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❖ In a chemical reaction, at least one of the following will occur:
Change in state
Change in colour
Evolution of a gas
Change in temperature

❖ Chemical equation: A symbolic representation of the reactants, products and their physical states.

❖ Balanced chemical equation: Here, the total number of atoms on the reactant side is equal to the total number of atoms on the product side.

❖ How to balance an equation
Step - I: Write reactants and products
Step – II: Balance the max. number of a particular atom on both sides
Step – III: Balance other atoms

Exothermic reactions: In these types of reactions, heat is released.

Endothermic reactions: In these types of reactions, heat is absorbed.

Types of reactions
Combination reaction: Here, two or more reactants combine to form one single product.
Example:
Decomposition reaction: Here, a single reactant breaks into several simple products.
Example:
Displacement reaction: Here, one element replaces another element from a compound and forms a new compound.
Example:
Double displacement reaction: The elements form two compounds which interchange their position.
Example:
Oxidation and reduction reactions
Oxidation: In this type of reaction, a substance gains oxygen or releases hydrogen.
Example:
Reduction: In this type of reaction, a substance gains hydrogen or releases oxygen.
Example:
Redox reactions: Reactions where simultaneous oxidation and reduction reactions take place are called redox reactions. Example:

❖ Corrosion – The process of coating up of a metal by a layer of some other substance due to the presence of some external substances (such as acids and moisture) is called corrosion.

Rancidity – The process of oxidation of fats and oils leading to the change of their taste and smell is called rancidity.Chapter 2: Acids, Bases and Salts

❖ Acids: These are the substances having sour taste. They turn the colour of blue litmus to red.

Base: These are the substances having bitter taste. They turn the colour of red litmus to blue.

Indicator: It is a dye that gives different colours in acids and/ or bases. Turmeric is a natural indicator.

Reaction with metals:
Acid + Metals → Salt + Hydrogen gas
Zn + H2SO4 → ZnSO4 + H2
Base + Metals → Salt + Hydrogen gas
Zn + 2NaOH → Na2ZnO2 + H2

Reaction of acids with metal carbonates and metal hydrogen carbonates
Metal carbonate/Metal hydrogen carbonate + Acid → Salt + Water + CO2
Na2CO3 + 2HCl → 2NaCl + H2O + CO2

Metal oxide + Acid
Metal oxide + Acid → Salt + Water

Non-metal oxide + Base
Non-metal oxide + Base → Salt + Water

Acid–Base reaction
Acid + Base → Salt + Water
NaOH + HCl → NaCl + H2O

In water solution:
Acid releases H+ ion
H+ + H2O → H3O+
HCl + H2O → H3O+ + Cl
Base releases OH ion
Higher H+ concentration → Strong acid
Lower H+ concentration → Weak acid
Higher OH concentration → Strong base

pH → The measure of acidity or alkalinity (Measured on a scale of 0 to 14)
pH 7 → Neutral solution
pH < 7 → Acidic solution
pH > 7 → Basic solution
Human body pH = 7.0 – 7.8
Change in pH in body causes → Tooth decay, stomach pain, burning pain (Honey bee)

Common salt (NaCl) : Has pH = 7

❖ Bleaching powder CaOCl2 (calcium oxychloride)
Preparation:
Ca(OH)2 + Cl2 → CaOCl2 + H2O

Use:

Oxidising agent
Disinfecting material

Baking soda → NaHCO3 (Sodium hydrogen carbonate)
Preparation:
NaCl + H2O + CO2 + NH3 → NH4Cl + NaHCO3
Use:
Making baking powder
Ingredient for antacids
Soda–acid fire extinguisher

Washing soda → Na2CO3.10H2O
Preparation:
Na2CO3 + 10H2O → Na2CO3.H2O
Use:
In glass, soap, paper industries
Making sodium compounds such as borax
As domestic cleaning agent
Removing permanent hardness of water

Plaster of Paris
Preparation:

Use:
For making toys
For making decorations
For setting fractured bones
Chapter 3: Metals and Non-metals

❖ Metals
Physical properties
Shining surface (in pure state) [called metallic lustre]
Generally hard [varies from metal to metal]
Malleability [ability to make thin sheets by beating]
Ductility [ability to make wire by drawing] [Gold is the most ductile element]
Good conductor of heat
High melting point
Conduct electricity
Sonorous [Produce sound]
Chemical properties
Combine with oxygen to form oxides: Example: 2Cu + O2 → 2CuO
Soluble metal oxides are called alkali. Na and K react very easily with O2. So, they are kept immersed in kerosene.
Reaction with water:
Metal + Water → Metal oxide + H2
If oxide is soluble, then metal hydroxide is formed.
2K + H2O → 2KOH + H2 + Heat
Reaction with Acids
Metal + Dilute acid → Salt + H2
Reactivity: Mg > Al > Zn > Fe > Cu
Aqua regia: Freshly-prepared concentrated HCl+ and concentrated HNO3 in 3:1 ratio
It can dissolve gold and platinum.
Reaction with solutions of other metal salts: Displacement reactions
Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Cu > An > Ag

Non-metals
Physical properties
Do not have lustre
Generally, exist in liquid and gaseous states
Are neither malleable nor ductile
Bad conductors of heat and electricity
Are non-sonorous

Metals + Non-metals

Physical properties of Ionic compounds
They are usually found in solid state
Hard [because of strong attraction force]
Are usually brittle in nature
High melting and boiling points
Soluble in H2O; insoluble in kerosene, petrol
Conduct electricity in H2O solution
❖ Extraction of metals

Less active metals

Moderately active metals
Roasting – Heating of sulphide ore in excess air
2ZnS + 3O2 → 2ZnO + 2SO2
Calcination – Heating of carbonate ores in limited air
ZnCO3 → ZnO + CO2
Chapter 4: Life Processes

❖ Life processes: Continuously perform the functions of maintenance in living organisms.
Examples: digestion, respiration, circulation etc.

❖ Nutrition: Process of obtaining nutrients from the environment. Two types- autotrophic and heterotrophic
Autotrophic nutrition
Synthesis of food by photosynthesis
Photosynthesis equation:
Two phases of photosynthesis- light and dark reactions
Light reaction: light energy absorbed, H2O split into H2 and O2, ATP and NADPH2 synthesized
Dark reaction: CO2 reduced to carbohydrates
Heterotrophic nutrition
Generally derive energy from plants and animal sources
Mainly of three types: holozoic, parasitic, and saprophytic
Digestion: mechanical and chemical reduction of ingested nutrients
Human digestive system: consists of the long alimentary canal
Parts of alimentary canal

Accessory organs: pancreas, liver

❖ Respiration
Enzymatically-controlled energy released from the breakdown of organic substances
Two types- aerobic and anaerobic
Aerobic respiration
Oxidation of food materials with the help of oxygen
Yields 36 ATP
First step- glycolysis (occurs in the cytoplasm), 2 pyruvate molecules produced
Second step- acetyl CoA produced
Third step- Kreb’s cycle inside the mitochondrial matrix, energy produced
Last step- energy converted to ATP by ATP synthase enzyme
Anaerobic respiration
Oxidation of nutrients without utilizing molecular oxygen
Yields 2 ATP
First step- glycolysis (occurs in the cytoplasm), 2 pyruvate produced
Second step- break down of pyruvic acid into waste products
Human respiration

Bronchioles divide to form many alveoli
Alveoli are sites of gas exchange
O2 present in alveolar blood vessels transported to body cells

Transportation
A liquid medium is required
Transportation in humans
Blood, lymph- involved in transportation
Components of blood- RBCs, WBCs, platelets, and plasma
Two types of blood vessels- arteries and veins
Arteries carry oxygenated blood, except pulmonary artery
Veins carry deoxygenated blood, except pulmonary vein
Human heart divided into four chambers – right auricle, right ventricle, left auricle, and left ventricle

Right side of the heart receives deoxygenated blood
Left side of the heart receives oxygenated blood
Transportation in plants
Transport of water-xylem
Transport of food- phloem

Excretion: Involves removal of harmful metabolic wastes from the body.
Excretion in humans

Nitrogenous wastes such as urea and uric acid are removed
Nephron- basic filtration unit
Main components of the nephron are: glomerulus, Bowman’s capsule, renal tube

Chapter 5: Control and Coordination

Control and coordination: Working together of various integrated body systems in response to changes in the body for maintenance of bodily functions.
Nervous and muscular tissues provide control and coordination
• Neurons -functional units of the nervous system, conduct messages in the form of impulses
• Synapse- a small gap between the axon of one neuron and the dendrite of the next neuron
Three types of responses of the nervous system
Reflex action
⚬ Automated action in response to a stimulus
Possible due to quick detection by sensory receptors and the resultant movement of muscles
Reflex arc situated in the spinal cord
Voluntary action: Actions such as writing, talking etc. that are under the control of the body.
Involuntary action: Actions such as breathing, digestion etc. that are not under conscious control

Parts of the nervous system
Human nervous system divided into- central nervous system (CNS) and peripheral nervous system (PNS)
CNS consists of the brain and spinal cord
PNS consists of the nerves that connects the CNS to different parts of the body
The Brain, spinal cord, and nerves are the important parts of the nervous system
Brain

Human brain is classified into- forebrain, midbrain, and hindbrain
Forebrain- cerebrum, thalamus, and hypothalamus
Midbrain
Hindbrain- pons, medulla, and cerebellum

Tropic movement
Directional movement of a specific part of the plant in response to an external stimulus
Phototropism- response to light
Geotropism- response to gravity
Hydrotropism- response to water
Chemotropism- response to chemicals
Thigmotropism- response to touch

Chemical coordination in plants
Growth and development in plants is possible because of growth hormones or phytohormones
Auxin, Gibberellin, cytokinin, abscisic acid and ethylene are examples of phytohormones

Chemical coordination in animals
Carried out with the help of hormones
Hormones are secreted by endocrine glands such as the pituitary gland, thyroid gland, adrenal gland, pancreas etc.
Chapter 8:  Sources of Energy

Qualities of a good fuel/source of energy are:
• That would do a large amount of work per unit volume or mass
• Easily accessible
• Easy to store and transport
• Economical

Factors to be considered for choosing fuel are:
• How much heat it produces
• Less smoke generation
• Easy availability

Conventional sources of energy:
Fossil fuelsCoal, petroleum and natural gas
Easy availability
Generate heat that is easily converted into electricity
Non-renewable
Limited reserve
⚬ Cause air pollution

Non-conventional sources of energy
Solar energy – Solar cooker, solar water heater (very efficient for small scale electricity production)
Tidal energy, wave energy, ocean thermal energy
Geothermal energy – Heat energy inside the earth
Wind energy
Nuclear energy – Not dependent on solar energy, never-ending source, very efficient source, more environment friendly

Thermal power plant – Coal and petroleum are burned to produce heat

Hydro power plant – (Renewable source)
• ProblemsLimited places for construction (only Hilly areas)

Technological improvement
Bio-massCharcoal, cow-dung, vegetable waste, sewage
• Wind energyEnvironment friendly, renewable
Chapter 7:  Magnetic Effects of Current

Properties of magnetic field lines
• Originate from the North pole and end at the South pole [outside the magnet]
• They are closed continuous lines
• Density of the lines increases near the poles and decreases away from the poles
• Lines never cross each other

Magnetic field lines of current carrying wire
It is circular with axis as the wire.
• Varies with distance from wire. (Inversely proportional)
• Direction depends on direction of current.
• Deflection of compass near a conductor (Shown by arrow):

Right-hand thumb rule:
When thumb is in direction of current, the curl of fingers gives direction of circular magnetic field.

Corkscrew rule
If one drives a corkscrew in the direction of the current, then the direction in which the handle is turned is the direction of the magnetic field on the magnetic field lines.

Solenoid
Solenoid is a cylindrical coil having many turns of insulated wires wrapped closely. When current is passed through the coil, a magnetic field is produced along the axis of the coil.

Direction of force on a current carrying conductor in a magnetic field can be given by Fleming’s left-hand rule.

Application of magnetic force – Electric motor
When current is passed through a coil kept in a magnetic field, a force acts on it which rotates the electric motor.

Electromagnetic Induction
Generation of a current in the conductor due to a varying magnetic field (moving magnet, or moving conductor)
Application – AC/DC generator

Direction of induced current in a conductor moving in a magnetic fierld can be given by Fleming’s right hand rule.
Chapter 6:  Electricity

Electric current: Amount of charge flowing per unit time.

Unit: IAmpere
Q Coulomb (C)
t = Second (s)

Potential difference:
The potential difference between two separate points is defined as the work done to move a unit positive charge from one point to another.
$V=\frac{W}{Q}$

Unit:
Ohm’s law:
Under constant physical conditions (i.e., constant temperature, pressure etc.), the current flowing through a conductor is directly proportional to the potential difference across the conductor.
Current  potential difference (V I)
V = IR     Where, R = resistance
Unit of resistance (R) $\Omega$ (Ohm)
$1\mathrm{\Omega }=\frac{1\mathrm{V}}{1\mathrm{A}}$
Factors on which resistance depends
R l, when area of cross-section and material are constant l = length
R A, when l and material are constant  A = perpendicular cross-section
Overall, $R\propto \frac{1}{A}$
Or, , where $\rho$ is resistivity which is different for different material
Resistivity of a substance is equal to the resistance of a unit square of that substance.
Unit ($\rho$) $\Omega$. m

Net resistance of resistors in series connection
Rnet = R1 + R2 + R3 + … + Rn

Net resistance of resistors in parallel
$\frac{1}{{R}_{net}}=\frac{1}{{R}_{1}}+\frac{1}{{R}_{2}}+...+{R}_{n}$

Heating Effect of current, heat produced depends on:
Potential difference (V)
Electric current (I)
Time for which current passes (t)
Electric energy = VIt
It can be written as: E = I2Rt $\frac{{V}^{2}}{R}t$
Unit – 1 kWh = 3.6 × 106 J

Application: Electric iron, toaster, fused wire
Fuse wire: a low-melting point wire connected in series with electric devices for safety.

Electric power: $P=VI={I}^{2}R=\frac{{V}^{2}}{R}$
Unit: 1 W = 1V × 1A
Chapter 1: Carbon and Its Compounds

Covalent bonds: The bonds formed by the sharing of electrons are known as covalent bonds.

Carbon contains four electrons in its valence shell. It always forms covalent bonds as it is difficult for it to lose or gain four electrons in order to complete its octet.

Allotropy: The property of an element to exist in different forms. Example: Diamond, graphite and buckminsterfullerene are the three allotropes of carbon.

Catenation: The ability of an element to combine with itself through covalent bonds. Carbon can combine with itself to form chain, branched, and ring structures.

Hydrocarbons: These are compounds of carbon and hydrogen.

Saturated compounds: The compounds of carbon that contain only single bonds among carbon atoms. Example: alkanes

Unsaturated compounds: The compounds of carbon having double and/ or triple bonds. Example: alkenes, alkynes
Homologous series: A series of carbon compounds having different numbers of carbon atoms, but containing the same functional group. Some functional groups in carbon compounds are shown in the given table.

 Hetero atom Name of functional group Formula of functional group Chlorine/Bromine Halo- (Chloro/Bromo) –Cl, –Br Oxygen Alcohol –OH Aldehyde –CHO Ketone >C=O Carboxylic acid –COOH

The nomenclature of organic compounds is done by using a set of rules. Names of some common compounds are shown in the given table.
 Functional group Prefix/Suffix Example 1. Halogen Prefix: chloro, bromo, etc. 2. Alcohol Suffix: -ol 3. Aldehyde Suffix: -al 4. Ketone Suffix: -one 5. Carboxylic acid Suffix: -oic acid 6. Double bond (alkenes) Suffix: -ene 7. Triple bond (alkynes) Suffix: -yne

Chemical properties of carbon compounds
Combustion reaction:
Carbon burns in air to form carbon dioxide and hydrocarbons burn in air to give carbon dioxide and water. Heat and light are also released in these processes.
CH4 + O2 → CO2 + H2O + Heat and light
Oxidation reaction:
Combustion of carbon to form carbon dioxide is an oxidation reaction. When alcohols are oxidised, carboxylic acids are obtained.

Unsaturated hydrocarbons yield saturated hydrocarbons when reacted with hydrogen in the presence of catalysts.

Substitution reaction:
Under specific conditions, hydrogen atoms present in hydrocarbons can be replaced by atoms of other elements like chlorine and bromine.

Ethanol (CH3CH2OH)
Physical properties
Liquid at room temperature
Is a good solvent
Soluble in water in all proportions
Chemical properties
Reacts with sodium metal to release hydrogen gas

Reacts with conc. H2SO4 to form ethene

Ethanoic acid (CH3COOH)
Physical properties
Has a melting point of 290 K
5-8% solution of acetic acid is known as vinegar
Is a weak acid
Chemical properties
Esterification reaction

The reaction reverses itself in the presence of a base and is called saponificaiton reaction.

The two ends of molecules of soaps and detergents are different. Their one end is hydrophilic and the other is hydrophobic. Presence of these two types of ends is responsible for the cleansing action of soaps.Chapter 2: Periodic Classification of Elements

❖ The earliest classification was based on grouping the known elements as metals and non-metals.

Law of Triads: Given by Dobereiner. He was the first person to illustrate the relationship between the atomic masses of elements and their properties. A set of elements showing triads is as under:

Law of Octaves: Given by Newlands. He arranged the known elements in the increasing order of their atomic masses. The law is applicable only to the elements having low atomic masses.

Mendeleev’s periodic law: Mendeleev gave a periodic law which states that the properties of elements are a periodic function of their atomic masses.
Achievements of Mendeleev’s periodic table:
⚬ Mendeleev left some gaps in his periodic table so that the undiscovered elements could get a place in it without disturbing the positions of the other elements.
⚬ Noble metals were not discovered at that time. When they were discovered later, they got a place in Mendeleev’s table without disturbing the positions of the other elements.
Limitations of Mendeleev’s periodic table:
⚬ It failed to explain the position of hydrogen.
⚬ It was not able to explain the position of isotopes.
⚬ In the table some elements having higher mass were kept before the elements having lesser atomic mass.

Modern periodic law:  It states that the properties of elements are a periodic function of their atomic numbers, not their atomic masses.
The modern periodic table consists of 7 periods and 18 groups.
Elements having the same valence shell are present in the same period. Elements having the same number of valence electrons are present in the same group.
The Metals are present on the right-hand side of the periodic table, whereas non-metals are present on the left-hand side of the periodic table.
The atomic size as well as metallic character of elements increases on moving down the group and decreases on moving from left to right in a period.
Chapter 4: Heredity and Evolution

Heredity: Transmission of characteristics or traits from parents to offsprings

Variations: Difference among individuals of a species and also, among offsprings of same parents. Variations are of two types- heritable and non-heritable

Basis of heredity: each trait is influenced by both maternal and paternal DNA

Mendel’s work
• Proposed that heredity controlled by genes
• Performed experiments on garden peas (Pisum sativum)
• Used seven contrasting pairs of characters or traits
Dominant trait: able to express itself over another contrasting trait
Recessive trait: unable to express its effect in the presence of a dominant trait
• Mendel represented- dominant trait as upper case (e.g.,T for tallness) and recessive trait as lower case (e.g., t for shortness)
Homozygous: when the factors or genes of a trait are similar e.g.,TT or tt
Heterozygous: when the factors or genes of a trait are different e.g., Tt
Genotype: genetic constitution of an organism e.g., pure tall- TT
Phenotype: observable traits or characteristics of an organism e.g., tallness, shortness etc.
Genotypic ratio: expected ratio of genotypes produced by a particular cross
Phenotypic ratio: expected ratio of phenotypes produced by a particular cross
Monohybrid cross: involves only one pair of contrasting characters
Dihybrid cross: involves two pairs of contrasting characters
Stages of Mendel’s experiment
Selection of parents- true breeding with contrasting pairs of traits e.g., pure tall (TT) and pure dwarf (tt) pea plants were selected
Obtaining F1 plants- F1 generation is the first filial generation, formed after crossing desirable parents e.g., crossing pure tall (TT) and dwarf (tt) plants gives heterozygous tall (Tt) F1 plants
Self-pollination of F1 plants- involves crossing F1 plants to obtain F2 plants
Conclusions of Mendel’s experiment
Each characteristic in an organism is represented by two factors
Two factors are- dominant and recessive
Two contrasting factors when present in an individual do not blend
When more than two factors are involved, they are independently inherited

Heredity at cellular level
• DNA associates with proteins to form chromosomes
• Every somatic (body) cell of the human body has 23 pairs (46) of chromosomes
Autosomes- first 22 pairs of chromosomes that do not determine the sex of an individual
Sex chromosomes- last pair of chromosomes, represented as X and Y
• Females have two X chromosomes, XX
• Males have one X and one Y chromosome, XY

Sex determination in humans
• Gametes receive half of the chromosomes
•  Male gametes have 22 autosomes and either X or Y sex chromosome
•  Male gametes can be of two types, 22 + X or 22 + Y
• Female gametes can be of only one type, 22 + X
• Sex of a baby is determined by the type of the male gamete (X or Y) that fuses with the female gamete

Evolution
• Changes in inherited traits from one generation to the next in a species
Speciation- formation of new species
Causes of evolution
Natural selection: a process that results in an increased survival and reproductive success of individuals that are well adjusted to the environment
Genetic drift: accidental change in the frequency of genes in a small population
Acquired traits: a trait that an individual experiences during his lifetime a) involves changes in non-reproductive tissues b) cannot be passed on to the progeny
Inherited traits: distinguishing qualities or characteristics that one acquires from ancestors (i) involves changes in DNA (ii) transmitted to progeny

Evolutionary relationships
Homologous organs: similar in origin, but perform different functions e.g., forelimbs of humans and wings of birds
Analogous organs: different origins, but perform similar functions e.g., wings of birds and bats
Fossils: remains of organisms that once existed on the Earth
Palaeontology: science dealing with the study of fossils
Vestigial organs: organs present in the reduced form, having no function
• Human beings (Homo sapiens): evolved from primates in Africa
Chapter 6:  Human Eye and the Colorful World

Important components of the human eye
Image forms on the retina
Iris controls the size of the pupil
Pupil controls the amount of light
Lens can adjust its focal length. It is called power of accommodation.
Thickness of the eye can be controlled by ciliary muscles.

Nearest focal distance of lens = 25 cm

Common defects in eye
Myopia/near-sightedness
Problem: Distant objects cannot be seen clearly
Image is formed in front of the retina
Correction concave lens
Hypermetropia/far-sightedness
Problem: Near objects are not seen clearly
Image formed beyond the retina
Correction – convex lens
Presbyopia
Problem:  Near-focus distance increases with age
Power of accommodation decreases
Correction– bi-focal lens

Prism

Dispersion

Atmospheric refraction
Twinkling of stars – caused by changing air density in the atmosphere
Early sunrise and delayed sunset – caused by refraction of light through the atmosphere

Scattering: Tyndall effect
Atmospheric particles, smoke, tiny water droplets, suspended particles of dust, and air molecules scatter sunlight. Therefore, the path of light becomes visible.
Sky is blue- because light near blue wavelength scatters most
Danger signs are red in colour-  because red light scatters least
Chapter 3: How Do Organisms Reproduce

❖ Reproduction
• Biological process by which a living organism produces an offspring similar to itself
• Information transferred from the parents to the offspring in the form of DNA
• DNA (Deoxyribonucleic acid)- a genetic material found in chromosomes present in the nucleus of a cell
• Two types of reproduction—sexual and asexual

❖ Asexual reproduction
• Does not involve the fusion of gametes
• Requires only one parent
• Offspring’s produced are exact copies of their parents

Modes of asexual reproduction
⚬ Fission- involves cell division or splitting of cells
⚬ Is of two types:
Binary fission
 Along any plane e.g., Amoeba Along single longitudinal plane e.g., Leishmania

Multiple fission: e.g., Plasmodium
Fragmentation- New organisms are formed from fragments of parents. e.g., lichens
Regeneration- New organisms are formed from body parts. e.g., Planaria
Budding- New individuals form protrusion called buds. e.g., Hydra
Vegetative propagation- New plants are formed from the vegetative parts .e.g., Bryophyllum
Spore formation- Large number of spores produced in sporangia. e.g., Rhizopus

❖ Sexual reproduction
• Involves fusion of male and female gametes
• Requires two parents
• Allows more variations in offsprings
Sexual reproduction in plants
Angiosperms- flowering plants
Parts of flowers– sepals, petals, stamens, and carpels/pistils
Stamens: Male reproductive parts of flowers and consists of anther and filament
Carpels: Female reproductive parts of flowers and consists of style, stigma, and ovary
Bisexual flowers: Both stamens and carpels are present e.g., hibiscus
Unisexual flowers: Either stamen or carpel is present e.g., corn
⚬ Pollen released from the bursting of anther, which contains male gametes
⚬ Each ovule contains one egg cell or female gamete
Pollination: transfer of pollen from the anther of one flower to the stigma of the same or different flower
Fertilization: Process of fusion of male and female gametes
⚬ After fertilization: zygote = embryo, ovule = seed, ovary = fruit

Sexual reproduction in animals
Puberty: A period of physical change by which a child’s body becomes an adult’s body and capable of reproduction
Secondary sex characteristics: The body changes during puberty
Male reproductive organs: Pair of testes, vas deferens, prostate gland, seminal vesicles
Testes: Produce sperms and hormone testosterone
Sperms: Contain male gametes
Female reproductive organs: Pair of ovaries, pair of oviducts, uterus, and vagina
⚬ Ovaries contain thousands of eggs
⚬ Sperms enter the female body through the vagina
Fertilization: The process of fusion of the nucleus of the sperm with the ovum to form a zygote
⚬ Zygote divides to form an embryo
⚬ Embryo implanted in the uterus
⚬ Foetus develops inside the mother’s body for nine months
Menstruation: If the egg is not fertilized, then the uterus lining breaks down and is released in the form of blood and mucous through the vagina
Sexually transmitted diseases: Infections that get transferred through sexual contact e.g., herpes, HIV-AIDS, syphilis, gonorrhea etc.
Contraceptive methods help avoid pregnancy: These include natural methods, barrier methods, oral contraceptives, implants, and surgical methods
Chapter 7: Our Environment

Environment: natural surroundings and external conditions of an organism, which include all living and non-living factors that affect the organism

Organism: is the basic unit of an ecological hierarchy, can be unicellular such as Amoeba and Paramecium or multicellular such as humans

Population: a group of individuals of the same species inhabiting a given geographical area at a particular time and functioning as a unit

Community: includes all individuals of different species living within a certain geographical area

Ecosystem: includes both living and non-living components of an area
Components of an ecosystem
Abiotic factors: light, temperature, water, air etc.
Biotic factors: living organisms
Autotrophs: organisms that can manufacture their own food from inorganic raw materials, also known as producers
Heterotrophs: cannot synthesize their own food, are dependent on other organisms
Herbivores: feed only on plants e.g., deer, horse, sheep etc.
Carnivores: eat other animals e.g., frog, cat, spider etc.
Omnivores: feed on both plants and animals e.g. bear, monkey, man etc.
Decomposers: obtain nutrients by breaking down remains of dead plants and animals, includes some bacteria and fungi
Functions of an ecosystem
Productivity: rate of production of organic matter (food) by producers
Decomposition: breakdown of organic matter or biomass with the help of decomposers

Energy flow through an ecosystem
Trophic level: level of species in an ecosystem on the basis of the source of nutrition
Producers: form the first trophic level, they manufacture food
trophic levels are connected through food chains
Food chain: a linear sequence of organisms in which each organism is eaten by the next member in the sequence e.g., plants®grasshopper®frog®snake®eagle
Food web: interconnected network of food chains
10% law of energy transfer: only 10% energy is transferred from a lower trophic level to a higher trophic level, which means that energy keeps on decreasing as one moves up different trophic levels
Biomagnification: increase in the concentration of pollutants or harmful chemicals with each step up in the food chain
Human influence on the environment
Global warming: increase in the average temperature of the Earth’s surface
Greenhouse gases: CO2, CH4, O3, CFCs etc.
Ozone layer: present in the stratosphere, absorbs ultraviolet radiations. It gets depleted due to an  increased concentration of chlorine in the atmosphere -
Cl + O3 → ClO + O2
Biodegradable wastes: produced mainly from plant and animal sources that can be broken down by living organisms
Non-biodegradable wastes: includes wastes such as plastic, metals etc., that cannot be broken down by living organisms
Chapter 8: Management of Natural Resources

Natural resources
These are the natural substances provided by nature that are considered economically important. Example: soil, air, water etc.

3R principle to save environment
Reduce
It refers to the reduction in the consumption of resources.
Example - Repairing taps to check water leakages
Recycle
It means to synthesise or extract useful materials from wastes.
Example - Plastic, paper, glass, and metals can be extracted from the waste scrap
Reuse
It means using a product again and again.
Example - Plastic bottles containing jams can be used to store pulses in the kitchen

Need to manage resources
Resources are in limited supply
Human population is increasing, so the demand for these resources is also increasing exponentially
Management of resources should be done with a long-term perspective, so that they can be exploited by the future generations
The damage caused to the environment while extracting resources should be reduced

Type of Natural Resources
• Forests are biodiversity hotspots as they are homes to large number of plants, animals, and microbes.

Stakeholders in forest resources
• The tribal people living inside and around forests depend on forest resources
Traditional people played important role in the past in protecting forests.
Example - Amrita Devi Bishnoi sacrificed her life along with 363 other people in 1731 to protect ‘Khjiri’ trees from being cut down in Khejrali village near Jodhpur.
Products of forests
Fire wood
Lumber
Lac
Herbs
Honey
Fruits
The forest department of the government
Owns the land and controls forest resources
Forest department ignores local knowledge and traditional management practices of the forest
Vast tracts of the forest is converted into plantations of teak, pine and eucalyptus, which supports little biodiversity.
The industrialists
Use forest resources in unsustainable manner
Power lobby which pushes the government, ignoring the local people, for the use of forest resources
The wildlife enthusiasts
Not dependent on forests
Considerable say in forest conservation

Water resources
• Basic need of life
• Most of the Indian agriculture is dependent on monsoons
Bandharas and tals in Maharashtra
Ahars and Pynes in Bihar
Ponds in Jammu
Surangamo in Kerala
Kattas in Karnataka

Coal and petroleum
They are non-renewable sources of energy.
Burning of coal and petroleum releases toxic gases such as carbon monoxide, sulphur dioxide, nitrogen dioxide, and greenhouse gases such as carbon dioxide and methane.
Use of coal and petroleum can be reduced by using alternate sources of energy and switching over to cleaner biofuels.

Sustainable Management
• Interests of all the stakeholders should be given a proper say.
• Benefits of development should reach each and every individual and all generations.
Chapter 5: Light, reflection and refraction

❖ Reflection of light is the change in the path of a light ray upon collision with an interface of two medium.

❖ Laws of reflection:
• i (Angle of incidence) = r (angle of reflection)
Rays AO, OM and OB lie in the same plane.

❖ Terms related to spherical mirrors
Centre of curvature is the centre of the sphere of which the spherical mirror is a part

Pole is the centre of mirror

Focus is a point where parallel rays (parallel to the principal axis) meet or appear to meet after reflection

Concave mirror and nature of image formed
All images are real and inverted, except when the object is between the focus and the pole.
Image size = object size when the object is at the centre of curvature

Uses:
 ⚬ Torch reflector ⚬ Search light ⚬ Vehicle headlight ⚬ Dentist’s mirror ⚬ Shaving mirror

Convex mirror and nature of image formed
Virtual image
Erect image
All images are diminished
Uses:
⚬ Rear-view mirror
⚬ Security mirror

Mirror formula:
For concave, f  –ve, for convex, f  +ve
Magnification

❖ Laws of refraction
•  AO (incident ray), OB (refracted ray), and MON (normal to the interface) are co-planar.
•  = constant      (Snell’s law)

❖ Refractive index (R.I.)
${}_{1}{}^{2}\mu$(m of 2 w.r.t. 1)
Absolute RI when medium I = Vacuum or air
Speed of light{vacuum} = 3 × 108 m/s
 Medium (Optically denser) = m > 1 → Optically rarer = m < 1 → In all medium

❖ Terms related to spherical mirrors
Centre of curvature = Centre of the sphere of which the lens surfaces is a part of (Same as Spherical mirror)
Focus = Where parallel rays meet after refraction (On principal axis = principal focus)

Convex lens and nature of image formed
Virtual and erect images – when the object is placed between focus and the optical centre (Magnifying glass)
Real and inverted image at all po
Image size = object size when object is at centre of curvature

Concave lens and nature of image formed
Virtual and erect at all object positions

❖ Lens Formula:
For concave lens f = –ve, convex lens f = +ve

Magnification,

Lens power P (Unit dipotre)
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