Science Notes PDF

Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Chemistry Chemistry is the branch of science in which we study the properties, composition and structure of materials. It deals with the properties that distinguish one substance from another. Matter : Anything that occupies space and possesses weight is called matter. It is found in three states, i.e., solids, liquids and gasses. Now-a-days two more states of matter are considered i.e., Plasma (Ionised gases containing super energetic and super excited particles and Bose-Einstein condensates or BEC (a gas at super low temperatures with extremely low density). Kinetic theory of Matter : All matter consists of extremely small particles which are capable of independent existence. These particles possesses kinetic energy and attract other molecules. In solids inter-molecular force of attraction is greatest and kinetic energy is the least. In liquids inter-molecular force of attraction is lesser and kinetic energy is greater. In gasses inter-molecular force of attraction is the lest and kinetic energy is the greatest. Boiling Point : The temperature at which liquid converts in to vapours is called its boiling point. Boiling point of water is 100°C. The boiling point increases in the presence of impurities. That's why boiling point of sea water is more than the boiling point of pure water (as the former contains impurity). It usually decreases at high altitudes, that's why at high altitudes, the boiling point of water is less than 100°C and more time is required to cook a food. Melting Point : It is a temperature at which a substance converts from its solid state to liquid state. Meling point of ice is 0°C; It decrease in the presence of impurity Latent Heat of Fusion is the amount of heat absorbed as a substance changes phase from liquid to solid, a process called fusion or solidification. Latent Heat of Vaporization is the amount of heat absorbed when a substance changes phase from liquid to gas. Sublimation is a specialized change of state when a solid substance skips the liquid phase and moves directly into the gas phase. This occurs because the substance absorbs energy so quickly from the surroundings that melting never occurs. For example, Dry Ice - Solid carbon dioxide is known as "dry ice" and sublimates at room temperature. Element is the simplest form of matter which cannot be broken into simpler substances by any physical or chemical method. For example, copper, silver, hydrogen, etc. A compound is a substance which contain two or more elements combined in fixed proportion of weight. It can be decomposed into simpler substances or elements. For example, water is compound of hydrogen and oxygen. A chemical formula tells us the number of atoms of each element in a compound. It contains the symbols of the atoms of the elements present in the compound. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Common Names and Formulas of Important Chemical Compounds 1. Common Names: Baking Powder, Chemical Compounds: Sodium Bicarbonate Chemical Formula: NaHCO3 2. Common Names: Blue Vitriol, Chemical Compounds: Copper Sulphate Chemical Formula: CuSO4.5H2O 3. Common Names: Bleaching Powder, Chemical Compounds: Calcium Oxychloride Chemical Formula: CaOCL2 4. Common Names: Chloroform, Chemical Compounds: Trichloro Methane Chemical Formula: CHCl3 5. Common Names: Chalk (Marble), Chemical Compounds: Calcium Carbonate Chemical Formula: CaCo3 6. Common Names: Caustic Potash, Chemical Compounds: Potassium Hydroxide Chemical Formula: KOH 7. Common Names: Caustic Soda, Chemical Compounds: Sodium Hydroxide Chemical Formula: NaOH 8. Common Names: Dry Ice, Chemical Compounds: Solid Carbondioxide Chemical Formula: CO2 9. Common Names: Gypsum, Chemical Compounds: Calcium Sulphate Chemical Formula: CaSo4 10. Common Names: Green Vitriol, Chemical Compounds: Ferrous Sulphate Chemical Formula: FeSo4 11. Common Names: Heavy Water, Chemical Compounds: Deuterium Oxide Chemical Formula: D2O, 12. Common Names: Vinegar, Chemical Compounds: Acetic Acid Chemical Formula: CH3COOH 13. Common Names: Washing Soda, Chemical Compounds: Sodium Carbonate Chemical Formula: Na2CO3 14. Common Names: Slaked Lime, Chemical Compounds: Calcium Hydroxide Chemical Formula: Ca(OH)2 15. Common Names: Quick Lime, Chemical Compounds: Calcium Oxide Chemical Formula: CaO 16. Common Names: Plaster of Paris, Chemical Compounds: Calcium Sulphate Chemical Formula: CaSO42H2O 17. Common Names: White Vitriol, Chemical Compounds: Zinc Sulphate Chemical Formula: ZnSo4.7H2O 18. Common Names: Marsh Gas, Chemical Compounds: Methane Chemical Formula: CH4 Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) 19. Common Names: Magnesia, Chemical Compounds: Magnesium Oxide Chemical Formula: MgO 20. Common Names: Laughing Gas, Chemical Compounds: Nitrous Oxide Chemical Formula: N2O Mixture and its separation Method Mixture: A mixture is a substance that constitutes two or more element or compound, chemically combined together in any ratio. It can be separated into its constituent element by physical methods. It has variable melting and boiling point and the properties shown by the mixture are depend on its constituent element. Types of Mixture Heterogeneous Mixture: A mixture in which the constituent elements are distinctly visible, and do not show the properties of its constituent element. Normally the colloidal solution are heterogeneous in nature i.e. mixture of salt and sugar, suspensions etc. Homogeneous Mixture: A mixture in which the constituent element are uniformly distributed throughout the mixture and show the properties which are similar to the constituent element i.e. the electrolyte of sulphur in carbon dioxide. Process used for the separation of its constituent element Filtration: It is used for the separation of the insoluble solid component of the mixture from the soluble component in a given solvent, e.g. in car engines solid particles from engine oil are separated by air filters, for separation of naphthalene and urea. Crystallisation: This method is used to purify the solids, on the basis of heating. In which the pure component is left behind, e.g. for obtaining salt from the sea water. Evaporation: This is used to separate the volatile component from the non-volatile component. In this process the soluble solid solute dissolved in the solvent is obtained generally by heating the mixture, e.g. for manufacturing the ink. Centrifugation: This process is used for the separation of the insoluble particles from the liquid where normal filtration process does not work. This process normally depends on the particles size, density and viscosity. The principle is that the denser particles are forced to the bottom and the lighter particles stay at the top when rotate rapidly, e.g. separation of cream from the milk. Sublimation: It is used to separate sublimate volatile substances such as ammonium chloride from the non-sublimate substances such as sodium chloride. Sublimate substances are iodine, naphthalene, camphor. Distillation: Liquid having sufficient difference in their boiling point are separated through this process. Used for the preparation of distilled water from the normal ordinary water. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Fractional Distillation: It is used when there is a small difference in the boiling point of the liquids. This process is mainly used in industrial process, e.g. refining of the crude oil and manufacturing of the alcoholic beverages such as whisky and rum. Dalton’s Atomic Theory : Dalton defined atom as the smaller neutral particles of the matter which may have independent existence. Atom is the smallest particle of a matter that takes part in chemical reactions, but cannot exist in free state. Atom is made up of electrons, protons and neutrons. Protons and neutrons reside in the nucleus (at the centre of atom) whereas electrons revolve around the nucleus. Atoms combine to form molecules, the smallest part of matter which can exist in free state. Modern Atomic Theory : Atoms can be divided into : (a) Protons or positively charged particles having one unit of charge and one atomic weight. (b) Neutrons have no electrical charge and one atomic weight. (c) Electrons are negatively charges particles having no atomic weight. Isotopes : Atoms of the same element may possess different atomic weights. Such atoms of the same elements are called Isotopes. Thus isotopes have same atomic number but different atomic weight. Thus, Isotopes have the same number of protons (i.e., atomic number), but different number of neutrons and mass number (atomic number + number of neutrons), e.g., hydrogen has two isotopes, i.e., 1H1, 1H2. Element Carbon also has two isotopes. The normal ones are carbon-12. Those atoms have 6 neutrons. Carbon-14 actually has 8 neutrons. C-14 is considered an isotope of the element carbon. Isobars : Atoms of the different elements have same mass number but different atomic number. Such atoms are called isobars. Thus, Isobars have the same mass number but different atomic number. An example of a series of isobars would be 40S, 40Cl, 40Ar, 40K, and 40Ca. Isotones: Two nuclides are isotones if they have the same neutron number N, but different proton number Z. For example, boron-12 and carbon-13 nuclei both contain 7 neutrons, and so are isotones. Similarly, 36S, 37Cl, 38Ar, 39K, and 40Ca nuclei are all isotones of 20 because they all contain 20 neutrons. Structure of the atom : An element on the whole is electrically neutral, i.e., same number of electrons and protons. The entire mass of the atom is concentrated in very small part called nucleus. Electrons revolve around it in fixed orbits or shells having name K L M N O P etc. Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons. Electron was discovered by J. J. Thomson in 1897 when he was studying the properties of cathode ray. He won Nobel Prize in 1906 for discovering the elementary particle electron. Protons were discovered by Ernest Rutherford Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Neutrons were discovered by James Chadwick Nucleus was discovered by Ernest Rutherford. Nucleus is positively charged and is in solid state was discovered by Rutherford. Atomic number is the number of protons in an atoms. Mass number is the number of protons and number of neutrons. A periodic table for these elements was given by Mendelif in 1869. But the modern periodic table is given by Moosley. In this periodic table elements are arranged in order of their increasing atomic numbers. Electronic Theory of Valancy : Atoms combine to join molecules by rearrangement of their electrons in the outermost shell so as to attain a stable electronic configuration. The rearrangement results in the formation of chemical bonds between the atoms. Valancy of the atom is the number of electrons it tends to borrow or share. Valance electrons means the number of electrons in the outmost shell. Octet Rule : In chemical combination the atoms of elements tend to acquire 8 electrons (or 2 electrons in case of first shell) in their outermost shell. Chemical Bonding : The tendency of 2 atoms to form a bond between them depends on the net forces of attraction and repulsion. If the resultant effect of these forces leads to decrease in energy a stable chemical bond is formed. There are two kinds of bonds. (i) Ionic Bond or Electrovalent Bond is formed as a result of complete transfer of electrons from one atoms to another so that both atoms acquire the stable configuration. The atoms which loses its electron becomes a positively charged ion known as anion and the atom which gains its electron becomes negatively charged ion known as Cation. Such charged ions are held by electrostatic force of attraction forming an ionic bond. (ii) Covalent Bond : Atoms may also combine by sharing of electrons in the outermost shell to acquire a stable configuration. Metals and Non-Metals Elements can be classified as metals and non-metals. Metals are lustrous, malleable, ductile and are good conductors of heat and electricity. They are solids at room temperature, except mercury which is a liquid. Gold and silver are most malleable and best ductile metals. Silver is the best conductor of heat followed by copper. Aluminium and copper are good conductors of heat that’s why cooking utensils are made of them. Mercury offers high resistance to the flow of electric current. Sodium and potassium are so soft that they can be easily cut with knife. Almost all the metal oxide are basic in nature but zinc oxide and aluminium oxide are amphoteric. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Metals can form positive ions by losing electrons to non-metals. Metals are electropositive in nature. Metals combine with oxygen to form basic oxides. Aluminium oxide and zinc oxide show the properties of both basic as well as acidic oxides. These oxides are known as amphoteric oxides. Different metals have different reactivities with water and dilute acids. A list of common metals arranged in order of their decreasing reactivity is known as an activity series. Metals above hydrogen in the Activity series can displace hydrogen from dilute acids. A more reactive metal displaces a less reactive metal from its salt solution. Metals occur in nature as free elements or in the form of their compounds. The extraction of metals from their ores and then refining them for use is known as metallurgy. An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. The surface of some metals, such as iron, is corroded when they are exposed to moist air for a long period of time. This phenomenon is known as corrosion. Non-metals have properties opposite to that of metals. They are neither malleable nor ductile. They are bad conductors of heat and electricity, except for graphite, which conducts electricity. Non-metals form negatively charged ions by gaining electrons when reacting with metals. Non-metals form oxides which are either acidic or neutral. Non-metals do not displace hydrogen from dilute acids. They react with hydrogen to form hydrides. Alkali metals and their compounds Metals of first group are alkali metals. This group lies in the s-block of the periodic table of elements as all alkali metals have their outermost electron in an s-orbital. Lithium, sodium, potassium, rubidium and cesium are alkali metals. These metals are stored under kerosene or liquid paraffin’s to protect them from action of air. Sodium chloride (NaCl) is Commonly known as table salt Used in the manufacturing of sodium hydroxide and chlorine gas. It is used as a starting material in the manufacturing of caustic soda. It is used in the removing of ice from road, now a- days CaCl2 and MgCl2 are also used for this purpose. Sodium hydroxide (NaOH) is Used in the refining of bauxite material. Used in soap, dyes and artificial industries. Sodium bicarbonate (NaHCO3) is commonly known as baking soda. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Used for wool washing. Used in the fire extinguisher. Sodium carbonate (Na2CO3) is commonly known as washing soda. Used for softening of hard water. Mixture of sodium carbonate and potassium carbonate is known as Fusion mixture. Potassium hydroxide is Commonly known as caustic potash. It is used in the preparation of soft soap. Potassium superoxide KO2 is used in space capsules, submarines and breathing mask as it removes in carbon dioxide and carbon monoixide. Alkaline Earth Metals and their compounds The alkaline earth metals are six elements in column (group) 2 of the Periodic table. They are beryllium (Be),magnesium(Mg),calcium (Ca), strontium (Sr),barium (Ba),and radium (Ra). They have very similar properties: they are all shiny, silvery-white, somewhat reactive metal at same temperature and pressure. Mg(OH2) is known as milk of magnesia and use as an antacid. Calcium oxide is also known as quick lime. Also Used in the manufacturing of calcium chloride, cement and bleaching powder. Calcium sulphate (CaSO4) exists in three levels of hydration, i.e., anhydrous state (mineral name: "anhydrite") with the formula CaSO4 dihydrate (mineral name: "gypsum") with the formula CaSO4(H2O)2.hemihydrate with the formula CaSO4(H2O)0.5. It loses a part of water to form plaster of Paris. Plaster of Paris is a white powder which becomes hard on contact with water and is used in the manufacturing of statues. Some Important Metals Aluminium (Al): Ore of aluminium is bauxite. It is the third most abundant element in the earth’s crust. Used in the manufacturing of cooking utensils. Ammonal , a mixture of aluminium powder and ammonium nitrate is used as an explosive. Lead(Pb) Main ore of lead is galena. Use in the preparation of sulphuric acid through chamber process. Lead acetate is known as sugar of lead. Zinc(Zn): It is used in the galvanisation process to prevent the rusting of iron. Zinc sulphide is used in the preparation of X-ray screens. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Zinc oxide is known as philosopher wool. Mercury(Hg): It is the only metal which is liquid at room temperature. It forms alloys with all other metal except iron and platinum. Nickel(Ni): Silvery white soft metal. Used as anode in Edison batteries. Iron(Fe) Extracted from the haematite ore and do not occur in Free State due to its reactivity. Ferric chloride is used as stypic to stop bleeding from the cut. Ferrous sulphate is used in making blue black ink. Stainless steel: It is an alloy of iron, chromium and nickel. Used in making automobiles parts and utensils Non Metals: Non-metal may be solid, liquid or gas. Bromine is the only liquid non metals. Non metals are the elements that do not have the properties of the metals. They are soft, non lustrous, brittle ,non sonorous and poor conductor of heat and electricity.e.g. carbon, hydrogen, helium, neon krypton etc. Important Non metals Carbon: Carbon belongs to the group 14 of the periodic table. Carbon occurs both in free state as well as in combined state. Carbon has two crystalline allotropes diamond and graphite. Allotropes of Carbon: Diamond: Diamond is the hardest substance and is the bad conductor of electricity. Diamond is the purest form of the Carbon Used in making of jewellery and cutting glass. Graphite: Its an exception , it is a good conductor of heat and electricity. Used in nuclear reactor as a moderator. Compounds of Carbon: Carbon monoxide: It is colourless, odourless, neutral and highly poisonous gas in nature. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Combines with haemoglobin to form Carboxyhaemoglobin, which is not able to absorb oxygen as result leads to suffocation Wood fire or coal fire in a closed room leads to the formation of the carbon monoxide which leads to the death of the persons in the rooms. Carbon Dioxide: Occur in the air to the extent of 0.03-0.05 percent. Solid CO2 is known as dry ice. Dry ice is used is used in transport of perishable food material as it provides cold and inert atmosphere which helps in killing bacteria, fungi, modules etc. Carbon dioxide is used by the plants in the process of photosynthesis for the formation of oxygen. Carbides are the compound of carbon with metals or electro-negative elements. Silicon(Si) Silicon occurs in nature in the form of sand but never found in free state. This is a non-metallic element which also exhibits the characteristic of allotropy. This is the second most abundant element on the earth crust after oxygen Used as a superconductor in making computer chips. Silicon carbide is an artificial diamond called carborendum. Silica is also called sand which exist most abundantly in solid state in the nature and used in the production of glass, cement etc. Quartz is a crystalline form of SiO2. Nitrogen(N2) : Important constituent of air about 79% by volume. Used in the manufacturing of nitric acid, ammonia and other nitrogen compounds. As a refrigerant in liquid form. To provide inert atmosphere in different metallurgical operation. Used as preservative in the food packing. Compounds of Nitrogen: Ammonia: Most important compound of nitrogen. Prepared by Haber’s process. It is soluble in water and its aqueous solution is alkaline in nature. Used in refrigerator and manufacturing of fertilisers and explosives. Nitrous oxide(N2O) is used as laughing gas. The symbiotic bacteria present in the root nodules of leguminous plant convert the atmospheric nitrogen into compounds of nitrogen.e.g. Azobactor. Phosphorus(P): It is highly reactive non metal that why it does not occurs in free state. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Phosphorus is an essential constituents of bones, teeth, blood nerves and tissue. Bones contains 80% phosphorus. Oxygen Oxygen exist in two allotropic form that is in most stable diatomic form(O2) and in less stable triatomic form (O3) ozone. Oxygen is the supporter of combustion but it is non-inflammable. Oxygen dissolved in blood in the form of oxyhaemoglobin. Liquid oxygen mixed with freshly divided carbon is used in place of dynamite in coal mining. Ozone is formed by the action of UV rays from the Sun on Oxygen and protects the living beings by not allowing UV rays to reach the earth. Ozone is also used as germicide and disinfectant for sterilizing water and for detecting position of double bond in unsaturated organic compounds. Sulphur(S): Sulphur occurs in free state in volcanic areas. Suphur exists in five allotropic form. Sulphur is used in rubber industry for vulcanization of rubber. Sulphuric acid is also known as oil of vitrol or king of chemicals. Sulphuric acid is prepared by two process i.e. lead chamber process and contact process. Halogens: Halogens are placed in Group VII of the periodic table. Common halogens are chlorine, bromine, iodine, fluorine, etc. Halogens are highly reactive elements and therefore they do not exist in free state but exist only in combined form. Halogens have highest electron affinity so they act as strong oxidising agent. Their oxidising power decreases from fluorine to iodine. Chlorine always present in combined state in nature in the form of chlorides. Chlorine was first discovered by Scheele by the action of hydrogen chloride on manganese dioxide. Chlorine is used as an bleaching agent. Reacts with water to form HCL and HCIO. Used as disinfectant and oxidising agent Iodine is used as an antiseptic as tincture of Iodine. Used in the cure of Goitre. Main source of iodine is iodized salt. Turns starch solution blue. Metalloids: They have properties of both metals and non-metals. Six commonly known metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Typical metalloids have a metallic appearance but they are brittle and only fair conductor of electricity. Metalloids and their compounds are used in the manufacturing of alloys , biological agents, flames retarders, glasses, optical storage Some Important Ores of Metals Ores - Those minerals from which the metals are extracted commercially and economically and with minimum effort are called Ores of Metals. Name of Elements Ores Chemical Formulae 1. Aluminum (Al) (a) Bauxite (b) Corundum (c) Al2O32H2O Al2O3 Na3AlF6 Kryolite 2. Iron (Fe) (a) Hematite (b) Magnetite (c) Fe2O3 Fe3O4 FeS2 IronPyrite 3. Copper (Cu) (a) Copper Pyrite (b) Copper CuFeS2 Cu2S Glance (c) Malachite 2CuCO3Cu(OH)2 4. Zinc (Zn) (a) Zinc Blende (b) Calamine ZnS ZnCo3 5. Sodium (Na) (a) Rock Salt (b) Sodium NaCl Na2CO3 Carbonate 7. Lead (Pb) (a) Galena (b) Anglesite PbS PbCl2 9. Silver (Ag) (a) Silver Glance Ag2S 10. Gold (Au) (a) Calve rite (b) Sybarite AuTe2 AgAuTe2 11. Mercury (Hg) (a) Cinnabar (b) Calomel HgS Hg2Cl2 13. Calcium (Ca) (a) Lime Stone (b) Dolomite CaCO3 MgCO3CaCO3 14. Phosphorous (P) (a) Phosphorite (b) Floreopetite Ca3(PO4)CaFe2 3Ca3(PO4)CaFe2 Noble Gases: Helium, neon , argon, krypton , xenon and radon are known as inert gases or noble gases. These elements have completely filled valence shell and so these do not form chemical bonds. These are always found in free state but radon is not present in nature. In atmosphere argon is the most abundant noble gas but in universe helium is the most abundant gas. Mixture of Helium and Oxygen is used for artificial breathing of Asthama patients and by sea drivers. Helium is used as pressuring agent in rockets to expel liquid oxygen and liquid hydrogen. Neon is used in neon discharge lamp and signs for advertising purposes. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Xenon is also known as stranger gas and combined mixture of xenon and krypton is used in high intensity photographic flash tubes. Radon is used in the preparation of ointment for the treatment of cancer. A mixture of argon and nitrogen is used in electric bulb. Krypton is used in high efficiency miner’s cap lamps. Acids Bases and Salts Acids is a substance which produces hydrogen ions in aqueous solution e.g. HCL, sulphuric acid. They turn blue litmus, red. - Base is a substance which produces Hydroxide ion (OH ) in aqueous solution e.g. sodium hydroxide and ammonium hydroxide etc. They turn red litmus, blue. Pickels are always kept in glass jar because acid present in them reacts with metal to produce hydrogen gas. Acids are the substance, which have sour taste and turn blue litmus red. These are good conductor of electricity in aqueous solution. Acids which are obtained from plants and animals are called organic acid e.g. lactic acid, oxalic acid, acetic acid. Acids which are obtained from minerals are called mineral acids, e.g. sulphuric acid and phosphoric acid. Litmus solution is a purple dye, which is extracted from lichen, a plant belonging to the division Thallophyta, and is commonly used as an indicator. When the litmus solution is neither acidic nor basic, its colour is purple. Synthetic indicators such as methyl orange and phenolphthalein to test for acids and bases. There are some substances whose odour changes in acidic or basic media. These are called olfactory indicators The strength of acids and bases depends on the number of H+ ions and OH– ions produced, respectively. Acids that give rise to more H+ ions are said to be strong acids, and acids that give less H+ ions are said to be weak acids. The concept of pH was first introduced by the Danish chemist Soren Sorensen in 1909 and revised to the modern pH in 1924. The pH scale ranges from 0 to 14. A neutral solution has a pH of 7. It is neither an acid or a base. An acidic solution is indicated by a pH below 7, while a basic solution is indicated by a pH above 7. The solutions which resists the change in its pH value on addition of a small amount of acid or base are called buffer solutions. When acidic and basic solutions are mixed in proper proportion than their own nature is destroyed and Salt is formed. It is is called as neutralisation reaction. Acetic acid Dilute acetic acid is used as vinegar and concentrated acid is used as solvent. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Prepared by the fermentation process Oxalic Acid It is found in spinach. It is used to remove ink stains from the cloth. Its salt potassium ferrous oxalate is used in the photography. It occurs in rhubarb, sorrel and other plant of oxalic acid group in the form of potassium salts. Lactic Acid It is a monohydroxy acid, present in milk When we do vigorous physical activity lactic acid is produced which causes pain in muscles. Tartaric Acid It occurs in grapes, tamarind and berries. Used in in dyeing industry and making baking powders. Rochelle salt(sodium potassium tartrate) is used in the preparation of Fehling solution. Citric Acid In Free states it is found in citrus fruit such as lemon, lime, orange and galgal. Used in making beverages and as a mordant in dying and calico –printing. Acetoacetic Acid It is a colourless liquid, on decomposition it gives acetone and CO2. It occurs in excess in urine of diabetic patients. Material pH Value Blood 7.3 – 7.5 Tears 7.4 Saliva 6.5 – 7.5 Urine 5.5 – 7,5 Coffee 4.5 – 5.5 Beer 4.0 - 5.0 Wine 2.8 – 3.8 Vinegar 2.4 – 3.4 Organic Compounds and Hydrocarbons These are compounds of only hydrogen and carbon. These can be classified into the three types Saturated hydrocarbons: Methane is the first member of this group. They are bonded by only single bond. These are also called alkanes and paraffin and have general formula CnH2n+2 where n can have any value i.e. n=1, 2, 3….. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Unsaturated hydrocarbons: These hydrocarbons contain at least one double bond or one triple bond. They are popularly known as alkenes for double bond and alkynes for triple bond. General formula is CnH2n for alkenes and CnH2n-2 for alkynes. Aromatic hydrocarbons: They have ring structure with alternate double bonds, e.g. Benzene. Methane is popularly known as marsh gas damp fire. Paddy field or rice agriculture is the biggest source of this gas. Its mixture with air is explosive in nature. It is colourless and odourless gas. Natural gas contains 90% methane and some parts of butane and propane etc. Due to this explosion occur in the mines.Used in the preparation of Carbon Black, used in the tyre industry. Bio-gas is a mixture of gases produced during decay of biomass in the absence of oxygen. Main constituent of the Biogas is Methane about 75%, carbon 25% and small proportion of hydrogen and nitrogen, and hydrogen sulphide. It burns without producing the smoke. Important Compounds of Hydrogen and Carbon: Ethane (C2H6): used as a fuel and in making some organic compounds. Its hexachloro derivative is known as artificial camphor. Butane (C4H10): main constituent of LPG, used as fuel. As LPG doesn’t have any smell so to detect in case of leakage ethyl mercaptan is mixed with butane. Ethylene (CH2=CH2): Used for the preparation of the mustard gas. It is used as an anaesthetic for the preservation and artificial ripening of green fruits and also used in the manufacture of the PVC. Acetylene: A colourless gas with sweet smell. Sweet smell is due to the presence of the phosphine present in it as an impurity. Benzene (C6H6): It is an aromatic hydrocarbon. It was discovered by Faraday. Used for the destructive distillation of the whale oil, and also used as a solvent for the fats and resins. It is also used in dry-cleaning and as motor fuel with the name benzol. Toluene (C6H5CH3): Obtained with the dry distillation of Tolu Balsam. Used in the manufacturing of the TNT explosive, drugs, dyestuffs and saccharin. Combination of petrol, benzene and toluene is used as antifreeze. Functional group: It is an atom or group of atom responsible for the chemical properties of the molecule. –OH is alcoholic group, –CHO, –O– is either group. ALCOHOLS (OH Group) Methyl alcohol (CH3OH) is known as wood spirit or wood naptha. It is used for the denaturing of alcohol (methylatd spirit is denatured ethyl alcohol). It is also used as alcohol-petrol fuel, automobile antifreeze mixtures and in the manufacturing of drugs, dyes and perfumes etc. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Ethyl alcohols (C2H5OH) is known as alcohol, spirit of wine or grain alcohol. It is used as solvent in paint industry. Ethylene glycol is used as a antifreeze in automobile radiator and as a cooling agent in aeroplanes instead of water. Its dinitrate is used as an explosive with trinitroglycerine. Glycerol is present in almost all the animal and vegetable oil and fats as glycerides.It is hygroscopic in nature and used in the manufacturing of the cosmetic and transparent soaps, as a lubricant for watches and clocks. Phenol (C6H5OH) is commonly known as carbolic acid or benzenol and prepared by the middle oil fraction of Coal Tar. Used in the preparation of drugs such as aspirin, salicylic acid and phenacetin. ALDEHYDES Formaldehydes (HCHO) : Its 40% dilute solution is known as formalin, used as insecticide, germicide and preservative for biological specimen. It is used in leather industry for tanning and in manufacturing of synthetic dyes and Bakelite. KETONES Acetone or Dimethyl ketone (CH3COCH3) is the fist member of keton series. It Is one of the constituent of the nail polish. Hydrogen Derivatives of Hydrocarbons Ethyl bromide is colourless and used as a local anaesthetic and in organic synthesis. Chloroform (CHCL3) was discovered by Leibig, used as the anaesthetic in surgery. Always stored in the dark coloured bottle as it get oxidised with the sunlight and form a poisonous gas known as Phosgene. It reacts with concentrated HNO3 to form Chloropicrin, a poisonous gas used in the war. Carbon tetrachloride (CCL4) is used as an fire extinguisher, used as an solvent for the fats, oils in the industry. The chlorofluorocarbon compounds of methane and ethane are collectively known as Freon. They are produced by the refrigerator, A.C and propellants. They causes the depletion of Ozone. Dichloro diphenyl trichloro ethane (DDT): Discovered by Paul Muller and it is used as an insecticide, widely used against the mosquito and lice. It is highly stable and is not decomposed easily in the environment that why it is banned in several country. P-dichloro benzene Used as insecticide, germicide and in deodorant and moth repellent. Perfluro carbons (PFC) are used as an electric insulator, lubricants, dielectric, heat transfer media in high voltage. Important Chemical Reactions : Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Oxidation and Reduction : These processes take place simultaneously. Oxidation : is a chemical change involving ga in of oxygen or any other negative element or loss of hydrogen of any other electro-positive element. Reduction is a chemical change involving loss of oxygen or any other electronegative element or gain or hydrogen or any other electropositive element. Exothermic and Endothermic Reactions : Chemical reactions are accompanied by evolution or absorption of heat. Exothermic Reaction liberate heat while endothermic absorb heat. Corrosion The oxidative deterioration of a metal surface by the action of environment is called corrosion, an electrochemical process. When iron exposed in to air, iron surface turns brown due to the formation of hydrated ferric oxide (Fe203.xH20) which is also called rust, Silver - Surface turns black due to the formation of silver sulphide (Ag2S) Renewable Non-renewable Natural Resources Renewable resources are available in large excess, i.e., never ends, e.g, air, sunlight etc. Non-renewable resources are available in limited quantity and end, if used excessively, after a limited period of time. e.g., mineral, coal, petroleum, natural gas etc. Fuels The substance, which produce heat and light on combustion are called fuels. A strong foul smelling substance, called ethyl mercaptan is added to LPG to detect its leakage as LPG is an odourless gas. Coal Coal is obtained by carbonization of vegetable matter and is available in different varieties: Peat contains 60% C Lignite or Brown Coal contains 70% C Bituminous contains 60 to 80 % C Anthracite Coal contains 90% C On heating coal at a temperature in the range of 1270-1675oC in the absence of air, it decomposed to give the following products. Coke: It is the solid residue left after the distillation of coal; it is used as a fuel and as a reducing agent in different metallurgical process. Coal Tar: It is a thick black colour viscous liquid. It is used in various industries such as dying and drugs and mainly used in the metalling of road. Now a day’s bitumen a petroleum product is used in the metalling of road. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Fractional distillation of Coal Tar produces the following products: light oil, middle oil or carbolic oil, heavy oil or creosote oil, green oil or anthracene oil and pith. Petroleum: Petroleum is a fossil fuel. It is formed under beneath the earth surface by the decomposition of dead remains of organism living in the sea. Over the year these dead remains converts into the petroleum and natural gas due to the absence of air, high temperature and high pressure. Knocking Knocking is a metallic sound produced in engine due to low quality of petrol. Knocking can be reduce by adding antiknock compound. TetraethylLead (TEL) and Benzene-Toluene-Xylene(BTX) are common antiknock compounds. TEL creates pollution, so its use has been stopped in India. Rocket Fuel The fuel used in rockets is called rocket propellant. It is a combination of an oxidiser and a fuel which on combination releases large quantities of hot gas. Propellants are of following types: Liquid propellants: They are alcohol, liquid hydrogen, liquid ammonia, kerosene oil, nitromethane and hydrogen peroxide. Solid propellants: Example of solid propellants are polybutadiene and acrylic acid used along with oxidiser such as aluminium per chlorate, nitrate or chlorate. Hybrid propellant: They consists of a solid fuel and liquid oxidisers. Fuel Composition Sources Water Gas Carbon monoxide (co) + By passing stream over hydrogen(h2) red hot coke Producer Gas Carbon monoxide (CO) + Nitrogen By passing insufficient air (N2) over red hot coke Coal Gas Hydrogen + methane + Ethylene + By fractional distillation Acetyene + CO +Nitrogen Natural Gas Methane(83%) + Ethane From petroleum Liquefied Butane (CH4) 95% From petroleum Petroleum Gas (LPG) Compressed Methane (CH4) 95% From petroleum Natural Gas (CNG) Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Biogas or Gobar Methane (CH4) + Carbon dioxide From organic wastes Gas (CO2) + Hydrogen (H2)+ Nitrogen (N2) Flame contains three parts : Innermost Part- which is black due to the presence of unburned carbon particles- has lowest temperature. Middle part – is yellow due to incomplete combustion of fuel. Outermost part- which is blue due to complete combustion of fuel is the hottest and used by goldsmith to heat the gold. Fire Extinguishers Water extinguishes fire because as it evaporates, the vapours surround the burning substance, cutting off the oxygen supply, thus inhibiting burning process. In case of electrical or oil (petrol) fires, water cannot be used as extinguisher. This is because water is a conductor of electricity and heavier than oil. Thus, oil floats over it and continues to burn. Carbon dioxide, which is generated by the reaction of baking soda with acid, is used extinguish electrical or oil fires. Quality of petrol is measured in terms of octane number and that of diesel in terms of cetane number. Safety Matches In safety matches, the stick consists of mixture of antimony trisulphide and potassium chlorate at its one end. The box side contains a mixture of powdered glass and phosphorus. Battery Battery is a device, used to convert chemical energy into electrical energy and is of two types (i) Primary batteries (non-rechargeable) act as galvanic cell, e.g., dry cell, mercury cell etc. (ii) Secondary Batteries: (rechargeable) Act as galvanic as well as voltaic cell E.g., lead storage battery, nickel cadmium battery etc. Plaster of Paris It is chemically calcium sulphate hemihydrate (CaSO4.1/2H2O) and is prepared by heating gypsum – which is calcium sulphate dehydrate (CaSO4.2H2O) at 373 K. On Mixing with water, plaster of Paris further sets into a hard solid, called gypsum. Thus, it is used to plaster fractured bones, for making toys, materials for decoration and for making surfaces smooth. Cement: Discovered by English Mason, Joseph Aspdin, he named it Portland cement. Limestone, clay and gypsum are some important raw material that is required in the manufacturing of the cement. When cement is mixed with water and left for some time, it becomes a hard mass. This is known as setting of Cement, it is an exothermic process that’s why sprinkling of water is done for few days for a new construction. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Mortar is a mixture of cement, sand and water; it is used for plastering walls and binding bricks. Concrete is a mixture of cement, sand, gravel and water. It is used for the construction of floors. Structure having iron rods embedded in wet concrete is known as reinforced concrete. Portland Cement It is a complex mixture of silicates and aluminates of calcium with small amount of gypsum. Raw materials used for the manufacture of Portland cement are limestone and clay. The composition of Portland cement is calcium oxide (50-60%), alumina (5-10%), and magnesium oxide (2- 3%). Gypsum is added to cement to decrease its rate of setting. In cement, if line is in excess, cement cracks during setting and if lime is less, cement is of weak strength. Mortar a mixture of sand, cement and water is used for joining bricks and plastering walls. Concrete—a mixture of gravel, sand, cement and water is used for flooring and making roads. Reinforced Concrete Cement (RCC)— which is concrete with steel bars and wires is used for constructing roofs, bridges and pillars Glass: It is a super cooled liquid of silicate, it is amorphous in nature. Raw material used for the formation of glass is sodium carbonate, calcium carbonate and sand. Sudden cooling of molten glass make it brittle if cooled very slowly make it opaque. The process of slow and uniform cooling is called annealing. When glass is attacked by hydrofluoric acid, it is called etching of glass. Coloured glass is obtained by adding certain metallic oxides or salts to the molten glass. Substance Used Colour Produced Cuprous Oxide Red Cobalt Oxide Blue Ferrous Oxide Green Potassium Dichromate Green or Greenish Yellow Cadmium Sulphide Yellow Carbon Amber Colour Types of glasses and their uses Soft glass (Soda Glass): Mixture of sodium or calcium silicate. Used in making of glass, mirrors and common glass ware etc. Hard Glass: Mixture of potassium and calcium silicates. Resistant to the action of acids and used for making hard glass. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Pyrex glass (Borosilicate glass) : Used by fusing a mixture of sand, lime, borax and alkali carbonates. Used in making of pharmaceuticals containers. Glass fibre: Glass wool is an excellent heat insulator. Used in insulating material in oven, refrigerator. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Cell And Cell Structure Human body , like body of any other living organism is made up of very small blocks called cells The Cell was discovered by Robert Hooke in 1665.A Cell is a functional and structural unit of all living beings. Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory. Cell theory has become the foundation of biology and is the most widely accepted explanation of the function of cells. The three tenets to the cell theory are as described below: 1. All living organisms are composed of one or more cells. 2. The cell is the basic unit of structure and organization in organisms. 3. Cells arise from pre-existing cells. The three basic characteristics of Cells : (i) They contain a set of genes : All cells contain genetic material in the form of either DNA or RNA, which contains genes. Genes have coded information for the regulation of cellular functions and for the production of new cells. (ii) They contain a limiting plasma membrane : Every type of cell is bounded by a plasma membrane which is a living, ultra-thin membrane of molecules of lipids and proteins. This membrane permits controlled exchange of matter and energy with the cell’s external world. (iii) They contain a metabolic machinery : All cells contain acytoplasm having various cellular organelles such as mitrochondria, choroplasts, ribosomes, endoplasmic recticulum, Golgi apparatus. A cell is made up of a life giving substance called protoplasm. Protoplasm is an aggregate of molecules of various chemicals such as water, ions, salts and organic molecules. Organic molecules of protoplasm are proteins, carbohydrates, fats (lipids) and nuclic acids (DNA and RNA). The three major functional regions of a cell are : The plasma membrane, The nucleus and The cytoplasm A gene is a unit of hereditary information. Gene is inherited from one generation to the next and determines an observable characteristic or trait of an organism. Genes have coded information of parents to their progeny so that the children remain exactly like their parents. Generally a gene is made of DNA , but sometimes it is made of RNA molecule. Character Prokaryotic Cell Eukaryotic Cell 1. Occurrence Found in Bacteria, blue-green Found in Protista, Fungi, plants algae and Mycoplasma and animals 2. Nucleus Nucleus is absent Nucleus is present Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) 3. Cell Membrane bound cell Cell organelles such as Organelles organelle are absent mitochondria, plastids, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, etc. are present 4. Size Size of the Cell is generally Size of the cell is generally large small (1-10 μm) (10-100 μm) 5. It contains single It contans more than one Chromosomes chromosome. chromosome. 6. Cell Division Cell division takes place by Cell division occurs by mitosis fission or budding or meiosis. Tissue is a group of cells of the same origin, which are similar in structure and function. In multicellular organisms, tissues provide protection, mechanical strength and give highest possible efficiency to the organisms. The types of simple tissues are : (i) Parenchyma (ii) Collenchyma (iii) Scelerenchyma. Plant Tissues Animal Tissues 1. Tissue organization is towards 1. Tissue organization is towards stationary or fixed habit. active locomotion. 2. Dead supportive tissues are more 2. Liviing tissues are more common. abundant. 3. Animals need more maintenance 3. Plants need less maintenance energy. energy. 4. Such a differentiaiton is absent. 4. There is differentiation of merimatic and permanent tissues. 5. Organization is simple. 5. Organization is complex. 6. Growth is limited to certain 6. Growth is not limited in animals. regions. There are mainly two types of tissues in the plants : (i) Meristematic tissues (ii) Permanent tissues. Meristematic tissues are growth tissues and are found in those regions of the plant that grows, for example, the root tip, shoot tip and cambium. These tissues are living and bring about in increase in the Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) length and girth of the plant. According to these positions in the plant, meristems are apical, lateral and intercalary. Some of the important characteristics of meristematic tissues are : (i) The cells of meristematic tissue are similar to structure and have thin cellular cell walls. (ii) The meristematic cells may be spherical, oval polygonal or rectangular in shape. (iii) Each meristematic cell contains dense or abundant cytoplasm and a single large nucleus. (iv) The meristematic cells are compactly arranged and do not contain any intercullar space between them. (v) The meristematic cells may or may not contain vacuoles. Some of the important functions of meristematic tissues are : (i) Meristematic tissues have the ability to divide, ehnce they continuously produce new cells which keep differentiating to form specialized cells of the plant. (ii) The cells of the root tip and shoot tip bring about an increase in length of the plant. (iii) The cells in the lateral region, i.e., cambium bring about an increase in girth of the plant. Some of the important characteristics of permanent tissues are : (i) Permanent tissues do not divide as they have lost the power of division. (ii) They have a definit form and size. (iii) They are differentiated cells and carry out specific functions. (iv) They may be living or dead cells. (v) They may have thin or thick cell walls. (vi) The cells are large with vacuolated cytoplasm. The permanent tissues are classified into two groups - simple and complex which are further divided into various types as under : (i) Simple Permanent tissues are of three types - Parenchyma, collenchyma and scelerenchyma. (ii) Complex permanent tissues are of two types - xylem and phloem. All the living organisms need energy to perform various life processes. They get this energy from food. Food is a kind of fuel which provides energy to all living organisms. The living organisms use the chemical energy. They get this chemical energy from food through chemical reactions. Nutrition is a process of intake of nutrients like carbohydrates, fats, proteins, minerals, vitamins and water by an organism as well as the utilization of these nutrients by the organism. There are mainly two modes of nutrition - autotrophic and heterotrophic. Autotrophic nutrition is that mode of nutrition in which an organism synthesizes its own food from the simple inorganic materials like CO2 and water by utilizing the sunlight energy. For example, green plants and autotrophic bacteria. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Heterotrophic nutrition is that mode of nutrition in which an organism cannot synthesize its own food from simple inorganic materials like carbon dioxide and water and depends on other organisms for its food. All the animals, most bacteria and fungi have heterotrophic mode of nutrition. Saprotrophic nutrition is that nutrition in which an organism obtains its food from dead and decaying organic matter of dead plants, dead animals and rotten bread etc. The organisms having sprotrophic nutrition are fungi like moulds, mushrooms, yeast, etc. and many bacteria. The parasitic nutrition is that nutrition in which an organisms derives its food from the body of another living organism (called its host). Parasitic mode of nutrition is observed in several fungi, bacteria, a few plants like Cuscuta and some animals like Plasmodium and roundworms. The holozoic nutrition is that nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion, the ingested food is digested and then absorbed into the body cells of the organism. The undigested and unabsorbed part of the food is thrown out of the body of the organism by the process of egestion. For example, human beings and most of the animals like dogs, cat, cattle, frog, fish and amoeba etc. have holozoic mode of nutrition. The process of synthesis of food or glucose from carbon dioxide and water in the presence of chlorophyll by green plants, is called photosynthesis. In the process oxygen is liberated : 6CO2 + 6H2O C6H12O6 + 6O2 The conditions necessary for photosynthesis to take place are : Sunlight, Chlorophyll, Carbon dioxide and water. The food prepared by green leaves of a plant is in the form of a simple sugar called glucose. This glucose food is made in the leaves is then sent to different parts of the plant. The simple carbohydrates (like glucose) made by the leaves of a plant during photosynthesis which is not used by the plant immediately is stored in the plant in the form of a complex carbohydrate called starch. This starch is stored in the leaves of the plants. This stored starch acts as the internal energy 'reserve’ which can be used by the plant as and when required. Human Digestive System The various organs of the human digestive system are : Mouth, Oesophagus, Stomach, small intestine and large intestine. The glands associated with the digestive system, viz., slivary glands, liver and pancreas also form part of the human digestive system. The mouth cavity contains teeth, tongue and salivary glands. When we put food in our mouth, the teeth cut the food into small pieces, chew and grind it. The salivary glands produce a watery liquid called 'saliva'. Our tongue helps in mixing saliva with food and wets it. The wetted food can be swallowed more easily. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) The saliva contains an enzyme called salivary amylase which breaks down the complex starch molecules present in food into sugar. From the mouth, the food enters into the food pipe called oesophagus. The peristaltic movements of food pipe take this food into stomach. The food is further digested in the stomach. The muscular walls of the stomach churn the food and break it into still smaller pieces to form a semi-solid paste. The glands present in the walls of the stomach secrete gastric juice which mixes with the food in the stomach. The gastric juice contains three substances: hydrochloric acid, enzyme pepsin and mucus. Hydrochloric acid creates an acidic medium which is necessary for the action of pepsin on proteins. Pepsin is the protein digesting enzyme. Pepsin breaks the proteins present in food into smaller molecules. Mucus protects the inner lining of the stomach from hydrochloric acid. From the stomach, the partially digested food now goes into the small intestine. Small intestine is the site of complete digestion of carbohydrates, proteins and fats present in food. The small intestine receives the secretion of two glands, liver and pancreas, for the purpose of digestion. Liver secretes bile which is an alkaline liquid. Bile makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it. Bile salts also break the large fat globules present in our food into small globules making it easy for the enzymes to act and digest them. Pancreas secretes pancreatic juice which contains digestive enzymes like pancreatic amylase, trypsin and lipase. Amylase breaks down the starch, trypsin digests the proteins and lipase breaks down the emulsified fats. The walls of small intestine contain glands which secrete intestinal juice. The enzymes present in intestinal juice finally convert the complex carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol. All these are small, water soluble molecules of digested food. The digested food is absorbed by the walls of the small intestine. The inner lining of small intestine has large number of tiny, finger-like projections, called villi, which help in the absorption of food by increasing the surface area. The digested food absorbed through the walls of small intestine goes into our blood. The blood carries digested food to each and every cell of the body where it is utilised for obtaining energy, building up new tissues and repairing of old tissues. The unabsorbed food goes into large intestine. The large intestine absorbs water from the undigested food through villi making it almost solid. This undigested food is removed from the body through anus in the form of stool. An ulcer on the inner membrane lining of the stomach is called peptic ulcer. Peptic ulcer is a kind of digestive ulcer. Peptic ulcer is caused by the higher acidity of gastric juice secretions. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) The length of small intestine differs in various animals because they eat different types of food. For example, herbivorous animals like cow (which eat grass) need a longer small intestine to allow the cellulose (present in grass) to be digested. This is because cellulose is quite difficult to digest. On the other hand, carnivorous animals like tiger (which eat meat) have a shorter small intestine because meat is easier to digest. Respiration The process of releasing energy from food is called respiration. When oxygen burns the food in the cells of the body to release energy, then carbon dioxide and water are produced as waste products which are to be eliminated from the body. The process of respiration involves taking in oxygen into the cells, using it for releasing energy by burning food, and then eliminating the waste products (CO2 and water) from the body. Breathing organs of : (i) Fish - Gills (ii) Mosquito - Spiracles and Trachea (iii) Earthworm - Moist skin (iv) Dog – Lungs Lenticel is an area in a woody stem where the cells are loosely packed allowing the gas exchange to take place between the air and the living cells of the stem. Lenticels are present in the hard, woody stems of large plants or trees. Some old portions of the roots also have lenticels. Stomata are the pores on the lower surface of the plants through which there is an exchange of gases between the air and the cells of the leaves. Water vapour from the leaves also goes out through stomata during transpiration. The lower surface of all the leaves of a plant has tiny pores called stomata. The exchange of respiratory gases in the leaves takes place by the process of diffusion through stomata. Oxygen from air diffuses into a leaf and reaches all the cells where it is used in respiration. The carbon dioxide produced during respiration diffuses out from the leaf into the air through the same stomata. In aerobic respiration, glucose (a six carbon molecule) is first broken down into pyruvate (a three carbon molecule) and then the pyruvate is oxidised completely by oxygen to form carbon dioxide and water, releasing a lot of energy. In anaerobic respiration, glucose is first broken down into pyruvate and then pyruvate breaks up in the absence of oxygen to form ethanol and carbon dioxide releasing lesser amount of energy. The oxidation of glucose to pyruvic acid is called glycolysis. It occurs in the cytoplasm of a cell. This conversion does not require oxygen. During glycolysis, one molecule of glucose gives two molecules of pyruvic acid. Sometimes, when there is a lack of oxygen in our muscle cells, (as happens during excessive exercise) another pathway for the break-down of pyruvate is taken. Here the pyruvate is Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) converted into lactic acid which is also a three-carbon molecule. This build-up of lactic acid in our muscles during sudden activity causes cramps. Diffusion is the movement of molecules of gases, liquids and solutes from a region of higher concentration to the region of lower concentration till there is uniform concentration in the available space. Diffusion is the main process by means of which transport of materials occurs in algae, Amoeba, Euglena, Paramecium, Hydra and sponges. Osmosis is a special type of diffusion. When two solutions of different concentrations are separated by a selectively permeable membrane, the water moves from region of lower concentration to the region of higher concentration till a state of equilibrium is reached. The two transport systems of plants are ‘Xylem’ and ‘Phloem’. Xylem carries water and minerals. Phloem carries the food materials which the plant makes. Phloem also carries the hormones made by the plants in their root and shoot tips. Functional xylem cells are dead while the functional phloem cells are alive. Food molecules are transported to all part of the plants through upward or downward movement within the phloem. Transport of food from leave to other part of the plant is termed as translocation. Within the lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures which are called alveoli. The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli contain an extensive network of blood-vessels. When we breathe in, we lift our ribs and flatten our diaphragm, and the chest cavity becomes larger as a result. Because of this, air is sucked into the lungs and fills the expanded alveoli. The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body. During the breathing cycle, when air is taken in and let out, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released. Blood Blood is a connective tissue. It has a fluid matrix called plasma with red cells, white cells and platelets floating in it. Blood is red because it contains a red pigment called haemoglobin in its red cells. The blood flows through three types of blood vessels, viz., arteries, veins and capillaries. Circulation of blood is responsible for transportation of : (i) nutrients (ii) respiratory gases (iii) waste products (iv) hormones and enzymes and(v) ion from one part of the body to the other. An adult human body contains 5.5 to 6 litres of blood. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Plasma is a colourless liquid. It contains water (about 90%), inorganic and organic substance. The RBCs, WBCs and platelets also float in plasma. There are inorganic salts (0.9%). The organic substances are glucose, amino acids, proteins, hormones, digested and waste excretory products. Plasma carries all these dissolved substances from one part of the body to another. The blood proteins are fibrinogen, albumin, globulin and prothrombim. RBCs (Erythrocytes) carry oxygen from the lungs to all the cells of the body. RBCs contain Haemoglobin which is responsible for carrying oxygen from lungs to body tissues and carbon dioxide from body tissues to the lungs. RBCs are circular in shape. They do not have nuclei. The life span of RBCs is 120 days. RBCs are produced in bone marrow. Dead RBCs are stored in spleen. Here they are converted into WBCs. WBCs (Leucocytes) fight infection and protect the body from diseases. They fight against germs and other foreign bodies which causes disease. Some WBCs eat up the germs like bacteria while others produce ‘antibodies’ to fight against infections. Thus WBCs manufacture antibodies which are responsible for providing immunity. WBCs are either spherical in shape or irregular in shape. They have a nucleus though the shape of the nucleus is different in different types of WBCs. Platelets are the tiny fragments of special cells formed in bone marrow. They do not have a nuclei. Platelets help in the coagulation of blood in a cut or wound. Functions of blood : (i) Blood carries oxygen from the lungs to different parts of the body. (ii) Blood carries carbon dioxide from the body cells to the lungs for breathing out. (iii) Blood carries digested food from the small intestine to all the parts of the body. (iv) Blood carries hormones from the endocrine glands to different organs of the body. (v) Blood carries waste products called urea from the liver to the kidneys for excretion in urine. (vi) Blood protects the body from diseases. This is because WBCs kill the bacteria and other germs which cause diseases. (vii)Blood regulates the body temperature. (viii) The plasma proteins act as buffer system and maintain a required pH of the body tissues. (ix) The blood maintains water balance to constant level by distributing uniformly over the body. In case of injury, the blood vessels may get rupture. The cut bleeds for a while and then blood changes into thick jelly called a clot. The clot closes the rupture blood vessel and prevents further loss of blood. Later, the blood clot dries and forms a ‘scali’ which prevents germs and dirt from entering the wound. Lymph Lymph another type of fluid involved in transportation. Through the pores present in the walls of capillaries some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form the tissue fluid or lymph. It is similar to the plasma of blood but colourless and contains less protein. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Lymph carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood. The Heart The heart is a muscular organ which is as big as our fist. Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood containing carbon dioxide. The carbon dioxide-rich blood has to reach the lungs for the carbon dioxide to be removed, and the oxygenated blood from the lungs has to be brought back to the heart. This oxygen-rich blood is then pumped to the rest of the body. Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, expands, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body. De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it expands. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. Since ventricles have to pump blood into various organs, they have thicker muscular walls than the atria do. Valves ensure that blood does not flow backwards when the atria or ventricles contract. The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature. In animals that do not use energy for this purpose, the body temperature depends on the temperature in the environment. Such animals, like amphibians or many reptiles have three-chambered hearts, and tolerate some mixing of the oxygenated and de-oxygenated blood streams. Fishes, on the other hand, have only two chambers to their hearts, and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body. On the other hand, it goes through the heart twice during each cycle in other vertebrates. This is known as double circulation. The force that blood exerts against the wall of a vessel is called blood pressure. This pressure is much greater in arteries than in veins. The pressure of blood inside the artery during ventricular systole (contraction) is called systolic pressure and pressure in artery during ventricular diastole (relaxation) is called diastolic pressure. The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg. Blood pressure is measured with an instrument called sphygmomanometer. High blood pressure is also called hypertension and is caused by the constriction of arterioles, which results in increased resistance to blood flow. It can lead to the rupture of an artery and internal bleeding. Arteries are the vessels which Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. Veins collect the blood from different organs and bring it back to the heart. They do not need thick walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows only in one direction. On reaching an organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls which are one-cell thick and are called capillaries. Exchange of material between the blood and surrounding cells takes place across this thin wall. The capillaries then join together to form veins that convey the blood away from the organ or tissue. Excretory System The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra. The purpose of making urine is to filter out waste products from the blood. Just as CO2 is removed from the blood in the lungs, nitrogenous waste such as urea or uric acid are removed from blood in the kidneys. The basic filtration unit in the kidneys, like in the lungs, is a cluster of very thin-walled blood capillaries. Each capillary cluster in the kidney is associated with the cup-shaped end of a tube that collects the filtered urine. Each kidney has large numbers of these filtration units called nephrons packed close together. Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. The amount of water reabsorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control, as we have discussed elsewhere. As a result, we can usually control the urge to urinate. Kidneys are vital organs for survival. Several factors like infections, injury or restricted blood flow to kidneys reduce the activity of kidneys. This leads to accumulation of poisonous wastes in the body, which can even lead to death. In case of kidney failure, an artificial kidney can be used. An artificial kidney is a device to remove nitrogenous waste products from the blood through dialysis. Reproduction The production of new organisms from the existing organisms of the same species is known as reproduction. Reproduction is essential for the survival of a species on this earth. It ensures continuity of life on earth. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) The two types of reproduction are : (i) Sexual reproduction (ii) Asexual reproduction. In asexual reproduction, the offspring arises from a single parent. The production of a new organism from a single parent without the involvement of sex cells is called asexual reproduction. In this type of reproduction, a part of the parent organism separates off and grows into a new organism. For example, binary fission in Amoeba; budding in hydra; spore formation in Rhizopus fungus, etc. The production of a new organism from two parents by making use of their sex cells is called sexual reproduction. In sexual reproduction, the sex cell of one parent fuses with the sex cell of the other parent to form a new cell called ‘zygote’. This zygote then grows and develops to form a new organism. The humans, fish, frogs, cats and dogs and most of the flowering plants reproduce by the method of sexual reproduction. The process of reproduction results in the production of offsprings which have the same characteristics as the parents. The progeny inherits the blue print of body design in the form of DNA. Therefore, DNA copying is essential for reproduction. DNA is the genetic material of all living beings. It carries information for all the structural and functional features of an organism. DNA copying is the process of generating the set of information for producing more individuals with same basic features though errors do occur rarely resulting in some changes. For sexual reproduction to occur, a male gamete must combine with a female gamete. The fusion of a male gamete with a female gamete form a zygote during the sexual reproduction, is called fertilisation. The male gamete of an animal is called sperm and the female gamete animal is called ovum (or egg). The process of fertilisation produces a new cell called zygote. The zygote grows and develops to form a new baby. An organism which possesses only one kind of reproductive organs in its body is called a unisexual organism. For example, humans, frogs, birds, fishes and reptiles etc. are all unisexual organisms. Humans are unisexual organisms. Some of the humans are males whereas other humans are females. The male humans have only male reproductive organs called ‘testes’ in the body. And the female humans have only female reproductive organs called ‘ovaries’ in their body. The testes produce the male sex hormone called testosterone, and the ovaries produce two female sex hormones, estrogen and progesterone. The sex hormones play an important role in the process of reproduction. The various functions of the sex hormones are :- (a) The sex hormones control the production of gametes like sperms and ova. (b) The sex hormones maintain the structure and functions of accessory sex organs. The testes and ovaries are the primary sex organs, all other organs associated with the process of reproduction (like penis, seminal vesicles, vagina, uterus and fallopian tubes, etc) are accessory sex organs. (c) The sex hormones develop the secondary sex characteristics. For example, in male the sex hormones develop secondary sex characteristics such as : low pitch voice, growth of hair on chest and in the armpit, growth of moustache and beard, growth of pubic hair and development of Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) muscles. In females, the sex hormones develop the secondary sex characteristics such as : high pitch voice, growth of hair in armpits, growth of pubic hair and development of mammary glands. The sexual reproduction in animals takes place in the following steps: (i) The male parent produces male gametes called sperms. The sperm is a small cell with a long tail (flagellum) for movement. (ii) The female parent produces female gametes called ova. The ovum is a much bigger cell than the sperm, have a lot of cytoplasm. (iii) The sperm enters into the ovum and fuses with it to form a new cell called ‘zygote’. This process is called fertilization. So, the zygote is a ferilized ovum. (iv) The zygote then divides again and again to form a large number of cells. And ultimately zygote grows and develops to become a new baby. The reproduction systems in human beings become functional at a definite age called puberty. The age at which the sex hormones begin to be produced and the boy and girl become sexually mature is called puberty. Puberty tends to start earlier in females than in males. Generally boys attain puberty at the age of 13 or 14 years while girls reach puberty at a comparatively lower age of 10 or 12 years. Sexual Reproduction in Plants: For the male gamete to be able to combine with the female gamete, it is necessary that first the pollen grains from the anther of stamen should be carried to the stigma of carpel. The transfer of pollen grains from the anther of a stamen to the stigma of a carpel is called pollination. Hence, pollination is said to take place when pollen grains are carried from anther to the stigma of the flower. Pollination is done by insects like bees and butterflies, birds, wind and water. The transfer of pollen from the anther of one flower to the stigma of another flower of the same or of a different plant is called cross pollination. The sexual reproduction in plants takes place in the following steps: (i) The male organ of flower called 'stamen' makes the male gametes (sex cells) of the plant. These male sex cells are present in pollen grains. (ii) The female organ of a flower called 'carpel' (or pistil) makes the female gametes (female sex cells) of the plant. These female sex cells are present in ovules. (iii) The male gametes present in pollen grains fertilise the female gametes present in ovules. (iv) The fertilised ovules grow and become seeds. (v) The seeds produce new plants under suitable conditions. Human Eye The main parts of the human eye are : cornea (C), iris (I), pupil (P), ciliary muscles (M), convex lens (called eye lens) (L), retina (R) and optic nerve (N). The front part of the eye is called cornea. It is made of a transparent substance and it is bulging outwards. The light coming from objects enters the eye through Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) cornea. Just behind the cornea is the iris. There is a hole in the middle of the iris which is called pupil of the eye. Thus, pupil is a hole in the middle of the iris. The pupil appears black because no light is reflected from it. The eye-lens is a convex lens made of a transparent and flexible material like a jelly made of proteins. The eye-lens is held in position by ciliary muscles. The focal length of eye-lens (and hence its converging power) can be changed by the action of ciliary muscles. The screen on which the image is formed in the eye is called retina. The retina is behind the eye lens and at the back part of the eye. The retina of an eye is just like the film in a camera. The retina is a delicate membrane having a large number of light sensitive cells called ‘rods’ and ‘cones’ which respond to the ‘intensity of light’ and ‘colour of objects’ respectively, by generating electrical signals. The eye-lid in front of the eye works just like the shutter in a camera. When eye-lid is open, light can enter the eye but when eye-lid is closed, no light enters the eye. The space between cornea and eye-lens is filled with a viscous liquid called ‘aqueous humour’. And, the space between eye-lens and retina is filled with another liquid called ‘vitreous humour’. The image formed on the retina is conveyed to the brain by the optic nerve and gives rise to the sensation of vision. When the image falls on the retina then these light-sensitive cells get activated and generate electrical signals. The retina sends these electrical signals to the brain through the optic nerve and gives rise to the sensation of vision. Although the image formed on the retina is inverted, our mind interprets the image as that of an erect object. A small region of the retina where the optic nerve enters the eye- ball, is insensitive to light and it is called blind spot. The eye-lens forms a real image of the objects on the retina of the eye and we are able to see the objects. Myopia (or short-sightedness) is that defect of the eye due to which an eye cannot see the distant objects clearly, though it can see the nearby objects clearly. The defect of eye called myopia (or short- sightedness) is caused : (i) due to the high converging power of the eye-lens, or (ii) due to the eye ball being too long. As a result, the image of a distant object is formed in front of the retina in a myopic eye. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Myopia or short-sightedness is corrected by using spectacles containing concave lenses. When a concave lens L of suitable power is placed in front of the eye as shown in Figure then the parallel rays coming from distant object (at infinity) are first diverged by concave lens and then converged by the eye-lens and helps in forming the image of the distant object on the retina. Hypermetropia (or long-sightedness) is that defect of the eye due to which an eye cannot see the near objects clearly, though it can see the distant objects clearly. A person with this defect has the ‘near-point’ farther away from the normal near point (25 cm). Such a person has to keep reading material much beyond 25 cm from the eye for comfortable reading. The defect of eye called hypermetropia (or long-sightedness) is caused : (i) due to the low converging power of the eye-lens, or (ii) due to the eye ball being too short. As a result, the image of a near object is formed behind the retina. Hypermetropia or long-sightedness is corrected by using spectacles containing convex lenses. When a convex lens L of suitable power is placed in front of the eye as shown in Figure then the parallel rays coming from near object are first converged by convex lens and then diverged by the eye-lens and helps in forming the image of the distant object on the retina. Presbyopia is that defect of vision due to which an old person cannot see the nearby objects Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) clearly due to loss of power of accommodation of the eye. For example, an old person having presbyopia cannot read a book or newspaper comfortably and clearly without spectacles. Presbyopia occurs in old age due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye-lens. The near-point of the old person having presbyopia gradually recedes and becomes much more than 25 centimetres away. Presbyopia is corrected by using spectacles having convex lenses. Astigmatism : In this case a person cannot see horizontal objects or vertical objects. It can be remedied by using cylindrical lenses. Colour Blindness : When a person is unable to distinguish between colours especially red and green, he is colour blind. Colour blindness is caused by the deficiency of Vitamin ‘A’. It is a hereditary disease. Sons of a colour blind persons are likely to be colour blind because sexual inheritance finds easy way in case of males but not necessarily in case of females. Night Blindness : It is also a hereditary disease and is caused by deficiency of Vitamin A. A persons suffering from night blindness cannot see objects clearly at night. The eye can see the nearby objects because the eye-lens can become 'more convex' due to its power of accommodation. The maximum "accommodation" of a normal eye is reached when the object is at a distance of about 25 cm from the eye. After this the ciliary muscles cannot make the eye-lens bulge more. So, an object placed at a distance of less than 25 cm cannot be seen clearly by a normal eye because all the power of accommodation of the eye has already been exhausted. Skeletal System: The frame of human body is made up of bones. It consists of 206 bones. An infant has almost 300 bones. The longest bone is femur or thigh bone and the smallest stapes (in the middle ear). It helps the body to stand, give shape to the body and also protects the inner organs like brain, heart etc. It also gives attachment to muscles. In the bone marrow RBCs are produced. Muscular System: comprises the flesh pieces under the skin. There are two types of muscles (i) Voluntary Muscles which we can control and (ii) Involuntary muscles over which we have no control, e.g., cardiac muscles. Proteins : help to build up tissues of the body and repair of worn out tissues. They are found in eggs, meant, flour, rice, milk and more importantly in Cheese and Soya beans. Fats : help in burning carbohydrates and work as reserve food. Found in butter, ghee, vegetable oils etc. Carbohydrates : supply instant energy to the body. Found in potatoes, rice, wheat and sugar. Minerals : Mineral Salts are salts of iron, calcium and sodium. Salts of iron enrich the blood. Iron is found in green vegetables, apple, banana, etc. Salts of calcium help in formation of bones and teeth. Calcium is found in eggs and milk. Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) Vitamins Vitamin A : is found in milk, butter, Ghee, Carrot, tomatoes, green vegetables and cod liver oil. Its deficiency causes anemia, night blindness, colour blindness and rickets. Vitamin B : is found in seeds of fruits, plants and yolk of egg. It helps in the growth, appetite and nervous system. Its lack causes enlargement of liver and beri-beri. Vitamin C : is found in juicy fruits like oranges, lemons, tomato, cabbage, onions and green vegetables. It lack causes defective bones and teeth and scurvy. Vitamin D : is found in milk, butter, cod liver oil and most importantly sun rays. Its lack causes rickets. Vitamin E : is found in wheat, corn, green vegetables, etc. Its lack causes sterility. Human Diseases Viral Diseases : Rabies or Hydrophobia is caused by rabies virus. Its mode of transmission is bite of animals like mad dog, monkey, etc. Small Pox : is caused by variola virus. Spreads by direct contact and also indirectly by injected articles. Chicken Pox is caused by varisela virus. It is transmitted in the same way as small pox. Dengue fever bite of aedes mosquito. Polio spread by housefly and contaminated water. AIDS is caused by HIV virus. Its mode of transmission are :- (i) blood transfusion (ii) Intravenous Drug Use (iii) Unsafe Sex Hepatitis is caused by hepatitis virus. Mode of transmission is same as AIDS. Bacterial Diseases Diphtheria, Pneumonia, Tuberculosis, Plague Malaria is caused by bite of infected female anopheles mosquito. S. No. Name of the Disease Body part it affects 1. Cataract Eye 2. Diphtheria Throat 3. Jaundice Liver 4. Pneumonia Lungs 5. TB Lungs, Intestine and Bones 6. Trachoma Eyes 7. Diabetes Pancreas 8. Pyorrhea Gums and Teeth 9. Meningitis Spinal chord and Brain 10. Arthritis Bones and Joints Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exams – Join Today Happy Institute C-6/36, Keshav Puram, Delhi – 35 (8586020110) 11. Conjunctivitis Eyes 12. AIDS Immunity System 13. Hepatitis Liver Delhi’s No.1 Result Oriented Coaching Institute For SSC CGL/HSL, Bank PO/Clerks, SO-PS Exam (UPSC), Shorthand (Speed & Theory) & Other Competitive Exa

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