we breathe in, the air goes inside our body through our lungs. This air is used to oxidise the food and release energy. Energy released is used for doing various body activities.
The Digestive System
This system helps in the digestion of food. The food we eat passes through the food pipe and reach the stomach and then enter the intestines. Here, the complex food is broken down into simpler form and this is called digestion. The unwanted food is passed out of the body through the opening called anus.
The Reproductive System
This system helps to produce babies. It is this system which helps the life to go on.
The Excretory System
This system helps to remove the waste materials from the body. It is composed of kidney, ureter and urinary bladder.
Assignment:- Do Ex- A to F from page No. 12 ,13 and learn Qs,ans of Chapter 1.
06/MAY/2021
CHAPTER 1: OUR BODY SYSTEMS
Now watch this video for your better understanding:-
Our Body
Our Body
Just as a building is made-up of bricks, our body is made-up of cells.
Cells are building blocks of our body.
These cells join together to form complex organs and organ systems.
There are many organ systems in an organism. All these organ systems work efficiently in collaboration with each other.
ORGAN SYSTEMS
When few organs together carry out one major function for the body. They form an organ system. The different organ systems help a body to function properly. There are eight important systems in the body.
The Skeletal System
The skeletal system comprises of a bony framework. It gives shape and support to our body. There are 206 bones in our body. When joined together, they form the united framework called skeleton.
The Muscular System
Muscles are attached to the bones. Muscles help in body movement. There are more than 500 muscles in our body.
Assignment :- Read page No. 6 ,7 and Do page No. 8 in the text book.
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