Cell Organelles	Main Functions
Cell wall	Surrounds and protects the cell. Make the cell stiff and strong.
Cell membrane	Holds and protects the cell. Controls the movement of materials in and out of the cell.
Cytoplasm	A watery gel - like material in which cell parts move.
Mitochondria	Produce and supply most of the energy for the cell.
Chloroplasts	Capture the energy from sunlight and use it to produce food for the cell by photosynthesis.

(i) Computers are used in various fields.
(ii) In textile shop it is used for billing.
(iii) Computers are used to control large and small machines.
(iv) Computers are most important educational tools for teachers and learners.
(v) In Railways it is useful to book tickets and for other purposes.
(vi) It is also used in banks, ATM's, Post offices and in many places.
(vii) We can save many data and convert it into information.

S.no	Property	deficiency disease
1	vitamin A	Night blindness
2	vitamin B	Beri beri
3	vitamin C	Scurvy
4	vitamin D	Rickets
5	vitamin E	Nervous weakness, dimming of eyesight
6	vitamin K	Weakness of the bones, teeth etc.

Linear motion - A coconut falling from a tree
Curvilinear motion - A car driving around a curve
Self rotatory motion - Motion of the wheel in a cart
Circular motion - Athlete running around a track
Oscillatory motion - Swinging of a pendulum
Irregular motion - Movement of people in a bazaar

When there is a change of position of an object with respect to time then it is called motion.
Types of motion:
a) Based on path:
i) Linear motion - a person walking on a straight path
ii) Curvilinear motion - throwing ball
iii) Circular motion - swirling stone tied to the rope
iv) Rotatory motion - a rotating top
v) Oscillatory motion - pendulum of clock
vi) Zig zag (or) Irregular motion - the motion of a bee
b) Based on duration:
i) period motion - movement of hour hand of a clock
ii) Non-periodic  - motion flapping of a flag in wind
c) Based on speed:
9) Uniform motion -  motion of a train at a constant speed
ii) Non-uniform motion - a vehicle moves in different speed

Measuring the volume of irregular solid by displacement method.

(i) Take a graduated measuring cylinder and a stone.
(ii) Fill with water to certain level and mark it.
(iii) Tie the stone with a piece of fine thread.
(iv) Immerse the stone completely in to the water.
(v) We can observe the water level and mark it.
(vi) The water level is increased.
(vii) Find the increased level of water.
(vii) It would be equal to the space taken by stone.
(viii) This will be the volume of irregular stone.

Distance travelled (d) = 400 km
Time taken (t) = 5 hour
Average Speed (s) = \(\frac{d}{t}=\frac{400}{5}=80\) 
Average Speed = 80 kmph (or) Km/hr.

To protect from the skin dry due to over heat.

Fire extinguishers throw a stream of carbon-, di-oxide while putting - off fire. Carbon-di-oxide covers the fire and cut-off the supply of fresh air to the burning things and stop burning.

a) melting of wax and
d) Solidification of the molten wax can be reversed.
Burning of candle is a physical / reversible change. That is,
\(\text { Solid wax } \underset{\text { Cooling }}{\stackrel{\text { Heating }}{\rightleftarrows}} \text { molten wax }\)

(i) Yes, the bulb will glow.
(ii)  A piece of zinc metal (such as a galvanized nail) and a piece of copper are inserted into a lemon and connected by LED bulb.
(iii) The zinc and copper are electrds and the juice (acetic acid) is a electrolyte.
(iv) Power generated by reaction of the metals in acetic acid.

We feel hot because the heat is transferred from atmosphere to your body. Heat energy flows from higher temperature to lower temperature.

(i) Using beakers, the mustard oil is separated by the process of decantation, because oil being lighter than water, floats on water.
(ii) Next filtration is using a funnel and filter paper and thus water gets separated from chalk powder and coins.
(iii) By hand-picking method, the coins are separated frorn chalk powder.

(i) Bone provide a frame work for the body.
(ii) Bones along with muscles help in movements such as walking, running chewing and dancing, etc., 

During monsoon, the biscuits placed in open lose its crispness. Sugar in biscuits takes up water from the atmosphere and become so soft.

No. Deforestation can be an undesirable change. That is, Deforestation is harmful to our environment and not desired by us.

No the cell used in the clock cannot give us an electric shock because the voltage is very low in the cell.

HEAT	TEMPERATURE
i) Heat is an energy	The measurement of warmness or coldness of a substance
ii) Heat not only depends on the temperature of the substance but also depends on how many molecules are there in the object	Temperature is related to how fast the atoms or molecules move or vibrate within the substance.
iii) Heat measures the total kinetic energy of molecules	Temperature measures the average kinetic energy of molecules
iv) SI unit of heat is Joule	SI unit of temperature is kelvin

Adaptive features of polar Bear : Thick skin for protection, White fur.
Adaptive features of Penguin : Paddle to swim, walk with two legs.

Pure substances are mixed with harmful and unwanted substances. This process is called adulteration.

Terrestrial plant	Aquatic plant
(i) Terrestrial habitats are the ones that are found on land like forest, grassland and desert.	(i) Aquatic habitat includes area that are permanently covered by water and surrounding areas that are occationally covered by water.
(ii) They are classified into three types.  1. Desert habitat 2. Grassland habitat 3. Forest habitat	(ii) They are two types 1. Fresh water habitat 2. Marine water habitat

Switch, Bulb and Battery are the parts of the electric circuit. Generator is the source of electricity.

Arteries, Veins and capillaries are the blood vessels.

The entry of food into the wind pipe is prevented by a flap like structure called epiglottis.

Cytoplasm is called as "Area of movement"

Cell wall and chloroplast found only in plant cell

Robert hook discovered the cell in 1665.

The roots of a plant take up air from the spaces between the soil particles.

If we remove plants from the aquarium
(i) All types of wastes created by aquatic animals, excess food and decaying materials level will increase in water.
(ii) The dissolved oxygen level in water will decrease.
(iii) Algae will grow due to excess nutrients and light in aquariums.
(iv) Some types of fish even breed and lay eggs on the leaves of ths plants. This will affect.

When solute is dissolved in a solvent it forms a solution.
Solute + Solvent ⟶ Solution

Changes which take place over a long period of time are known as Slow changes.

Plants decaying is a chemical change.

The Iron chain is the conductor from the above figures.

(i) The measurement of warmness or coldness of a substance is known as its Temperature.
(ii) SI unit of temperature is kelvin

The tail of the bird helps to change the direction of the movements.

The settling down of heavier component of a mixture when allowed to remain undisturbed for some time is called sedimentation.

We have to separate mixture,
(i) to remoe impurities
(ii) to separate useful components
(iii) to get a highty pure form substance

The green leaves prepare food by the.process of photosynthesis.

Based on habitat, plant are classified as
i) aquatic plants
ii) terrestrial plants.

(i) Data is the information that has to be processed.
(ii) They are in the form of numbers, alphabets and images.

A computer is an electronic device that process the data and information according to our needs.

i) Common cold
ii) Influenza

(a) Food items rich in fat - Ex: Butter, Ghee.
(b) vitamin deficiency diseases - Ex: Night blindness, Beri-beri

1 millimetre < 1 centimetre < 1 Metre < 1 kilometre.