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