Category: Class 9th

Chapter 14: “Natural resources”

KEY CONCEPTS : [ *rating as per the significance of concept]

CONCEPTS	RATING
Breath of air	**
A wonder liquid	***
Biogeochemical cycles	*****

1. The” Biosphere” is the life supporting zone of the earthwith three sub-zones called as lithosphere (rock part), atmosphere (air part)and hydrosphere (water part).

Breath of air

1. Composition of Air

1. The interactions between different components of the Biosphere to maintain the balance between the biotic and a biotic component makes “Biogeochemical cycle”. Ex. Water Cycle, Nitrogen Cycle, Carbon cycle, Oxygen Cycle,
2. Role of atmosphere in climate control : atmosphere act as protective blanket for the earth. Since atmosphere is a bad conductor of heat, it keeps the average temperature of the earth constant. At night, it slows down the escape of heat into outer space.
3. The movement of air : the atmosphere gets heated from the radiation that is reflected back by the land or water bodies. As a result of heating, convection currents are set up in the air. Since land gets heated faster than water, the air over land gets heated faster than air above water bodies.
4. In coastal regions, during the day, the air above the land gets heated faster and starts rising. So a region of low pressure is created and air over sea moves into this area of low pressure. The movement of air from one region to the other region causes Wind.
5. During the day, the direction of wind would be from the sea to the land and at night, both land and sea starts to cool. Since water cools down slower than the land, the air above water would be warmer than air above land, thus the direction of wind would be from the land to the sea.
6. Air pollution : it is an undesirable change in the physical, chemical or biological characteristics. It is caused due to an increase in the content of harmful substances (pollutant) such as oxides of nitrogen and sulphur, etc.
7. 
   Harmful effect of air pollution :

• It affects the respiratory system causing breathing difficulties eg; bronchitis, asthma, lung cancer, tuberculosis, etc.
• Burning of fossil fuels like coal and petroleum releases oxides of nitrogen and sulphur. Inhalation of these gases is dangerous.
• Combustion of fossil fuel also increases the amount of suspended particles in air. The presence of high levels of all these pollutants, reduce visibility in cold weather where water also condenses out of air forming smog.
• Acid rain formed from the gases like sulphur dioxide and nitrogen oxides present in polluted air. It causes damage to living and non- living thing.

1. 
   The Water Cycle:
2. The process in which water evaporates and falls on the land as rain and later flows back into the sea via rivers is known as the “Water Cycle”. Water flows through rocks containing soluble minerals, some of them get dissolved in the water. Thus the rivers carry many nutrients from the land to sea and these are used by the marine organisms.
3. When the water vapors condense as water droplets and grow big and heavy, they fall down in the form of “rain”. It ranges from 5 cm to 200 cm of rain fall in a year in our country. In large parts of India, rains are mostly brought by the south-west or north-east monsoons. Depressions in the Bay of Bengal may also cause rains in some areas.
4. Water is a wonder liquid because all cellular processes take place in a water medium; substances are transported in a dissolved form; terrestrial forms require fresh water to maintain the equilibrium of salts; major resource to determine the life on the earth.
5. The dissolved fertilizers (NPK fertilizers), pesticides (DDT), sewage (Disease causing Organisms), waste from factories (Mercury) and water released from the dams can affect the life forms on the earth. The dissolved Oxygen is being used by the animals and plants that live in water, would adversely affect the aquatic organisms. The change in temperature would be dangerous for the eggs and larvae of the various animals particularly susceptible to temperature changes. It leads to “water pollution”.

(Please refer Fig. 14.5, NCERT Text Book Page-197).

1. Nitrogen Cycle:
2. The nitrogen gas makes up 78% of our atmosphere. It is essential for the synthesis of proteins, DNA, RNA, urea, alkaloids and Vitamins.
3. The simple molecular nitrogen from the atmosphere is converted into more complex molecules in the living beings and back again to atmosphere is called “Nitrogen Cycle”.
4. Nitrogen fixation by Lightening: During lightning, the molecular nitrogen is converted into oxides of nitrogen and dissolves in water to give nitric and nitrous acids and fall on lands along with rains. These are then utilized by various life forms.
5. Nitrogen fixation by Bacteria: The molecular nitrogen is converted into nitrates and nitrites, by free living bacteria or the bacteria present in the root nodules of legumes.
6. The conversion of molecular nitrogen into nitrates and nitrites is called as” Nitrification”. Plants generally covert them into amino acids. The conversion of nitrates and nitrates into Ammonia is called as” Ammonification”. The conversion of Ammonia into molecular Nitrogen is called as” Denitrification”. Thereby nitrates and nitrites are converted into molecular or elemental nitrogen in the nature. (Please refer Fig. 14.6, NCERT Text Book Page- 198).
7. The Carbon cycle:
8. The Carbon dioxide gas makes up 0.039 % of our atmosphere. Carbon occurs in the elemental form as diamonds and graphite in earth. Carbon is essential for the synthesis of proteins, carbohydrates, fats, nucleic acids and Vitamins in living organisms.
9. The Carbon dioxide Fixation: Green plants convert Carbon dioxide into glucose in the presence of sunlight through Photosynthesis. The glucose molecules are converted into other biologically important molecules. And many marine animals use carbonates dissolved in sea water to make shells, exoskeletons.
10. The combustion: The Carbon dioxide in the atmosphere is added by the process of combustion, where fuels are burnt to provide energy for various needs like heating, cooking, transportation, and industrial process.
11. The Greenhouse Effect: The percentage of Carbon dioxide in the atmosphere is said to have doubled since the industrial revolution when human beings stated burning fossil fuels on a very large scale. The Carbon dioxide is a greenhouse gas. The increase in the Carbon dioxide content would cause more heat to be retained by the atmosphere and lead to Global Warming. It is called” Greenhouse Effect”
12. The carbon cycle is repeated through different physical and biological activities. (Please refer Fig. 14.7, NCERT Text Book Page- 199).

6 .Oxygen Cycle:

1. The Oxygen gas makes up 21 % of our atmosphere. Oxygen is essential component of proteins, carbohydrates, fats, nucleic acids in living organisms.
2. Oxygen from our atmosphere is used up in three processes, namely combustion, respiration and in the formation of oxides of nitrogen. Oxygen is returned to the atmosphere in only one major process, that is, Photosynthesis, it is called as Oxygen Cycle.
3. The air is heated faster than water; the air over land would also be heated faster than the air over water bodies. The movement of air from one region to the other creates winds, during the day the direction of the wind would be from the sea to land. At night, both land and sea start to cool.
4. The oxides of nitrogen and sulphur gases dissolve in rain to gives rise to “Acid rains”. The smog is a visible indication of Air Pollution. The pollutants bring respiratory, cardiac problems and allergies. The organisms called Lichens are found on the bark of trees, they are indicators of pollution free environment. Three atoms of Oxygen ( O₃) is called as Ozone. The Ozone is poisonous but absorbs harmful radiations from the Sun. The Ozone layer around the earth, if, dwindles further may cause Health hazards including Cancers . Recently discovered the Ozone hole; in the region of Antarctica. (Please refer Fig. 14.8 & 14.9, NCERT Text Book Page- 200).

QUESTION BANK

1. What are the three sub-zones in the Biosphere? {Lithosphere (rock part), atmosphere (air part)and hydrosphere (water part)}.
2. The process in which water evaporates and falls on the land as rain and later flows

back into the sea via rivers is known (Water Cycle).

1. In large parts of India, rains are mostly brought by monsoons.( the south

west or north-east monsoons).

1. Why water is a wonder liquid? Justify ( A major resource to determine life on the earth)
2. What are the four major water Pollutants?{ (NPK fertilizers, pesticides (DDT), sewage (Disease causing Organisms), waste from factories (Mercury)}
3. Write a short notes on Nitrogen fixation by Bacteria.{The molecular nitrogen is converted into nitrates and nitrites, by free living bacteria or the bacteria present in the root nodules of legumes}.
4. What is Greenhouse Effect? {The Carbon dioxide is a greenhouse gas. The increase in the Carbon dioxide content would cause more heat to be retained by the atmosphere and lead to Global Warming. It is called” Greenhouse Effect”}
5. What is the percentage of Oxygen gas in our atmosphere? {21 %}
6. Which organisms are found on the bark of trees as indicators of pollution free environment? { Lichens}
7. Write about the Ozone hole in the Antarctica. {The Ozone layer around the earth is dwindling further to damage and cause Health hazards including Cancers. Recently discovered Ozone hole in the Antarctica.}

QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

Marks- 40 Time: 90 minutes

• General Instructions

1. Questions 1-5 (1 Mark each) 2. Questions 6-10 ( 2 Mark each)

1. Questions 11-15 (3Mark each) 4. . Questions 16-17 (5Mark each)

Q.1 What is called Lithosphere, define it.

Q.2 Water covers 75% of the Earth’s surface. Mention True/ false

Q.3 What is the percentage of Carbon dioxide on Venus

Q.4 What is the range of temperature on the Moon

Q.5 Define the term Pollutant

Q.6 What are the two ways to fix Carbon dioxide on earth.

Q.7 Mention any two important features of Water.

Q.8 How the Depressions effect our environment?

Q.9 Define the term Soil Pollution. Give one reason for it.

Q.10 How changes of temperature effect living organisms in water?

Q.11 What is Humus? Mention its importance in two points.

Q12 What is deforestation? Give two reasons for it.

Q.13. Define Global Warming, mention two causes for it.

Q.14 What is Ozone Depletion? Give two reasons for it.

Q.15 Draw the schematic diagram of Water Cycle in the nature.

Q.16. Write any five salient features of Nitrogen Cycle with a suitable diagram.

Q.17 Write about Industrial Pollution and mention five effects in the environment.

CHAPTER 12 – “Sound”

KEY CONCEPTS [ *rating as per the significance of concept]

1	Production of Sound	****
2	Propagation of Sound	*****
3	Reflection of Sound	*****
4	Echo	****
5	Uses Of Multiple Reflection Of Sound	***
6	Range of Hearing	***
7	Applications of Ultrasound	**
8	SONAR	**
9	Structure of Human Ear	****

1. 
   Production of Sound

Sound is produced due to the vibration of objects. Vibration is the rapid to and fro motion of an object.

Vibrating objects are the source of all sounds Irregular, chaotic vibrations produce noise Regular, controlled vibration can produce music All sound is a combination of pure frequencies A stretched rubber band when plucked vibrates and produces sound.

1. 
   Propagation of Sound

When an object vibrates, the particles around the medium vibrate. The particle in contact with the vibrating object is first displaced from its equilibrium position

The disturbance produced by the vibrating body travels through the medium but the particles do not move forward themselves.

A wave is a disturbance which moves through a medium by the vibration of the particles of the medium. So sound is considered as a wave.Sound waves Require medium for transmission.Sound waves are called mechanical waves. When a vibrating object moves forward, it pushes and compresses the air in front of it forming a region of high pressure called compression (C). When the vibrating object moves backward, it forms a region of low pressure called rarefaction (R).

Sound is longitudinal wave motion

A vibrating object producing a series of compressions (C) and rarefaction (R)

In these waves the particles move back and forth parallel to the direction of propagation of the disturbance. Such waves are called longitudinal waves.

There is another kind of waves called transverse waves. In these waves the particles oscillate up and down perpendicular to the propagation of the direction of disturbance.

Sound propagates in a medium as a series of compressions (C) and rarefactions (R).

Compressions are the regions of high pressure and density where the particles are crowded and are represented by the upper portion of the curve called crest.

Rarefactions are the regions of low pressure and density where the particles are spread out and are represented by the lower portion of the curve called trough Characteristics of a sound wave

Frequency of sound wave

The number of oscillations per unit time is called the frequency of the sound wave. It is represented by the symbol V (Greek letter nu). Its SI unit is hertz (Hz)

Time period of sound wave

Frequency and time are represented as follows:- V for one oscillation 1 1

T = — or V = —

V T

Amplitude of sound wave

The amplitude of sound wave is the height of the crest or tough. It is represented by the letter A.

The SI unit is the same as that of density or pressure.

Wavelength and Amplitude

The wavelength is the distance between the “crests” of two waves that are next to each other. The amplitude is how high the crests are.

Pitch and loudness of sound

The pitch of sound (shrillness or flatness) depends on the frequency of vibration.

If the frequency is high, the sound has high pitch and if the frequency is low, the sound has low pitch Speed of sound

The speed of sound is more in solids, less in liquids and least in gases.

The speed of sound also depends on the temperature of the medium. If the temperature of the medium is more, the speed of sound is more

1. 
   Reflection of Sound

Sound gets reflected at the surface of a solid or liquid and follows the laws of reflection.

1. The angle of incidence is equal to the angle of reflection.
2. The incident ray, the reflected ray and normal at the point of incidence all lie in the same plane.

Plate

o

► Screen

Renection of sound from a plane surface

4. Echo

If we shout or clap near a reflecting surface like tall building or a mountain, we hear the same sound again. This sound which we hear is called echo. It is caused due to the reflection of sound.

To hear an echo clearly, the time interval between the original sound and the echo must be at least 0.1 s.

Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344 m/s x 0.1 s = 34.4 m

So to hear an echo clearly, the minimum distance of the reflecting surface should be half this distance that is 17.2 m.

Reverberation

Echoes may be heard more than once due to repeated or multiple reflections of sound from several reflecting surfaces. This causes persistence of sound called reverberation.

In big halls or auditoriums to reduce reverberation, the roofs and walls are covered by sound absorbing materials like compressed fibre boards, rough plaster or draperies.

1. 
   Uses Of Multiple Reflection Of Sound

Megaphones, horns, musical instruments like trumpets, etc. are deigned to send sound by multiple reflection in a particular direction without spreading in all directions.

1. Doctors listen to sounds from the human body through a stethoscope. The sound of heartbeat reaches the doctor’s ears by multiple reflection.
2. Generally the ceilings of cinema halls and auditoriums are curved so that sound after multiple reflection reaches all parts of the hall.

Sometimes a curved sound board is placed behind the stage so that sound after multiple reflection spreads evenly across the hall.

1. 
   Range of Hearing

Human beings can hear sound frequencies between 20 Hz and 2000 Hz.

Sound whose frequency is less than 20 Hz is called infrasonic sound Sound whose frequency is more than 2000 Hz is called ultrasonic sound

1. _Uses of ultrasonic sound

Ultrasonic sound is used to clean objects like electronic Components, used to detect cracks in metal blocks, used in ultra sound scanners for getting images of internal organs of the human body used to break small stones formed in the kidneys into fine grains.

8 Sonar

It is a device which uses ultrasonic waves to measure distance, direction and speed of underwater objects. The distance of the object can be calculated by knowing the speed of sound in water and the time taken between the transmission and reception of ultrasound

The sound waves passes through the ear canal to a thin membrane called eardrum. The eardrum vibrates. The vibrations are amplified by the three bones of the middle ear called

hammer, anvil and stirrup. Middle ear then transmits the sound waves to the inner ear. The brain then interprets the signals as sound.

QUESTION BANK

One mark questions

1. What do you understand by sound waves?
2. Give an example to show that sound travels at a finite speed.
3. Is sound wave longitudinal or transfer.
4. Name two quantities that vary periodically at a place in air as a sound wave travels through it .
5. An airplane produces a sound wave with frequency of 5 KHz and wavelength 30 m. In how much time would the sound wave cover the distance of 4 Km?
6. With the help of a diagram show how longitudinal waves like sound waves travel in air.
7. With the help of a diagram show how longitudinal waves like sound waves travel in air.
8. Can we hear the ringing of a mobile phone placed in a vacuum chamber?
9. Can two astronauts talk on moon a they does on the surface of the earth?

Two marks questions

1. Explain how echoes are used by bats to judge the distance of an obstacle?
2. State the special properties of ultrasound that make it useful to us .In general, how these properties are utilized.
3. Why is soft furnishing avoided in concert halls?
4. Draw a diagram depicting low pitched sound and high pitched sound and write main difference between the two?
5. Distinguish between longitudinal and transverse waves. Give one example each.
6. An explosion takes place at the moon. After what time would it be heard at the earth?

Three marks questions

1. Two sources A and B vibrate with the same amplitude. They produce sounds of frequencies 1 kHz and 30 kHz respectively. Which of the two waves will have greater power?
2. Find the time period of the source of a sound wave whose frequency is 400Hz.
3. A sound wave travels at a speed of 340m/s. If its wavelength is 2 cm, what is the frequency of the wave? Will it be in the audible range?
4. The grandparents and parents of a two year girl are playing with her in a room. A sound source produces a 28—kHzsound.who in the room is most likely to hear the sound?

Five marks questions

1. Sound cannot travel in vacuum. Describe an experiment to demonstrate this.
2. With the help of a diagram describe how compression and rarefaction pulses are produced in air near a source of sound.
3. Explain briefly how a flaw in a mental component can be detected using ultrasound?
4. Explain the working and application of SONAR.
5. A monkey drops a coconut from the top of a tree. He hears the sound of the coconut hitting the ground 2.057 seconds after dropping it .If the monkey was 19.6 metres above the ground, what is the speed of sound in air?(take g = 9.8m/s²).
6. Draw a neat diagram of human ear. Explain the function of various parts. What have you learnt

Longitudinal waves: Those in which the direction of vibration is the same as their direction of propagation. So the movement of the particles of the medium is either in the same or in the opposite direction to the motion of the wave. Exemple: sound waves, what changes in this case is the pressure of the medium (air, water or whatever it be).

Transverse waves: The oscillations occur perpendicularly to the direction of energy transfer. Exemple: a wave in a tense string. Here the varying magnitude is the distance from the equilibrium horizontal position

A general property of waves is that their speed relative to medium depends on the properties of medium but is independent of the motion of the source of waves. If the observer is in motion with respect to the medium, the velocity of wave propagation relative to the observer wil be different. A remarkable exception is encountered in the case of light PROPERTIES Frequency

• Wavelength
• Period
• Amplitude
• Intensity
• Speed
• Direction Perception of Sound

For humans, hearing is limited to frequencies between about 20 Hz and 20000 Hz, with the upper limit generally decreasing with age.

KEY LEARNING:

Vibration – repetitive back and forth motion Periodic motion – a motion that repeats itself Mechanical waves require medium for propagation Waves move through medium but medium remains in place

Longitudinal waves-Vibration direction parallel to wave propagation direction Particles in medium move closer together/farther apart .Example: sound waves Gases and liquids – support only longitudinal waves Transverse waves-

Vibration direction perpendicular to wave propagation direction .Example: plucked string Solids – support both longitudinal and transverse waves Sound waves Require medium for transmission

1. Sound is a wave motion, produced by a vibrating source.
2. A medium is necessary for the propagation of sound waves.
3. Sound is a longitudinal wave in which the particles of medium move along the direction of motion of wave.
4. The part or region of a longitudinal wave in which the density of the particles of the medium is higher than the normal density is known as compression.
5. The part or region of a longitudinal wave in which the density of the particles of the medium is lesser than the normal density is called a rarefaction.
6. The point of maximum positive displacement on a transverse wave is known as crest.
7. The point of maximum negative displacement on a transverse wave is known as through.
8. A wave or short duration which is confined to a small portion of a medium at any given time is known as a pulse.
9. The maximum displacement of particles of the medium from their mean positions during the propagation of a wave is known as amplitude of the wave.
10. The distance traveled by a wave in one second is called wave velocity. It depends upon the nature of the medium through which it passes.
11. The speed of sound depends primarily on the nature and the temperature of the transmitting medium.
12. Sound travels faster in solids than in air. The speed of sound in solids is much more than the speed of sound in liquids or gases.
13. The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength.
14. Frequency is defined as the number of oscillations per second.
15. The time taken by the wave for one complete oscillation of the density or pressure of the medium is called the time period, T.
16. How the brain interprets the frequency of an emitted sound is called the pitch of sound.
17. Loudness is the degree of sensation of sound produced.
18. Sound properties such as pitch, loudness and quality are determined by the corresponding wave properties.
19. Sound gets reflected and follows the same law as the reflection of light.
20. The persistence of sound due to repeated reflection and its gradual fading away is called reverberation of sound.
21. Echo is a repetition of sound due to the reflection of original sound by a large and hard obstacle.
22. The audible range of hearing for average human beings is in the frequency range of 20 Hz – 20 kHz.
23. The amount of sound energy passing each second through unit area is called the intensity of sound.
24. Sound of frequency less than 20 Hz is known as infrasound and greater than 20 kHz is known as ultrasound.
25. Ultrasound has many medical and industrial applications.
26. SONAR stands for Sound Navigation and Ranging and it works on the principle of reflection of sound waves.
27. The SONAR technique is used to determine the depth of the sea and to locate under water hills, valleys, submarines, icebergs sunken ships etc.

CHAPTER 11 “Work & Energy”

KEY CONCEPTS [ *rating as per the significance of concept]

1	Work Done By A Constant Force	***
2	Energy And Its Forms(Kinetic Energy & Potential Energy) Are Various Energy Forms Inter convertible?
3	Potential Energy Of An Object At A Height	*****
4	Law Of Conservation Of Energy	****
5	Rate Of Doing Work & Commercial Unit Of Energy	****

1. Work Done By A Constant Force

• Work is a scalar quantity equal to the product of the displacement x and the

component of the force F_x in the direction of the displacement..

• Work is defined as a force acting upon an object to cause a displacement
• Mathematically, work can be expressed by the following equation.
• W= F x d cos q ( cos 0⁰ = 1)
• where F = force, d = displacement, and the angle (theta) is defined as the angle between the force and the displacement vector
• Three things are necessary for the performance of work:
• There must be an applied force F.
• There must be a displacement x.
• The force must have a component along the displacement

Negative Work

Force F contributes to displacement x.

Test Yourself:

1. Calculate Work when F= 40 N and x = 4 m.
2. Calculate Work when F = -10 N and x = 4 m.
3. A lawn mower is pushed a horizontal distance of 20 m by a force of 200 N directed at an angle of 30⁰ with the ground. What is the work of this force?
4. A student lifts a 50 pound (lb) ball 4 feet (ft) in 5 seconds (s). How many joules of work has the student completed?

2.Energy And Its Forms

James Joule

The metric system unit of energy is the joule (J), after James Joule.

• Mechanical energy is the energy which is possessed by an object due to its motion or its stored energy of position

Forms of Energy

• Kinetic energy : is the energy of motion

Energy which a body possesses because of its motion, which occurs anywhere from an atomic level to that of a whole organism

Examples of Kinetic Energy: This is not an all-inclusive list.

• Electrical – The movement of atoms
• Electromagnetic or Radiant – The movement of waves
• Thermal or Heat – The movement of molecules
• Motion – The movement of objects
• Sound – The movement through waves

Engineers generally refer to thermal/heat energy as “internal energy” and use “kinetic energy” strictly in reference to motion.

Potential Energy (Stored energy or gravitational energy)

• The capacity to do work by virtue of position or configuration
• an object can store energy as the result of its position or elastic source
• Potential Energy is maximum at the maximum HEIGHT

Energy transformation involves the conversion of one form of energy into another form. Examples of energy transformation include:

• Chemical – Food is consumed and converted into motion for playing sports or taking a test.
• Radiant – Sunlight is consumed by plants and converted into energy for growth.
• Electrical – Energy transferred to an oven is converted to thermal energy for heating our food.

Now you know the basic forms of energy. The next question is “What are the energy sources?”

There are renewable and nonrenewable sources of energy. A renewable energy source is a form of energy that is constantly and rapidly replenished by natural processes. Examples of renewable energy sources include:

• Biomass – The use of a living or once living organism as fuel
• Hydropower – The energy produced from the movement of water
• Geothermal – The use of heat from within the Earth or from the atmosphere

near oceans to warm houses or other buildings

• Wind – The use of wind to generate electricity

Solar – The use of the sun as a source of heat; for instance, to heat a room within a house, etc.

Energy Conversion Examples

Fossil fuels Chemical -> Heat -> Mechanical -> Electrical Solar cells Sunlight -> Electrical Wind turbines Kinetic ^ Mechanical -> Electrical Hydroelectric Gravitational potential -> Mechanical -> Electrical Nuclear Nuclear -> Heat -> Mechanical -> Electrical Vehicle System Conversion

Test Yourself

1. How much potential energy is lost by a 5Kg object to kinetic energy due a decrease in height of 4.5 m.
2. Potential energy of an object at a height

An object increases its energy when raised through a height.

The potential energy of an object at a height depends on the ground level or the zero level

1. Law Of Conservation Of Energy

The principle of Conservation of Mechanical Energy

The total mechanical energy (E=KE+PE) of an object remains constant as the object moves, provided that the net work done by external non-conservative forces is zero, W_nc=0J Total mechanical energy: the sum of kinetic energy and gravitational potential energy E = KE + PE

Wnc = (KEf – KE0) + (PEf – PE0)

Wnc = (KEf + PEf) – (KE0 + PE0)

Wnc = Ef – E0

Ef = KEf + PEf) E0 = KE0 + PE0

1. Rate of Doing Work & Commercial Unit Of Energy POWER

Rate at which work is performed or energy is expended

t

Watt is the base unit of Power

One watt is equal to 1 joule of work per second

Types of Power

• Electrical Power

Uses electrical energy to do work

• Mechanical Power

Uses mechanical energy to do work (linear, rotary)

• Fluid Power

Uses energy transferred by liquids (hydraulic) and gases (pneumatic)

• Power is the rate that we use energy.
• Power = Work or Energy / Time
• P = W/t = F x d/t = F v
• The unit joule is too small .The bigger unit of energy called kilowatt hour (kW h) 1 kW h is the energy used in one hour

at the rate of 1000 J s-1 (or 1 kW).

1 kW h = 1 kW *1 h = 1000 W*3600 s = 3600000 J 1 kW h = 3.6 x 10⁶ J.

Test Yourself

1. A 5 Kg Cart is pushed by a 30 N force against friction for a distance of 10m in 5 seconds. Determine the Power needed to move the cart.
2. A student lifts a 50.0 pound (lb) ball 4.00 feet (ft) in 5 .00seconds (s). How many watts of power are used to lift the ball?

Important Points for Work Problems:

• Always draw a free-body diagram, choosing the positive x-axis in the same direction as the displacement.
• Work is negative if a component of the force is opposite displacement direction
• Work done by any force that is at right angles with displacement will be zero (0).
• For resultant work, you can add the works of each force, or multiply the resultant force times the net displacement.
• Energy is the ability to move
• Potential is stored energy (Statics)
• Dependant on height
• Kinetic is moving energy (Dynamics)
• Dependant on velocity
• Springs store energy dependant on distance and constant

QUESTION BANK

One mark questions

1. Does work have a direction?
2. Does the kinetic energy of an object depend on its direction of motion?
3. Cam matter be converted into energy?
4. Give an example of conversion of chemical energy into heat energy.

Two marks questions

1. Two persons do the same amount of work. The first person does it in 10 s and the second, in 20 s.Find the ratio of the power used by the person to that by the second person.
2. A body of mass 25 g has a momentum of 0.40 kgm/s.Find its kinetic energy.
3. Define work and write its units.
4. By what factor does the kinetic energy of an object depend on its direction of motion?

Three marks questions

1. How much time will it take to perform 440 j of work at a rate of 11 W.
2. A body of mass 3.0kg and a body B of mass 10 kg are dropped simultaneously from a height of 14.9m.Calculate their Momenta, their Potential energies and kinetic energies when they are 10m above the ground.
3. lA man does 200j ofl work in 10 seconds and a boy does 100j of work in 4 seconds. Who is delivering more power? Find the Ratio of power delivered by the man to that by the boy.

Five marks questions

1. Show that the work done by a force is given by the product of the force and the projection of the displacement along the force.
2. Find the expression for gravitational potential energy of a body of mass m at height h.
3. Why does a person standing for a long time get tired when he does not appear to do any work?
4. How can you justify that a body kept at a greater height has larger energy?

CHAPTER 10- “GRAVITATION”

KEY CONCEPTS [ *rating as per the significance of concept]

1	Gravitation	***
2	Universal Law Of Gravitation	****
3	Free Fall	**
4	To Calculate The Value Of G	****
5	Mass & Weight	***
6	Weight Of The Object On Moon	***
7	Thrust & Pressure	***
8	Pressure In Fluids	***
9	Buoyancy	****
10	Why Objects Float Or Sink When Placed On The Surface Of Water?	***
11	Archimedes’s Principle	*****
12	Relative Density	***

Gravity is one of the most basic forces in the universe. It plays a fundamental role not only in the structure of our solar system but also in the way objects behave on Earth. In this section, we will talk about gravity on a small scale. We will discuss topics such as weight, free fall, and ballistics. We will learn the physics of phenomena we experience daily and take for granted

1.Gravitation

Gravitation is the force of attraction between two objects in the universe.

Gravitation may be the attraction of objects by the earth.

This force is proportional to the product of masses of the objects and inversely proportional to the square of the distance between them. It is independent of medium.

_ , , GMm

Gravitational force = ——

r^z

Eg If a body is dropped from a certain height, it falls downwards due to earth’s gravity.

If a body is thrown upwards, it reaches a certain height and then falls downwards due to the earth’s gravity.

• Gravitation may be the attraction between objects in outer space.

Eg :- Attraction between the earth and moon.

Attraction between the sun and planets.

GRAVITY

• A natural force that pulls all objects toward the center of the earth
• keeps the moon orbiting
• It holds stars together . . .
• And binds galaxies together for billions of years ….Prevents Planets from losing their atmospheres.

Test yourself:

1. When we move from the poles to the equator. Hence, the value of g decreases. Why?
2. What is the difference between gravity and gravitation?

2.Universal law of gravitation: – “Inverse square law”- All bits of matter attract all other bits of matter

• The universal law of gravitation states that, ‘Every object in the universe attracts every other object with a force which is directly proportional to product of the masses and inversely proportional to the square of the distance between them.’
• The strength of the gravitational attraction between two objects depends on two factors:

• The SI unit of G is N m² kg ^-2 and its value is 6.673 x 10^-11 N m² kg ^-2
• How big the objects are (how much mass they have) and
• How far apart they are.

Test Yourself

1. What is the difference between gravity and gravitation?
2. What does it mean to say that the Force of gravity is proportional to the masses

of the bodies, and inversely proportional to the distance between them?

3. Free Fall

• With negligible air resistance, falling objects can be considered freely falling. objects of different shapes accelerate differently (stone vs feather)

Test Yourself

1. A coin and a feather are dropped from the roof of a building. Which one will fall to the ground first

4 .To calculate the value of” g “(acceleration due to gravity)

• The acceleration due to gravity is denoted by g.
• The unit of g is same as the unit of acceleration ms ^-2
• From the second law of motion, force is the product of mass and acceleration.

F = ma

• For free fall, force is the product of mass and acceleration due to gravity.

GMm

F = mg or mg = =

GM

or g = — where M is the mass of the

Earth and d is the distance between the object and the earth.

• For objects near or on the surface of the earth d is equal to the radius of the earth R

GMm

• F = mg or mg = =

GM

• or g = —

Test Yourself

1. Calculate the value of g on the surface of earth.
2. What is the difference between “weight” and “mass”?
3. Mass and Weight:

• Mass is a fundamental, universal property. You have the same amount of mass no matter where you are in the Universe.
• Weight is not fundamental its value depends on circumstances in the Universe. Weight is a force. It is the resultant gravitational force exerted on a body with mass m by all the other bodies on the Universe.

Weight = F_g = G m M_e / R² = mg where M_e is the mass of the Earth and R is the radius of the Earth.

Test Yourself

1. An astronaut has 80 kg mass on earth (a)what is his weight on earth? (b) What

will be his mass and weight on mars where g=3.7 m/s² ‘

1. When you put an object on a spring balance, do you get the mass of an object or its weight?
2. 
   Weight Of The Object On Moon

• The mass of the moon is less than the mass of the earth. So the moon exerts lesser force on the objects than the earth.
• The weight of an object on the moon is one sixth (1/6^th) of its weight on the earth.
• The weight of an object on the earth is the force with which the earth attracts the

object and the weight of an object on the moon is the force with which the moon attracts the object.

Celestial body	Mass (kg)	Radius (m)
Earth	5.98 x 1024	6.37 x 106
Moon	7.36 x 1022	1.74 x 106

Test Yourself

1. What will be the weight of the body on the moon whose mass is12 kg?
2. 
   Thrust & Pressure

• Thrust is the force acting on an object perpendicular to the surface.
• Pressure is the force acting on unit area of a surface

Thrust

Pressure =

Area

• The SI unit of thrust is N/m² or N m^-2 . It is called Pascal (Pa).

1. Pressure In Fluids

• . Fluids exert pressure in all directions
• Pressure exerted on fluids is transmitted equally in all directions.

1. Buoyancy

When an object is immersed in a fluid it experiences an upward force called buoyant force. This property is called buoyancy or upthrust.

1. Why objects float or sink when placed on the surface of water?

• Take some water in a beaker. Take a piece of cork and an iron nail of the same mass. Place them on the water. The cork floats and the nail sinks.
• If the density of an object is less than the density of a liquid, it will float on the liquid and if the density of an object is more than the density of a liquid, it will sink in the liquid.

1. Archeimedes Principle

• Archimedes’ principle states that, When a body is partially or fully immersed in a fluid it experiences an upward force that is equal to the weight of the fluid displaced by it.’

12 .Relative density

• The relative density of a substance is the ratio of the density of a substance to the density of water. It is a ratio of similar quantities and has no unit.

QUESTION BANK

One Mark questions

1. Explain what Centrifugal force is.
2. What do you mean by the weight of the body on moon.
3. Give the value of G with proper units.
4. Give the value of g with proper units.
5. What is measured by physical balance?

Two Marks questions

1. At what height above the earth’s surface would the value of acceleration due to gravity be half of what it is on the surface? Take radius of earth to be R.

2 . A body of 90 kg f on the surface of earth. How much will it weigh on the surface of moon whose mass is 1/9 and radius is V of that of earth?

1. A piece of paper takes much longer to fall than a stone through the same distance. Explain the reason.
2. Consider a heavenly body which has a mass twice that of the earth and radius thrice that of the earth .What will be the weight of the book on this heavenly body, if its

weight on earth is 900 N?

Three Marks questions

1. Why gravitational force is usually unnoticeable?
2. Prove that acceleration due to gravity is independent of mass of the body.
3. How can the average density of the earth can be determined?
4. What is buoyancy and buoyant force? Upon what factors do they depend Five Marks questions
5. Find the percentage change in the weight of a body when it is taken from equator to poles. The polar radius is 6,357 Km and equatorial radius is 6,378 Km.
6. The density of ice is 918kgm-3 and that of sea water is 1,030kgm-3.An iceberg floats with a portion 224 liters outside water. Find the volume of iceberg.
7. What are the laws of flotation? Give some illustrations.

CHAPTER -9 “Force & Laws Of Motion”

KEY CONCEPTS [ *rating as per the significance of concept]

1	Balanced and Unbalanced Forces	***
2	Laws of Motion	*****
3	Inertia and Mass	*****
4	Conservation of Momentum	****

The Effect of Mass

A force applied to an automobile will not have the same effect as the same force applied to a pencil. An automobile resists accelerating much more than a pencil does, because it has more inertia, or mass.

The acceleration of an object depends not only on how hard you push on it, but also on how much the object resists being pushed.

What is the effect of mass on acceleration? This, too, turns out to be quite simple (I wonder why…). For the same force, an object with twice the mass will have half the acceleration. If it had three times the mass, the same force will produce one-third the acceleration. Four times the mass gives one-fourth of the acceleration, and so on.

This type of relationship between quantities (double one, get half the other) is called an inverse proportion or inverse variation. In other words, then:

Newton’s Second Law of Motion The acceleration of an object is dependent upon both force and mass. Thus, if the colliding objects have unequal mass, they will have unequal accelerations as a result of the contact force which results during the collision.

Newton’s Third Law Newton’s Third Law is stated as:

For every action there is an equal and opposite reaction.

“action…reaction” means that forces always occur in pairs. (Forces are interactions between objects, like conversations are interactions between people.)

Single, isolated forces never happen. The two forces involved are called the “action force” and the “reaction force.”

These names are unfortunate for a couple of reasons :

Either force in an interaction can be the “action” force or the “reaction” force

The action and reaction forces exist at the same time.

“equal” means

Both forces are exactly the same size. They are equal in magnitude.

Both forces exist at exactly the same time. They both start at exactly the same instant, and they both stop at exactly the same instant. They are equal in time.

“opposite” means that the two forces always act in opposite directions – exactly 180^o apart.

Newton’s third law of motion In every interaction, there is a pair of forces acting on the two interacting objects. The size of the force on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs – equal and opposite action- reaction force pairs.

Newton’s third law of motion applied to collisions between two objects. In a collision between two objects, both objects experience forces which are equal in magnitude and opposite in direction. Such forces cause one object to speed up (gain momentum) and the other object to slow down (lose momentum). According to Newton’s third law, the forces on the two objects are equal in magnitude.

Test Yourself

1. Can action reaction balance each other?
2. What does a force do?
3. 
   Inertia and Mass

Inertia is the tendency of an object to resist any change in its motion. An object will continue to move at the same speed in the same direction

unless acted upon by an unbalanced force. Inertia & Mass Inertia & Mass of a bowling ball rolled down the road would eventually come to a stop. Friction is an unbalanced force that causes the ball to stop or slow down. Without friction, the ball would keep going.

Inertia & Mass of a bowling ball and a tennis ball have the same inertia. Inertia & Mass If you had a tennis racket and I threw tennis ball at you, what would happen? If you had a tennis racket and I threw a bowling ball at you, what would happen? Why could you change the motion of the tennis ball but not the motion of the bowling ball?

Mass is the amount of matter in an object. A bowling ball has more mass than a tennis ball. The greater the mass of an object the greater its inertia. Mass is the measurement of inertia.

Test Yourself

1. Why do we fall forward if we alight from a moving bus?
2. Why does an athlete run for some distance before long jump?
3. Conservation of Momentum

Law of Conservation of Momentum

In a closed system, the vector sum of the momenta before and after an impact must be equal.

Before After

m₁v₁ +m₂v₂ = m₁v₁‘ + m₂v₂‘

Internal and External Forces

QUESTION BANK

One Mark questions

1. Define momentum.
2. State first law of motion.
3. What is inertia?
4. Can action and reaction balance each other?
5. How does one climb up a rope?
6. Why cannot we walk in space?
7. What does rate of change of momentum represent?
8. Why do we continuously paddle to keep the cycle moving?
9. Why does a scooter tend to skid while executing a sharp turn?
10. Which one would have more inertia : 10 kg mass & 5 kg mass?

Two Marks questions

1. Explain the functioning of shockers in cars.
2. How much force is needed to pull an object of mass 40 kg in vertically upward direction with acceleration of 2.2 m / s².
3. Why does a fan keep moving for sometime when switched off?
4. What do you mean by conservation of momentum?
5. Inflated balloon lying on the surface of a floor moves forward when pricked with a pin. Why?

Three Marks questions

1. An iron sphere of mass 10 kg is dropped from a height of 80 cm, if ‘g’ = 10 m / s². Calculate the momentum transferred to the ground by the body.
2. What would be the force required to stop a car of mass 1000 kg and a loaded truck of mass 10,000 kg in 2 seconds each moving with velocity 5 m / s.
3. Deduce law of conservation of momentum using third law of motion.

Five Mark questions

1. Name and define three different types of inertia & give an example of each.

Chapter 8 : “Motion”

KEY CONCEPTS [ ^[1]rating as per the significance of concept ]

1	Motion	****
2	Graphical Representation of Motion & Graphs	***
3	Equation of motion	****
4	Uniform Circular Motion	**

1 Motion (Uniform Motion And Non Uniform Motion, Acceleration and Velocity)

• A particle is a point-like object, has mass but infinitesimal size
• The object’s position is its location with respect to a chosen reference point, In the diagram, the road sign the reference point
• Motion occurs when an object changes its position.

Both Distance and Time are important in describing motion.

• Sometimes you know motion has occurred even if you didn’t see it happen. (mail truck)
• Relative motion: when two objects are moving in a plane (either in same direction or opposite) each have relative motion with respect to second. e.g. a person sitting in a train and watching a tree, in this case tree is stable but is assumed to be moving but with respect to train.

Distance vs. Displacement

• Distance: How far an object has moved. It has only magnitude without direction. (total)
• Displacement: How far and in what direction an object has moved from its start position. i.e. the direct distance between two points.

Speed

• Speed = the distance an object travels in a given amount of time

. distance

• Speed =

time

Types of Speed

• Constant speed: speed doesn’t change (set your car on cruise control)
• Changing speed: Riding a bike for 5 km. Take off and increase speed, slow

down up hill, speed up down hill, stop for stop sign. The trip took you 15 min

(.25 h)

. total distance

• Average speed:

^c total time

• Instantaneous speed: speed at any given time.

Velocity

• Velocity: includes speed and DIRECTION
• Storm is moving at 20km/hr.
• Should you be seeking shelter?
• Suppose two trains are going with the same speed in opposite direction so they are having different velocities.
• Race car going around an oval track might have constant speed, but different velocities at each point.

Acceleration

• Any change in velocity over a period of time is called acceleration.
• The sign (+ or -) of indicates its direction. + sign shows the acceleration and – sign shows de-acceleration.
• Uniform (constant) acceleration equation
• a = v/t

• Images of car are equally spaced.
• The car is moving with constant positive velocity (shown by red arrows maintaining the same size) .
• The acceleration equals to zero

• Images of car become farther apart as time increases
• Velocity and acceleration are in the same direction
• Acceleration is uniform (Arrows below the car maintain the same length)
• Velocity is increasing (Arrows above the car are getting longer)
• This shows positive acceleration and positive velocity

Galileo Galilei Italian physicist and astronomer

Formulated laws of motion for objects in free fall

• A freely falling object is any object moving freely under the influence of gravity

alone.

• It does not depend upon the initial motion of the object
• Dropped – released from rest
• Thrown downward
• Thrown upward
• The acceleration of an object in free fall is directed downward, regardless of the initial motion
• The magnitude of free fall acceleration (gravitational acceleration) is g = 9.80 m/s²
• g decreases with increasing altitude
• g varies with latitude, height and depth from earth surface.
• 9.80 m/s² is the average at the Earth’s surface
• The italicized g will be used for the acceleration due to gravity
• Not to be confused with g for grams

With negligible air resistance, falling objects can be considered freely falling. objects of different shapes accelerate differently (stone vs feather)

Speed both upward and downward

Test Yourself:

1. Give the equation for uniform motion.
2. When a car stops after applying brakes, what is the final velocity?
3. Uniform Circular Motion

In this kind of motion the object moves on circle with fix speed but the direction is changed by the time so the velocity of the change so its called acceleration motion. This acceleration is called centrifugal acceleration. It is directed toward the centre.

Test Yourself:

1. What remains constant in uniform circular motion?
2. What changes continuously in uniform circular motion?

QUESTION BANK

One Mark questions

1. Can displacement be zero even when distance is not zero?
2. Can the distance travelled by an object be smaller than magnitude of its displacement?
3. A particle is moving with uniform velocity. What is its acceleration?
4. How can you get speed of an object from its distance – time graph?
5. How can you get distance of an object from its speed – time graph?
6. A brick & an elephant are in free fall. What is common in their motion?
7. When an object is thrown vertically upwards. What is its velocity at the highest point?
8. Can velocity & acceleration point in opposite directions?
9. Define acceleration.
10. What is non uniform motion?

Two Marks questions

1. Differentiate scalars & vectors?
2. What is retardation? How does it affect the speed?
3. Can speed of a body vary with its velocity constant? Explain.
4. Why is circular motion with constant speed called accelerated motion?
5. State the difference between distance & displacement.
6. What is the difference between speed & velocity?
7. What does a speedometer & odometer indicate?

Three Marks questions

1. If an object is thrown vertically upwards with speed 49 ms^-1. How long does it take to complete upward journey? What maximum height does it achieve?
2. An object starting from rest covers 20 metres in first 2 seconds & 160 metres in next 4 seconds. What is its velocity after 7 seconds from the start?

Five Marks questions

1. Derive all the three equations of motion for uniform acceleration using graphical method.
2. A car a moving at rate of 72km/h and applies brakes which provide a retardation of 5ms^-2.
3. How much time does the car takes to stop.
4. How much distance does the car cover before coming to rest?
5. What would be the stopping distance needed if speed of the car is doubled?

1. sI unit of speed is m/s ↑

Chapter 7: “Diversity in Living Organisms”

KEY CONCEPTS : [ *rating as per the significance of concept]

CONCEPTS	RATING
Basis of classification	***
Hierarchy of classification	****
Kingdom Plantae	*****
Kingdom Animalia	*****

1. Each organism is different from all other organisms.
2. In this activity, we decide which characteristics (we can run, but the Banyan tree can’t run is a characteristic) are important in forming the desired category.
3. Greek thinker Aristotle classified animals according to whether they lived on land, in water or in air. This classification is a landmark in ideology, but has limitations. For example, animals that live in the sea include Corals, Whales, Octopus, Starfish, and Shark. In fact they are different from each other.
4. Classification and Evolution: organisms are classified based on body design, hierarchy in developing, relation to evolution. Charles Darwin first described the idea of evolution in 1859 in his book ” The Origin of Species”
5. The Biologists, such as Haeckel, Whittaker & Carl Woese tried to classify all living organisms into broad Kingdoms. The Whittaker proposed five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. Carl Woese introduced by dividing Monera into Archaebacteria and Eubacteria.

1. Monera: They have unicellular, Prokaryotic organisms (do not have defined nucleus or organelles). The cell wall may or may not present. The mode of nutrition is autotrophic (synthesizing food on their own) (or)heterotrophic (getting food from environment). Ex. Bacteria, Anabaena. ( (Please refer to Fig. 7.1 Monera NCERT Book Page-83)
2. Protista: They have unicellular eukaryotic organisms (do have well defined nucleus or organelles). The body is covered by cilia, flagella for locomotion. The mode of nutrition is autotrophicorheterotrophic. Ex. Diatoms, protozoans.(Please refer to Fig. 7.2 NCERT Book Page-84)
3. Fungi: These are multi-cellular eukaryotic organisms with cell wall, made up of Chitin. They do not perform Photosynthesis (heterotrophic), Saprophytic (derive nutrition from decaying material). Ex. Aspergillus, Penicillium, Mushroom, Rhizopus. The fungi living with algae forms Lichen (Symbiotic Association) .(Please refer to Fig. 7.3 NCERT Book Page-84).
4. Plantae: These are multi-cellular eukaryotic organisms with cell wall, made up of Cellulose. Able to perform photosynthesis (autotrophic). Ex. Rice, wheat.
5. Animalia: These are multi-cellular eukaryotic organisms without cell wall. They are not able to perform photosynthesis (heterotrophic). Ex Human beings, Peacock.

(Please refer to Fig. 7.4 NCERT Book Page-85).

DETAILS OF KINGDOM PLANTAE

1. The kingdom Plantae is further classified as Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, Angiosperms .
2. Thallophyta: The plants do not have well defined body design, commonly called as” Algae”, mostly aquatic. Ex. Spirogyra, Ulothrix. (Please refer to Fig. 7.5 NCERT Book Page- 86).
3. Bryophyta: These are commonly called as the “Amphibians of Kingdom”. The plant body is differentiated into roots like, stem like and leaf like structures. No specialized tissues for the conduction of water and food.Ex. Marchantia, Funaria. (Please refer to Fig. 7.6 NCERT Book Page-86).
4. Pteridophyta: These are commonly called as the “First vascular land plants “. The plant body is differentiated into root, stem and leaf. Specialized tissues for the conduction of water and food are developed in these plants. The reproductive organs are inconspicuous. Ex. Marsilea, Fern. (Please refer to Fig. 7.7 NCERT Book Page-87).

Special Note: The reproductive organs are inconspicuous in Thallophyta, Bryophyta, Pteridophyta are can’t develop seeds. They are together called as” Cryptogamae (NonFlowering Plants)”. The plants with well differentiated reproductive organs and that ultimately make seeds are called” Phanerogams (Flowering Plants)”. This group is further classified Gymnosperms (Bear naked Seeds) &Angiosperms (Bears seeds inside Fruit).

1. Gymnosperms: These are commonly called as “Naked seed bearing plants”. They areusually perennial, evergreen and woody. Ex. Pinus, Cycas (Please refer to Fig. 7.8 NCERT Book Page-87).
2. Angiosperms: These are commonly called as “Enclosed seed bearing plants”. Plants with seeds having a single cotyledon are called as” Monocotyledons or Monocots”. Plants with seeds having two cotyledons are called as “Dicots”. Ex. Ipomoea, Paphiopedium.

(Please refer to Fig 7.9 &. 7.10 NCERT Book Page-87 ;Fig. 7.11 Page-88).

DETAILS OF KINGDOM ANIMALIA

These are Eukaryote, multicultural and hetero-tropic.

They are further classified as Non- Chordates( Porifera, Coelenterata, Platyhelminthes , Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata) and Chordates { Protochordata, Vertebrata ( Pisces, Amphibians, Reptilia, Aves, Mammalia)} .

I.Non- Chordates

1. Porifera: The word Porifera” means organisms with holes”. The canal system helps in circulating water, food, oxygen. They are non-motile with cellular level of organization and mainly marine organisms with hard outer coat called as Skeleton. They are commonly called as Sponges. Ex. Spongilla, Sycon( Please refer Fig. 7.12, NCERT Text Book Page- 89)
2. Coelenterata: The wordCoelenterata” means organisms with body cavity

calledCoelenteron” . They are radially symmetrical, Diploblastic ( two layers of cells), commonly called as Cnidarians ( Stinging cells for protection are present in the body). Ex. Hydra, Sea Anemone (Please refer Fig. 7.13, NCERT Text Book Page- 89).

1. Platyhelminthes: The word Platyhelminthes means organisms with flatworms ( dorsocentrally flattened)”.They are bilaterally symmetrical Triploblastic ( three layers of cells ), either free-living or parasitic. No true Coelom is present – Acoelomates. Ex. Planaria( Free living) , Tape worm( Parasitic)( Please refer Fig. 7.14, NCERT Text Book Page- 90).
2. Nematoda: The word Nematoda “means organisms with roundworms”. They are bilaterally symmetrical Triploblastic ( three layers of cells ), familiar with parasitic worms. The false Coelom is called as Pseudocoelome. Ex. Ascaris, Wuchereria (Filarial worm causes elephantiasis).)( Please refer Fig. 7.15, NCERT Text Book Page- 90).
3. Annelida: The word Annelida ” means organisms with metameric-segmented”. They are bilaterally symmetrical Triploblastic(three layers of cells) with closed circulatory system, familiar with earth worms. The Coelom is called as true Coelom. Ex. Neris, Earth worm, Leech (Please refer Fig. 7.16, NCERT Text Book Page- 90).
4. Arthropoda: The word Arthropoda “means organisms with jointed legs” They are bilaterally symmetrical Triploblastic(three layers of cells ), familiar with cockroaches. The Coelom is blood filled called as Haemo Coelom. Ex. Prawn, Scorpion, Housefly (Please refer Fig. 7.17, NCERT Text Book Page- 91).
5. Mollusca: The word Mollusca “means organisms with soft body” They are bilaterally symmetrical, Triploblastic(three layers of cells), familiar with Octopus, Pila. Foot is for moving, kidney like organ for excretion, with open circulatory system. Ex. Unio, chiton( Please refer Fig. 7.18, NCERT Text Book Page- 91).
6. Echinodermata: The word Echinodermata “means organisms with spiny skinned”. Exoskeleton is with calcium carbonate. They are radially symmetrical Triploblastic ( three layers of cells ) with coelomic cavity, familiar with Star fish. They are exclusively free-living marine animals. Ex. Sea Cucumber, Feather Star (Please refer Fig. 7.19, NCERT Text Book Page- 91).
7. Chordates: They are further classified as two major groups such as Protochordata& Vertebrata
8. .Protochordata: Notochord present in at least larval forms, but very rudimentary. It is a

rod like supporting structure, runs along with nervous tissue from the gut of animal. They are bilaterally symmetrical, triploblastc(three layers of cells) with a Coelom, familiar with Amphioxus. Ex. Balanoglossus(Please refer Fig. 7.20, NCERT Text Book Page- 92).

1. .Vertebrata: Notochord is replaced by vertebral column and internal skeleton. They are bilaterally symmetrical, triploblastic, coelomic and segmented having paired gill pouches. Vertebrates are grouped into five classes.
2. Pisces: These are commonly called as “fishes”, exclusively aquatic. Body is streamlined and a tail for locomotion. Gills for respiration, heart is two chambered, cold blooded, skin is covered with scales, plates. They are cold-blooded animals. Skeleton of bone ( Rohu) / cartilage( Shark). They lay eggs. Ex. Lion Fish, Dog Fish (Please refer Fig. 7.21, NCERT Text Book Page- 92).
3. Amphibians: These are commonly called as “Amphibians” because they can live on land and in water”. Body is streamlined and a webbed foot/ foot for locomotion. Gills or lungs or skin for respiration, heart is three chambered, cold blooded, skin is lack of scales, plates. They are cold-blooded animals. They lay eggs. Ex. Rana, Hyla (Please refer Fig. 7.22, NCERT Text Book Page- 93).
4. Reptilia: These are commonly called as “Reptilians”. A lung for respiration, heart is three chambered (Crocodile heart is four chambered), skin have scales. They are cold-blooded animals. They lay eggs. Ex. Snakes, Turtles (Please refer Fig. 7.23, NCERT Text Book Page- 93).
5. Aves :These are commonly called as “Birds”. A lung for respiration, heart is four chambered, fore limbs are modified for flight, skin has feathers. They are warm-blooded animals. They lay eggs. Ex. Ostrich (Flightless Bird), Pigeon, Sparrow (Please refer Fig. 7.24, NCERT Text Book Page- 94).
6. Mammalia: These are commonly called as “animals with mammary glands for producing milk to nourish their young ones”. A lung for respiration, heart is four chambered, skin has hairs, sweat or oil glands. They are warm-blooded animals. They lay eggs (Platypus, Echidna), give birth to young ones poorly developed (Kangaroo) & give birth to developed young ones (Human beings). Ex. Lion, Whale, Bat (Please refer Fig. 7.25, NCERT Text Book Page- 94& Fig.7.26, classification of Animals, Page- 95).

DETAILS OF NOMENCLATURE

NOMENCLATURE: The system of scientific naming or nomenclature was introduced by Carolus Linnaeus. It is unique to identify in the world. We limit ourselves to writing the names of the Genus and Species of that particular organism. The world over, it has been agreed that both these names will be used in Latin forms.When printed is given in italics and when written by hand, the Genus and Species name have to be underlined separately. Ex. Ostrich (Common name): Struthiocamelus(scientific name with two parts namely the Genus and Species).

QUESTION BANK

1. What is the book written by Charles Darwin? (The Origin of Species)
2. Who proposed the five kingdoms such as, Monera, Protista, Fungi, Plantae and Animalia? (Whittaker)
3. Monera members areunicellular, Prokaryotic organisms, mention TRUE/ FALSE (TRUE)
4. The Diatoms belongs to the kingdom ( Protista)
5. TheAnabaena belongs to the kingdom (Monera)

6 are commonly called as the”Amphibians of Plant Kingdom”.( Bryophyta)

1. The warm-blooded animals with fore limbs modified for flight, skin has feathers are called

as (Aves/Birds)

1. Write the four salient features of Reptiles.
2. Compare the Pisces and Amphibians.

10..Write the five salient features of Mammalia, give two examples.

QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

Time: 90 minutes

Marks- 40

* General Instructions

1. Questions 1-5 (1 Mark each)
2. Questions 11-15 (3Mark each)
3. Questions 6-10 ( 2 Mark each)
4. . Questions 16-17 (5Mark each)

Q.1 Anabaena is member of the Phylum

Q.2 Aspergillum is a member of the Phylum

Q.3 Define the term Autotrophic mode of nutrition

Q.4 The fungus living with algae is called as

Q.5 Name the scientist who has divided the Monera into two sub-groups

Q.6 Draw and label Paramecium.

Q.7 Distinguish the meaning of terms Gymnosperms and Angiosperms.

Q.8 What is Pseudocoelome? Give one example of it.

Q.9 What is Haemocoelome? Give one example of it.

Q.10 Write two salient features of mammalian group.

Q.11 What is the basis of nomenclature of organisms, give the scientific name of Ostrich. Q.12 Give three salient features of Amphibia.

Q.13 Mention three features of Chordates.

Q.14. Draw and label Balanoglossus.

Q.15 Give two salient features of Aves and mention one example of a flightless bird. Q.16 Write about the Hierarchy of Classification- Groups and mention basic unit of classification.

Q.17 Give the salient features of Bryophytes and draw the diagram of Funaria.

Chapter 5: “The Fundamental Unit of Life”

KEY CONCEPTS : [ *rating as per the significance of concept]

CONCEPTS	RATING
Study of historical perceptive related to cell discovery
Study of Microscope	**
Study of Hypotonic/Isotonic/ Hypertonic solutions relation to osmosis.	****
Cell wall	***
Nucleus	*****
Cytoplasm	***
Cell organelles	*****

1. All the living organisms are made up of fundamental unit of life called” cell”.
2. The cell is a Latin word for “a little room”.
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) resembled the structure of a honeycomb. The use of the word “Cell” to describe these units is used till this day in Biology as” Cell Biology”.
4. The Compound Microscope consist eye piece,objective lens and condenser to observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( father of microbiology)
6. The scientist Robert Brown discovered the nucleus in the cell.
7. The cell theory states that all the plants and animals are composed of cells, it was proposed by Schleiden and Schwann.
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise from the pre-existing cells”.
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm etc. Each kind of cell performs specific function.
10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, Paramecium and Bacteria; these are called as unicellular organisms. Whereas in multi-cellular organisms (Human beings) division of labor is seen.
11. The feature in almost every cell is same: Plasma membrane, nucleus and cytoplasm.
12. Plasma membrane: It is the outermost covering of the cell.

• It is called as selective permeable membrane (because it prevents movement of some materials).
• It helps in diffusion and osmosis
• Diffusion: movement of substance from high concentration to low

concentration.

Eg; exchange of carbon dioxide or oxygen with external environment.

osmosis: it is the passage of water from the region of high water concentration to a region of low water concentration through a selective permeable membrane.

1. The cell gains water, if the medium surrounding the cell has a higher water concentration (Hypotonic solution) than the cell.
2. The cell maintains the same water concentration as the cell (Isotonic solution), water crosses the cell membrane in both directions.
3. The cell loses water, if the medium has lower water concentration (Hypertonic solution) than the cell.

Note – The cell drinking is endosmosis;

• omission of water is called ex-osmosis.

ENDOCYTOSIS EXOCYTOSIS

1. The cell engulfs food is called endocytosis and ejects solid is called exocytosis. Amoeba acquires food through endocytosis and excretion of solid is called exocytosis.
2. The cell wall is a rigid outer covering composed of cellulose. It provides structural strength to plant cells. When a living cell loses water, there is shrinkage of contents of a cell away from the cell wall. This phenomenon is called as plasmolysis. The cell walls permit the cells of plants, fungi and bacteria to withstand very dilute (Hypotonic) external media without bursting.
3. The Nucleus: It is a dark colored, spherical or oval, dot-like structure near the center of a cell called Nucleus. The nucleus plays a central role in cellular activities/ reproduction. The chromatin material gets organized into chromosomes. The chromosomes contain information for inheritance of features from parents to next generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein molecules. The functional segments of DNA are called genes.
4. In some organisms like Bacteria nucleus is not covered by nuclear membrane. Hence it is called as prokaryote. (Pro= primitive; karyote = karyon = nucleus.) The organisms with cells having a nuclear membrane are called eukaryotes.
5. Differences between prokaryotes and eukaryotes( Please refer to Fig. 5.4: Prokaryotic cell NCERT Book Page-62)

Prokaryotes	Eukaryotes
Size: generally small (1-10 |am)	Size: generally large. (5-500 |am)

Nuclear region: Not well defined and not surrounded by a nuclear membrane & known as nucleoids.	Nuclear region: Well defined and surrounded by a nuclear membrane
Chromosome: Single	Chromosome: More than one chromosome
Membrane-bound cell organelles absent	Membrane-bound cell organelles present
Eg- bacteria, blue green algae	Eg fungi, plant cell and animal cell.

1. Cell organelles: Every cell has fluid matrix (other than nucleus) is called cytoplasm. The nucleus and cytoplasm is together called as protoplasm. The protoplasm term was coined by Purkinje. It has important cell organelles: Endoplasmic Reticulum (ER), Golgi apparatus, Lysosomes, Mitochondria, Plastids, and vacuoles.
2. Endoplasmic Reticulum (ER): It is a large network of membrane -bound tubules and vesicles.

• There are two types of Endoplasmic Reticulum
• Rough Endoplasmic Reticulum (RER) (It looks rough because Ribosomes are attached to its surface. They are the sites of protein synthesis).
• Smooth Endoplasmic Reticulum (SER) (It looks smooth because Ribosomes are not attached to its surface. They are the sites of fat molecules synthesis).

1. SER ; help in the functioning of enzymes and hormones to carryout biochemical activities.
2. SER detoxifies many poisons and drugs from the cell.
3. ER serves as channel for the transport of material between various regions of the cytoplasm and the nucleus.
4. Proteins and fat molecules produced by ER helps in membrane biogenesis.
5. Golgi apparatus: It was first described by a scientist Camillo Golgi. It is a system of membrane bound vesicles called cisterns. It functions include the storage,

modification and package of cell products. The complex sugars are made from simple sugars in the Golgi apparatus. It is also involved in the formation of lysosomes.

1. Lysosomes: They contain membrane-bound sacs with powerful digestive enzymes (enzymes are made by RER) to digest the worn-out cell organelles. When the cell gets damaged, lysosomes may burst and the enzymes digest their own cell, hence called as “Suicidal bags of a cell”. It is a waste disposal system of the cell.
2. Mitochondria: It is covered by a double membrane. Outer membrane is very porous and the inner membrane is deeply folded. These folds create a large surface area for ATP (Adenosine Triphosphate) molecule synthesis. ATP is the energy currency of a cell; hence the Mitochondria are called as Power House of a Cell. Mitochondria have their own DNA and Ribosomes; therefore they can make their own proteins.
3. Plastids: They are present only in plant cells. They are two types.
4. Chromoplasts (Colored Plastids: Chloroplasts – Green pigmented and useful in Photosynthesis and also contains various other pigments like yellow or orange)
5. Leucoplasts (White or colorless plastids; stores materials such as oils, proteins, fats etc. ) Plastids are also covered by a double membrane. The matrix is called Stroma, seat for enzymatic actions. Plastids have their own DNA and Ribosomes; therefore they can make their own proteins.
6. Vacuoles: Storage sacs for solid or liquid contents. They are small in size in animals while plants have large, may occupy 50-90 % of the cell volume. Helps to provide turgidity and rigidity to the cell. Many substances like amino acids, sugars, organic acids and proteins are stored in vacuoles. In Amoeba food vacuole is specialized to play an important role.
7. Cell: It is the fundamental structural unit of living organisms, helps in respiration, obtaining nutrition and clearing waste material or forming a new protein.

Differences between Plant cell and Animal Cell

(Please refer to Fig. 5.5 Animal cell & 5.6: Plant cell NCERT Book Page-63&64)

ANIMAL CELL	PLANT CELL
Cell wall absent	Cell wall present
Plasma membrane is the outer layer which provides turgidity to the cell	Cell wall is the outer layer which gives rigidity and turgidity to the cell
Vacuoles are small in size	Vacuoles are big in size
Plastids are absent	Plastids are present
Nucleus lies in the centre.	Nucleus lies on one side

Question Bank

1. All the living organisms are composed of fundamental unit called as ( Cell)
2. Who discovered the nucleus in the cell ( Robert Brown)
3. Who saw the free living cells for the first time ( Leeuwenhoek)
4. Name two unicellular organisms ( Amoeba, Chlamydomonas,)
5. Write two differences between prokaryotes and eukaryotes ( Nuclear

region/ Chromosome)

1. What are the two types of ERs ( RER/ SER)
2. What are the functions of Golgi Bodies? (It includes the storage, modification and

package of cell products. The complex sugars are made from simple sugars in the

Golgi apparatus).

1. What are the types of plastids (Chromoplasts& Leucoplasts)
2. Which are the substances stored in vacuoles? (Substances like amino acids, sugars, organic acids and proteins are stored in vacuoles)
3. Draw and label Animal cell & Plant cell( Ref NCERT Book Page-63&64)

QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

Time: 90 minutes

Marks- 40

* General Instructions

1. Questions 1-5 ( 1 Mark each)
2. Questions 11-15 ( 3Mark each)
3. Questions 6-10 ( 2 Mark each)
4. . Questions 16-17 ( 5Mark each)

Q.1 What is ATP, expand the term

Q.2 Cellulose is a Fat (Mention,True/False)

Q.3 Which cell organelle is synthesizing the enzymes for the Golgi Apparatus

Q.4 The flexibility of the cell membrane to engulf food and other material is called

Endocytosis (Mention, True / False)

Q.5 What is the main function of Leucoplasts?

Q.6 Draw the structure of Ovum.

Q.7 Why the Plasma membrane is called as Selective Permeable Membrane?

Q.8 Describe what is an isotonic solution Q.9 What is Plasmolysis?

Q.10 Write any two parts of a Compound microscope.

Q.11 Distinguish between Prokaryotic and Eukaryotic Cell.

Q.12 Write about the three properties of Cytoplasm.

Q.13 What is the significance of Vacuoles Q.14 Write a short notes on Mitochondria.

Q.15 Explain the concept of diffusion.

Q.16 Draw the structure of a plant Cell and label it.

Q.17 Write the differences between a plant and animal cell.

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