Synopsis – Grade 9 Science Term I
Chapter 1: Matter in Our Surroundings
Characteristics of matter particles
There are spaces between matter particles
Matter particles move continuously – movement increases with rising temperature
Attract each other – decreasing order of force of attraction: solids > liquids > gases
Solid phase: Have permanent shape, size and boundary with negligible compressibility
Liquid phase: Have a fixed volume with low compressibility but no fixed shape
Gaseous state: Have high compressibility with no fixed shape, volume, and boundary
Boiling point: temperature at which the vapour pressure becomes equal to the
atmospheric pressure. It can also be referred to as the temperature at which a liquid
changes to its vapours.
Melting point → Temperature at which a solid melts into a liquid at normal atmospheric
pressure.
Effect of change of pressure
If pressure is applied,
Melting point decreases
Boiling point increases
Latent heat → Heat required for breaking the force of attraction between the particles at
transition temperature.
Amount of heat required to change 1 kg of material to change its state at normal
atmospheric pressure at transition temperature is called the latent heat for that
transition.
Dry ice → Solid carbon dioxide
Sublimation → Process of changing of a solid to its gaseous form
Evaporation → Change of liquid into vapours at any temperature below the boiling
point. Takes the latent heat from body. Thus, the body cools when evaporation takes
place.
Factors affecting evaporation
Surface area If increases, rate of evaporation increases
Temperature If increases, rate of evaporation increases
Humidity If increases, rate of evaporation decreases
Wind speed If increases, rate of evaporation increases
Chapter 2: Is Matter around Us Pure
Mixture – Contains more than one pure substance in any ratio/proportion
Substance – Cannot be separated into its constituent particles by any physical process
Solution – Homogeneous mixture of two or more substances
Alloys – Homogeneous mixture of metals
Properties of solution:
Homogeneous mixture
Particles are extremely small, not visible to the naked eye
Light path not visible
Solute particles cannot be separated by filtration
Concentration of solution = Solute amount / Solvent amount
Mass by mass percentage = 100Solute mass
Solution mass
Mass by volume percentage = 100Solute mass
Solution volume
Suspension – Heterogeneous mixture of solids and liquids where the solid particles
suspend throughout the medium. Example: Mixture of chalk powder and water
Properties of suspension
o Particles are visible to the naked eye
o Light path visible
o Particles settle down
Colloidal solution- Is a heterogeneous mixture, but appears to be homogeneous.
Example: milk
Properties of colloidal solution
o Heterogeneous mixture
o Particle size is small, not visible to the naked eye
o Light path can be visible
o Particles do not settle down
o Substances cannot be separated by filtration
Tyndall effect → Scattering of light beam by suspended particles in the solution
Separation processes
Evaporation – Used for separating mixture of volatile solvents and non-volatile
solutes. Example: Separating salt from its solution
Centrifugation – Used for separating components based upon the difference in their
weights. Example: Separating mixtures of cream from milk
Separating funnel – Used for separating two or more immiscible liquids. Example:
Separating oil and water
Sublimation process – Used to separate sublimable solids from their mixtures.
Example: Separating ammonium chloride from a mixture
Chromatography – Used to separate those solutes that dissolve in the same solvent.
Example: Separating the components of a dye
Distillation – Used to separate two miscible liquids that boil without decomposition.
Example: Separating a mixture of acetone and water
Fractional distillation – Used to separate a mixture of liquids when the boiling
temperature difference is less than 25 K. Example: Separating different components
of petroleum
Crystallization – Used to separate pure solids from a solution by forming crystal.
Example: Obtaining pure crystals of copper sulphate from an impure sample
Differences between a mixture and a compound
Mixture Compound
No new compound New compound
Elements or compounds mix Elements react
Properties of constituents remain unchanged New substance has totally new properties
A constituent can be separated easily by
physical methods
Can be separated by chemical methods or
electrolysis
Chapter 3: The Fundamental Unit of Life
Cell: It is the smallest unit of life capable of performing all living functions.
On the basis of cell number, organisms are divided into two types:
Unicellular organism: made up of only a single cell, e.g. Amoeba, Paramecium
Multicellular organism: made up of many cells, e.g. algae, plants, animals, etc.
Structural organization of cell
Cell wall: Outermost structure present in plant, fungal and some bacterial cells;
absent in animal cells
Plasma membrane or cell membrane: Outermost covering of all cells. It separates
the contents of the cell from the external environment.
Important functions of cell membrane:
Regulates the entry and exit of substances in and out from the cell
Performs certain physical activities such as diffusion and osmosis
o Diffusion: The spontaneous movement of molecules from a region of high
concentration to a region of low concentration
o Osmosis: The movement of water molecules from a region of high concentration
to a region of low concentration, through a selectively permeable membrane
Cytoplasm: It is the fluid that fills the cell; It contains all cell organelles
Cell organelles
Nucleus: It controls all the cellular activities of the cell; acts like the brain of a cell.
Important components of nucleus:
o Nuclear membrane
o Nucleoplasm, containing chromatin
o Nucleolus
Prokaryotic cell - The nuclear region is poorly defined; membrane-bound organelles
are absent. The undefined nuclear region containing only nucleic acid is called
nucleoid.
Eukaryotic cell – Nuclear region is bounded by nuclear membrane; membrane-bound
organelles are present
Endoplasmic reticulum – It helps in the synthesis and packaging of proteins and
lipids. SER plays a significant role in detoxifying many poisons and drugs. It is of two
types;
o SER - Smooth (due to absence of ribosomes) endoplasmic reticulum
o RER - Rough (due to presence of ribosomes) endoplasmic reticulum
Ribosome: Site of protein synthesis
Golgi apparatus: It is known as dictyosomes in plant cells
o Helps in the storage, modification, and packaging of products in vesicles
o Involved in the formation of lysosomes and peroxisomes
Lysosome: It contains digestive enzymes that can destroy any foreign material; also
known as the ‘suicidal bag’ of a cell
Mitochondria - It is known as the ‘powerhouses of the cell’;
o It is a double membrane bound organelle that have their own DNA; hence they are
able to make some of their own proteins
o Involved in cellular respiration
o Produce energy in the form of ATP (Adenosine triphosphate). Hence, it is also
known as energy currency of the cell.
Plastids: It is present only in plant cells. These are also double-membraned structures
having their own DNA and ribosome. They are of two types;
o Chromoplasts (coloured plastids): It include chloroplasts which are important for
photosynthesis in plants
o Leucoplasts (white or colourless plastids): It help in the storage of carbohydrates
(starch), fats, and proteins
Vacuole: It is found in both plant and animal cells. It is single and large in plant cells
while it is small and numerous in animal cells.
Important functions of vacoules:
o Provide turgidity and rigidity to plant cells
o Store some useful substances like amino acids, sugars, various organic acids etc.
o In some organisms specialised vacuole performs the function of expelling waste
material and excess of water.
Differences between plant and animal cells
Animal cell Plant cell
Generally small in size
Cell wall is absent
Plastids are absent
Vacuoles are present in
abundance and smaller in size
Usually larger than animal cells
Cell wall is present
Plastids are present
Vacuoles are usually single and
larger in size
Milestones in Cell Biology
Biologists Major contributions
Robert Hooke Discovered cell
Leeuwenhoek Discovered microscope
Robert Brown Nucleus
Purkinje Coined term protoplasm
Schleiden and Schwann Presented Cell theory
Camillo Golgi First described Golgi apparatus
Cell theory
All plants and animals are composed of cells
The cell is the basic unit of life.
All cells arise from pre-existing cells.
Chapter 4: Tissues
Tissues: Group of cells that work together to perform a particular function
Plant tissues
On the basis of the dividing capacity, plant tissues are of two types: Meristematic and
permanent tissue.
Meristematic tissues: It consists of actively-dividing cells. They are of three types;
o Apical meristem: Present at the growing tips of stems and roots. Its function is to
increase the length of stems and roots
o Intercalary meristem: Present at the base of leaves or internodes. Required for
the longitudinal growth of plants
o Lateral meristem: Present on the lateral sides of the stems and roots. Its function
is to increase the thickness of stems and roots.
Permanent tissues: Formed from meristematic tissues. The cell loses the ability to
divide. Divided into two types
Simple permanent: Consist of only one type of cells. There are three types;
o Parenchyma: Composed of unspecialised loosely packed living cells with
relatively thin cell walls.
o Parenchyma that contains chloroplast and performs photosynthesis is called
chlorenchyma.
o Parenchyma that contains large air cavities is called aerenchyma. These large air
cavities provide buoyancy to aquatic plants.
o Collenchyma - Composed of living and elongated cells with cell walls irregularly
thickened at the corners; have very little intercellular spaces; provide flexibility
and mechanical support to the various parts of the cells.
o Sclerenchyma - Composed of long, narrow, and lignin deposited thick-walled
cells. This tissue is made up of dead cells and there are no intercellular spaces. For
example, husk of coconut.
o Protective tissues: Protects the plant from external injuries. The two types of
protective tissues are epidermis and cork
Complex permanent - Made up of more than one type of cell. These tissues
constitute vascular bundles. They are of two types;
o Xylem
Conducts water and minerals from the roots to the different parts of the plant
Composed of four different types of cells; tracheids, vessels, xylem parenchyma,
and xylem fibres. Except xylem parenchyma all other xylem elements are non-
living.
o Phloem
Conducts food material from the leaves to the different parts of the plant
Composed of four different types of cells; sieve tubes, companion cells, phloem
parenchyma, and phloem fibres. Except for phloem fibres, all other phloem cells
are living.
Animal tissues
Animal tissues are classified into four types based on the functions they perform:
Epithelial, Connective, Muscular and Nervous tissue.
Epithelial tissues: Tightly packed cells with almost no intercellular spaces. It forms
the covering of the external surfaces, internal cavities, and organs of the animal body.
They are of four types;
o Squamous epithelium: Single layer of extremely thin and flat cells are called
simple squamous epithelium while multi layered cells forms stratified
squamous epithelium.
o Simple squamous epithelium: Lining of the mouth, oesophagus, lung alveoli, etc.
Stratified squamous epithelium: Skin
o Cuboidal epithelium: Consists of cube-like cells. Found in the lining of kidney
tubules and ducts of the salivary glands
o Columnar epithelium: Consists of elongated or column-like cells. Found in the
inner lining of the intestine and gut
o Glandular epithelium: Consists of multicellular glands
Connective tissues: Specialised to connect various body organs. Various types of
connective tissues are:
o Areolar tissue: Found in the skin and muscles, around the blood vessels, nerves,
etc.
o Adipose tissue: Acts as the storage site of fats; found between the internal organs
and below the skin; acts as an insulator for the body
o Dense regular connective tissue: Main components are tendons and ligaments.
Ligaments: Connective tissues which connects a bone to a bone. It is very elastic
Tendons: Connective tissue which connects a bone to a muscle. It has limited
flexibility
o Skeletal tissue: The main component of skeletal tissues are cartilage and bone
o Fluid tissue: Blood is the vascular tissue present in animals. It is composed of
plasma, Red blood cells (RBC), White blood cell (WBC) and platelets.
Muscular tissues: The main function of muscular tissue is to provide movement to
the body. It is of three types
o Striated muscles or skeletal muscles or voluntary muscles: Cells are
cylindrical, un-branched, and multinucleate. Found in our limbs.
o Smooth muscles or involuntary muscles: Cells are long, spindle-shaped, and
possess a single nucleus. Found in oesophagus, iris of the eyes, in ureters.
o Cardiac muscles or involuntary muscles: Cells are cylindrical, branched, and
uninucleate. Found in the heart.
Nervous tissues: Highly specialised tissues present in the brain, spinal cord, and
nerves.
o Neuron: It is the functional unit of nervous tissue.
Chapter 5: Motion
Uniform motion – No change in velocity (No change in speed and direction)
Non-uniform motion – Change in velocity with time
Speed Distance covered
=Time taken
Velocity Displacement
=Time taken
Average velocity Initial velocity + Final velocity Total displacement
=2
v u
t
Total time taken
AccelerationFinal velocity Initial velocity
=Time
v u
t
Distance-time graph
Velocity-time graph
Equation of motion
1st equation: v = u + at
2nd equation: s = ut + 21
2at
3rd equation: 2as = v2 – u
2
The motion of an object moving in a circular path is called circular motion.
Chapter 6: Force and laws of motion
Inertia – Tendency of a body to resist any attempt to change its state of motion.
Mass is the measure of inertia, higher is mass, higher is inertia.
Momentum = mass velocity = mv [kg m/s]
First law of motion
A body at rest remains at rest and a body in uniform motion continue its uniform motion
unless an external force is applied.
Second law of motion
Rate of change of momentum Applied unbalanced force
Direction of change in momentum is the same as the direction of unbalanced force
o Numerically,
/
K.
; for K 1
F m v u t
F ma
F ma
o Newton = Unit of force, 21 N =1 kg×1 m / s
Third law of motion
For every action force there is an equal and opposite reaction force.
Conservation of momentum
For a system, momentum remains constant unless an external force acts on it.
A A B B A A B Bm u m u m v m v
Chapter 7: Gravitation
Kepler’s law of planetary motion
First law: Orbits of planets are elliptical.
Second law: Planet covers equal area in equal time intervals
Third law: 3
2 Constant Distance from sun and Orbital period
rr T
T
Universal law of Gravitation
2
GMm
Fr
G = Universal gravitational constant = 6.673 10–11
Nm2 kg
–2
Inverse square law: 2
1F
r
Gravitation is a weak force unless large bodies are involved.
Force of gravitation due to the Earth is called gravity.
Force of gravity decreases with altitude above surface of Earth.
Force of gravity decreases with depth below surface of Earth.
It also varies on surface of Earth, it decreases from poles to equator.
Force of gravitation explains – motions of moon and planetary tides
The motion of a body in which gravity is the only or dominant force acting upon it is
called free fall.
Value of acceleration due to gravity during free fall is, g =9.8 m/s2, it is independent of
mass of the falling object.
2
2
2
g G
g G 9.8 m / s
M mm
r
M
r
Weight of a body = Earth’s gravitational pull on the body
Weight on moon = 1
6weight on Earth
Tips to solve numerical
For upward motion take g = 9.8ms2
and final velocity at the highest point as 0.
M = Earth's mass
r = Earth's radius
g = Gravitational acceleration
For downward motion take g = 9.8ms2 and for a freely falling body take initial
velocity as 0.
Thrust – Force acting perpendicular to a surface
Pressure = Perpendicular force per unit area 2ForceN / m Pascal Pa
Area
Buoyant force = Up thrust by a fluid on a body immersed in it [Depends on fluid density]
If density of body > density of fluid, then the body will sink in the fluid, and vice
versa
(Density of cork) < (density of water), so cork floats
(Density of iron) > (Density water), so iron sinks
Archimedes’ principle:
Upward force experienced by a body immersed in fluid = Weight of the displaced
fluid
Lactometer is a device to measure purity of milk.
Relative density Density of a substance
Density of water
Chapter 8: Improvement in Food Resources
Improvement in crop yields
The crops grown in rainy season are known as kharif crops. These are grown from the
month of June to October.
Soya bean, paddy, maize, cotton, pigeon pea, green gram, and black gram are kharif
crops.
The crops grown in winter are known as rabi crops. The rabi season is from
November to April.
Wheat, gram, mustard, linseed, and pea are rabi crops.
The variety of the crop can be improved by hybridization and genetic engineering.
Hybridization is the crossing between genetically dissimilar plants. It can be
intervarietal or interspecific.
Genetic engineering is the deliberate insertion or deletion of genes in an organism for
obtaining a better organism.
The net crop yield can also be increased by adopting better cropping pattern(s) such as
inter-cropping, mixed cropping, and crop rotation.
Mixed cropping is growing two or more crops simultaneously on the same piece of
land
Inter cropping is growing two or more crops simultaneously on the same field in a
different pattern.
The growing of different crops on a piece of land in a pre planned succession is called
crop rotation.
Factors for high variety improvement
Improved quality
Biotic and abiotic resistance
Change in maturity duration
Wider adaptability
Desired agronomic characteristics
Nutrient management
There are 16 nutrient which are essential for plants
Carbon, hydrogen and oxygen are called the framework elements
The nutrients required in relatively large quantity for growth and development of
plants are called macro nutrients. These are nitrogen, phosphorous, potassium,
calcium, magnesium, and sulphur
The nutrients required in low quantity are called micro nutrients. These are iron,
manganese, boron, zinc, copper, molybdenum, and chlorine.
Manure
o Manure is prepared by the decomposition of animal excreta and plant waste.
o Manure is known to have a large quantity of organic materials and little amount of
plant nutrients.
o Manure helps in enriching the soil with organic matter and nutrients.
o Cow dung, animal refuse, domestic wastes, etc., is decomposed to form manure.
Fertilizers
o Fertilisers are commercially-available plant nutrients.
o They can be organic or inorganic in nature. They ensure the healthy growth and
development of plants by providing nitrogen, phosphorus, potassium, etc.
o Urea, Potash, Ammonium nitrate etc are some examples of fertilisers.
Composting
o Composting is a process in which farm waste materials such as livestock excreta
(e.g., cow dung), vegetable wastes, domestic wastes, and sewage wastes are
decomposed in pits to release the organic matter and nutrients.
o When composting is done using earthworms to hasten the process of
decomposition, it is called vermicomposting.
Crop protection
Use of pesticides is the most common method of eradicating weeds, pests, and
infectious diseases.
Pesticides are commercially available as herbicides, fungicides, insecticides, etc.
Excessive use of these chemicals can cause health hazards and environmental
problems.
Animal husbandry
Animal husbandry deals with the scientific management of livestock. These include
cattle farming, poultry farming, fish culture, and bee culture.
Cattle farming is done to obtain milk and draught labour for agricultural purposes.
Poultry farming is undertaken to obtain egg production and meat.
Fish is a cheap source of animal protein for our food. Therefore, fish culture is an
important part of animal husbandry.
In composite fish culture both local and imported fish species are used to increase the
fish yield.
Aquaculture involves the production of aquatic animals that are of high economic
value such as prawns, fishes, lobsters, crabs, shrimps, mussels, oysters, etc.
The practice of bee keeping is known as apiculture. Bee farms are also known as
apiaries.
Local varieties of bees used commonly for honey production are Apis cerana, Apis
dorsata, A. florae.
An Italian bee variety A. mellifera is used for commercial production of honey