Tuesday, 4 April 2023

6th Chp 8 Notes

         Class 6th Science Notes          

           Chapter 8 Body Movements        

What is Locomotion?

→ Locomotion is movement of the entire body from one place to another.

→ Locomotion forms a framework that gives shape and support to the body.

→ The human body consists of 206 bones.

→ Bones protect internal organs.

Parts of Human Skeleton

→ The bones present in our body form a framework this frame work is called Skeleton.

→ The human skeleton has two parts:

(i) The axial skeleton system: It includes the skull, vertebral column and the chest bones or the rib-cage.

(ii) Appendicular skeleton system: It includes hip girdles and shoulder and the limbs.

Types of joints in Human Body

Different types of Joints

(i) Ball and socket joints

(ii) Pivotal joints

(iii) Hinge joints

(iv) Fixed joints

(i) Ball and socket joints

→ It is a type of joint in which ball shape of one bone fitted into the hollow space of another bone known as socket.


(ii) Pivotal Joints

→ Pivotal joints allow for flexibility, extension, rotation and twisting.

(iii) Hinge Joint

→ It is found between two or more than two bones where we need back and forth movement.

(iv) Fixed Joint

→ It does not move in any direction.


Bones 

→ Skeletal structure is composed of hard material which is made up of calcium called bone.

Various shape and functions of bones

→ The number of small bones on the back side these small bones combine called as backbone, which is helpful in bending front and back.


→ Bones which joins the chest and the backbone is called ribs

→ If you will touch just below your stomach area you will find the presence of pelvic bone.

→ The skull is the most hard and tough bone of our body which protects our brain from any mechanical injuries.

Cartilage

→ It is softer and more flexible than bone. Cartilage is found between the joints of knee and hips.


Muscles

→ Muscles are attached to the bones and it is responsible for the movement of human body.

→ There is change in the length of muscle due to contraction and relaxation.


Gait(Locomotion) of Animals

Locomotion of Earthworm

→ Earth worms commonly found in soil, it do not have bones. Their body is segmented, forms rings all over.

Locomotion of Snail

→ Snails commonly found on land or in soil.

→ It possesses wavy movement with muscular contraction.

→ Snail has hard shell on its back but it is not made up of bone and not helpful in locomotion.

Locomotion of Cockroach:

→ Cockroach is an insect and is a terrestrial animal mostly a common household pet.

→ The body is divided into three parts—head, thorax, and abdomen.

→ 3 pair of legs is present in thoracic part which moves by the muscles present near its limbs (legs).

→ The body is covered with the outer hard exoskeleton.

→ It uses breast muscles for the movement of wings due to which they can fly.

Birds

→ Birds were egg laying animal with feathers, wings and beak.

→ Fore limbs of birds were modified into wings due to which these can fly.

→ Hind limbs are legs due to which they can jump, walk or swim as can be seen in ducks.

→ The skeleton of birds is hollow to reduce weight and the breastbone muscle use to move the wings up and down.

Fishes

→ Fishes found in oceans, rivers, lakes, aquarium etc.

→ Fishes has well-arranged skeleton covered with strong muscles.

→ This movement is helped by the fins present on tail and also the fins presents on body helps to balance the body while swimming.


Snakes

→ Snakes live on ground, water, on trees. These were legless reptile.

→ During its movement snakes creates curves in many loops which pushes them to the forward direction, they moves very fast but not in straight-line the motion created by snakes is called serpentine motion.
















6th chp 7 Notes

         Class 6th Science Notes       

      Chapter 7 Getting to know Plants      


From where does a plant come?

→ A plant comes from a seed.

→ This seed is covered with seed coats, which protect the seed.

→ This seed contain a baby plant inside, it has a tiny root towards the outer side.

→ The tiny root is termed as radicle.

→ It also has a tiny shoot towards the inner side.

→ The tiny shoot is termed as plumule.


Classification of plants on the growth habit

→ The plants are classified in five types based on growth habit:

(i) Herbs

(ii) Shrubs

(iii) Trees

(iv) Climbers

(v) Creepers

(i) Herbs

→ Have soft, green and weak stems. Usually its height is short and may not have many branches. It is used for food, flavouring, medicine or perfume.

→ Examples: rice, wheat, maize, sunflower, mint, etc.

(ii) Shrubs

→ They are bushy and have hard stems which do not bend easily. These plants have their stem branching out near the base.

→ Examples: lemon, China rose, jasmine, etc.

(iii) Trees

→ These are big plants which have strong and long stem. Live for many years.

Examples: mango, neem, banyan, coconut, etc.

(iv) Climbers

→ Plant that take support on neighbouring structures and climb up are called climbers. It has weak stems and cannot stand erect.

→ Examples: pea, grapes etc.

(v) Creepers

→ Plants which creep on the ground and spread out is called creepers. It has weak stems that cannot stand upright.

Example: pumpkin and watermelon.

Classification of Plants on the basis of life cycle

→ The Plants are classified in three types on the basis of life cycle:

(i) Annuals

(ii) Biennials

(iii) Perennials

(i) Annuals: Plants whose life cycle is completed in one season.

Examples: wheat and mustard.

(ii) Biennials: Plants whose life cycle requires two seasons for completion.

Example: carrot, radish and potato.


(iii) Perennials: Plants whose life cycle runs for more than two seasons.
Example: guava, babul and palm trees.

Parts of plants and their function

→ Plants are divided in 3 types based on their functions:
(i) Root System
(ii) Shoot System
(iii) Flowers

(i) Root system
→ The underground part of a plant is called root.

Types of root system:

(a) Tap root system
→ Primary root comes out from the seed after germination. It is also called true roots.

(b) Fibrous root system

→ These roots grow from the base of the stem have a bushy appearance. Fibrous roots are thin and almost equal in size.

Functions of roots

→ Help to anchor the plant firmly into the ground.

→ Root help plants to absorb water and nutrients from soil.

(ii) Shoot system

→ All parts of a plant that are above the ground form the shoot system.

Types of shoot system:

(a) Stem

→ It holds leaves in position and helps them to spread out as the stem and its branches grow.

→ It bears flowers, buds, leaves, and fruits.


(b) Leaf

→ A leaf is a flat and green structure on a plant, coming out from a node on the stem and always bearing a bud in its axil.

→ Parts of leaf are:

• Petiole

• Leaf lamina

• Veins

(iii) Flowers

→ A flower is the reproductive organ of a plant.

→ Flower gets developed into fruits and the fruits contain seeds with them for next generation.

Parts of flowers:

(i) Pedicle: Stalk of the flower through which the flower is joined to the branch.

(ii) Sepal: Small green leaf-like structure on the thalamus.

(iii) Petals: Petals attract the insects and help in the process of reproduction.

(iv) Stamens: These are male organs of the flower. It consists of two parts:

(a) Anther

(b) Filament

(v) Carpel: It is female organ of the flower. It consists of three parts:

(a) Style  (b) Stigma  (c) Ovary















Sunday, 19 March 2023

6th Chp 6 Notes


                          Class 6th Science Notes             

             Chapter 6 Changes Around Us            

Introduction

→ Changes can occur everywhere at any time.

→ Change is a continuous process.

→ Some changes are reversed and some cannot be reversed.

→ Change may occur by heating a substance or by mixing it with some other substance.

Common changes taking place in nature

→ Change in position, sun rise and set.

→ Change in colour, sky at day and at night time.

→ Change in shape, shape of moon.

→ Change in size, a germinate seed.

→ Change in temperature, hot summer and cold winter.

→ Change in state or form, water on cooling and heating.

→ Rusting of iron.

Types of changes

• Reversible changes

• Irreversible changes

• Chemical changes

• Physical changes

• Expansion And Contraction

Reversible changes

→ It is an effect on substance in which substance get returned to its original state.

→ The change only alters the physical state of the substance that means there is no new substance is formed.

→ Examples: melting of ice, water turning into vapour, inflation of balloon etc.

Irreversible change

→ In this process, the changes cannot be reversed are called irreversible changes.

→ In irreversible changes new material being produced, which may or may not be useful.

→ Examples: Ripening of fruits is an irreversible change because it is not possible to get back the raw fruits from ripened or mature ones.

→ Blooming of flowers is an irreversible change because flowers cannot change back into buds.

Physical changes

→ In this changes, there is no new substance is formed.

→ It is reversible

→ Examples: melting of wax, Melting of ice, crushing can etc.

Chemical 

→ In this change there is a new substance is formed after the change.

→ It cannot be reversed by simple physical means.

→ Examples: rusting of iron, burning of candle etc.

Expansion and Contraction

→ Some materials expand on heating and some material contract on cooling.

→ The amount of expansion differs in solids, liquids, Physical change and gases.

→ Gases material expands the most while solids material expands the least.

→ Solids material contract the least while gases material contract the most.

Causes of change

Force

→ It can bring changes in certain thing. It can change motion, shape and size of objects by push or pull.

→ Examples

(i) When a potter applies force on a lump of soil, it gives shape to the lump.

(ii) When a goldsmith hammers a piece of gold, he makes intricate designs on it.

Temperature

→ This brings changes by causing increase or decrease in temperature.

→ Examples

(i) When ice is kept on room temperature, it melts and turns into water.

(ii) When a candle begins burning, its wax start melts because of higher temperature. 






 

Saturday, 18 March 2023

6th Chp 5 Notes

             Class 6th Science Notes        

     Chapter 5 Separation of Substances    

What is Separation?

• The removal of substances from a mixture of two or more substances is known as separation.

• Some examples of separation are:

→ Separating stones from rice

→ Churning milk to obtained butter

Why do we need to separate substances?

→ To obtained two different components

→ To remove impurities or harmful components

→ To group substances of different sizes

Separation of substances

• Pure substance: The substance which contain only one type of particles.Examples: Water

• Impure substances: The substance which contain more than one kind of particle.

Examples: A plate of rice is mixed with some stones.

Separation of components of mixtures

• Mixture of solid with solid

(i) Hand picking

→ The component of a solid-solid mixture can be separated by hand picking.

→ It is used for separating large size impurities like stones and husk.

→ For example: separating grass from mint leaves, separating pebbles from dal.

(ii) Threshing

→ The process in which the stalks are beaten to free the grain seeds.

→ Threshing is done with the help of bullocks. For large quantity of grains machines are used for threshing.

→ This method is used by the farmers to separate the grains from the stalks after harvesting.


(iii) Winnowing

→ It is process which is used to separate heavier and lighter components of a mixture by wind or by blowing air.

→ This method is used by farmers to separate lighter husk particles from heavier seeds of grain.

(iv) Sieving

→ It is a process in which a components of a mixture with different size can be separated by sieve.

→ The smaller particles remove out through the pore of sieve and the larger particle is left behind it.

→ This method is used to separate wheat bran (the bigger particles) from flour.

(v) Sublimation

→ The process in which the solid changes directly into gaseous state on heating is called sublimation.


Mixtures of solids with liquids

(i) Evaporation

→ It is a process which is used when we want to get back a substance that has been dissolved. In this process liquid changes into gaseous form on heating.

→ Example: Getting salt out of salty water.


(ii) Crystallization

→ It is a process which separates a pure solid in the form of crystals from a saturated solution.

Separation of solids that do not dissolve in liquids

(i) Sedimentation: The process of separation of 2 components in such a way that the heavier substance settles down.

(ii) Decantation: separation of 2 components which do not mix together.

Example: Water and oil.

(iii) Filtration: The process in which separation of solid from liquid by the filter paper or strainer.Example: separating mud from water by using filter paper.

• Condensation: It is a process by which a substance changes from the gas phase to liquid phase.

Can water dissolve any amount of a substance?

→ Water dissolves different amounts of soluble substances in it.

→ A saturated solution is one which cannot dissolve more of that substance.

→ To dissolves more of a substance in a solution we have to heating it.