Elements and compounds Tnpsc notes

Elements and Compounds in Chemistry

Types of Pure Substances

For a normal person, a pure substance means it is free from adulteration.

Even Milk, Air, Water, etc., are not pure.

In some cases, there are pure substances or single substances such as distilled water, sugar, baking soda, etc. Also, copper used for making electric wire is a pure substance.

How to recognise a pure substance?

One can identify a pure substance by its characteristics, such as viscosity, refractive index, electrical conductivity, melting point, and density.

A pure substance is defined as a substance that has a fixed composition and fixed properties that cannot be taken away by physical methods. For Pure water freezer at 0° Degree Celsius and boiling at 100° Celsius at one atmospheric pressure.

This nature of water same, irrespective of its origin. The Pure Water that is H₂O has two Hydrogen atoms and one oxygen atom. This composition cannot be changed by physical methods. A pure substance is either an element (Copper) or a compound (Calcium Carbonate).

Element

“An Element is a pure substance that cannot be split into anything simple by physical or chemical methods. –Boyle

“An Element is the basic form of matter that cannot be broken into a simpler substance” – Lavoisier

“An Element is made of the same kind of atom” – Modern Atomic Theory

Examples of elements are Oxygen, Carbon, Iron, Copper, etc. In Oxygen, it has only Oxygen atoms. Similarly, Carbon has only a Carbon atom.

Therefore we can conclude that all the elements are made of one kind of atom only. The atoms of different elements are not similar.

For example, if atoms of Gold and Platinum are compared, we find that there is a difference in their internal structure and size between them. There are 118 found up to date. Out of it, 92 elements occur naturally and 26 element elements are manmade.

But only 112 elements are recognized and allotted symbols by IUPAC (International Union of Pure and Applied Chemistry). There is an abundance of elements in the earth’s crust either in the combined or free state.

Oxygen is more abundant in the earth’s crust followed by silicon. Oxygen and silicon make up three-quarters of the earth’s crust.

Element present in the earth crust — Fig: Elements present in the earth crust

99% of the mass of the human body is made of six elements such as oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus, and the rest other elements.

Elements present in the human body — Fig 2: Elements present in the Human body

Almost all the plants and animals are made of a few elements only.

They are Oxygen at 65%, Nitrogen at 3%, Calcium at 2%, and Carbon at 18% along with some other elements. Hydrogen and Helium are the primary elements of the Sun, Stars, and Universe.

Classification of elements by Physical Properties

The elements can be classified based on the state of the subdivision as Solids, Liquids, and Gases.

Liquid elements are Mercury, Bromine (at room temperature) and Cesium, gallium at (30° C).

Gaseous elements are Hydrogen, Nitrogen, Oxygen, Chlorine, fluorine, Helium, Neon, Argon Krypton, Radon, and Xenon. Solid elements are Carbon, Silicon, Iron, Gold, etc.

Classification of Elements by Properties

Elements can be classified by their properties into Metal, Non-Metals, and Metalloids.

Metals – 70 elements out of 92 elements are metals.

Metals are characterized by:

Hardness, Shining in appearance (Lustrous).
Malleability (can be beaten to thin sheets).
Ductility (can be drawn to long wire)
Metals are the finest conductors of electricity and heat.
Example of Metals is Copper, Silver, Gold, etc.

Non-Metal are characterized by:

Only 16 to 17 elements are non-metals.
There are soft and non-Lustrous (non-shining)
Non-Metals are Non-Malleable (cannot be beaten into thin sheets).
Non-Metals are Non-Ductile ( Cannot be drawn into a thin wire)
Non-Metals are very bad conductors of heat and electricity.
Example of Non-Metals is Hydrogen, Oxygen, Sulphur, Carbon etc.

Metalloids are elements that have the property of both metals and non-metals. There are very few metalloids. Examples of Metalloids areBoron, Silicon, Germanium, etc.

Why are Symbols used to represent Chemistry?

It is for Convenience. Every chemical change can be easily represented in the form of a chemical equation. It is difficult to represent the chemical reaction with the full name. So there is a need for the symbol to represent the elements in Chemistry.

What is a Symbol in Chemistry?

A symbol is a short form of the name such as the UK for the United Kingdom, the United States of America as the USA, etc.

In Chemistry, symbols are used to represent the names of elements. The Greece, some earliest symbols are of the form of geometrical shapes used to represent the elements such as Earth, Fire, Air, and Water.

In the time of the Alchemist, the different element was represented using Pictorial symbols.

phosphorus alchemical symbol — Phosphorus alchemical symbol

The work of trying to change less valuable metal into gold was called Alchemy. The people who do this work are called Alchemists. John Dalton, an English Scientist 1808 tried to use a pictorial representation of the element.

Dalton symbols were difficult to draw and it was inconvenient, hence Dalton symbol was not used.

Jon Jakob Berzelius, a Swedish Chemist 1813, devised a system of using the letter of the alphabet as symbols.

Dalton System of Determining Symbols of the Elements

Most elements, mainly non-metals, use the first letter of their name.

Dalton systems - elements and its symbols — Dalton Systems- Elements and their symbols

If the elements have the same initial letter as another, then the second letter is taken as its symbol.

Dalton System - Element Symbols with Two Letter — Dalton System – Element Symbols with Two Letter

If the first two letters of the names of elements are the same, then the first and second or third letter is taken so that the two symbols are not common.

Dalton System - When first two letter are same then third letter is taken — Dalton System – When the first two letters are the same then the third letter is taken

Some symbols are made from the old names or Latin names.

Dalton System - Symbol based on old element name and Latin name — Dalton System – Symbol based on the old element name and Latin name

Some elements are named after Country, Scientist, Color, mythological Character, and planets.

Element symbols based on Country, Scientist, Color, Planets etc — Element symbols based on Country, Scientist, Color, Planets, etc

How to write a symbol?

A single letter as a symbol should be written in Capital. Two letters as a symbol, the first letter should be capitalised and the second letter should be small. Importance of the Symbol of an element

The symbol of an element symbolizes:

Element Name
One atom of the element
For Example, the O symbol stands for the element of Oxygen and One atom of Oxygen.

Molecule of Element

A Molecule of an Element contains two or more similar atoms. For example, a Chlorine Molecule has two atoms of Chlorine and it is shown as Cl₂(Chlorine).

And Nitrogen (N₂₎ has two atoms of Nitrogen. Chlorine, Nitrogen, etc have two atoms of the same kind called Diatomic Molecules.

Ozone (O₃₎ consists of three same atoms. Phosphorus (P₄) consists of 4 same atoms. Sulphur (S₈) has consisted of 8 same atoms.

What is a Compound?

Compound - Combination of Elements — Compound – Combination of Elements

There are less than 120 elements and unlimited compounds. Common compounds are Table Salt, Water, Sugar, Sand, etc. The bodies of plants, animals, humans, etc are made of hundreds of compounds.

Compounds are formed when two or more elements join together in a fixed ratio by mass.

For example, water (H₂O) is formed by a combination of Hydrogen and Oxygen in the ratio of 2:1 by volume or 1:8 by mass.

Element + Element –> Compound

N₂+ 3H₂–>2NH₃

2H₂ + O₂ –> 2H₂O

Sulphur with oxygen forms colourless gas called Sulphur Di Oxide. Sulphur di Oxide gives a pungent smell when heated.

S + O₂–> SO₂

The greyish liquid formed when Iodine, Aluminium are mixed with water. This compound is called Aluminium Oxide.

2Al + 3I₂–> 2 AlI₃

The mixture of Iron powder and Sulphur is heated in a test tube. Due to heating, a grey brittle compound is formed which is called Iron Sulphide.

Fe + S –> FeS

Characteristics of a Compound

A chemical compound is formed by Chemical, the reaction between two or more elements in a fixed ratio by mass. Every individual element cannot be separated from the compound by physical methods.

A compound is formed when two or more join as a compound associated with the release or absorption of heat. Properties of the elements and the compound formed out of the same elements are different.

A compound is homogenous, and one cannot see the individual element in a compound. The compound is entirely a new thing formed.

Classification of Compound

Inorganic compounds

Those obtained from non-living things such as Rocks, Sand, and Minerals are called Inorganic compounds. An example is Chalk, Marble, Baking Soda, etc.

Organic compounds

The compound is obtained from living sources such as Plants, animals, bacteria, fungi, etc. Examples of organic compounds are proteins, Waxes, Oil, and Carbohydrates.

Uses of Compounds

Common Name	Chemical Name	Components	Uses
Water	Hydrogen Oxide	Hydrogen and Oxygen	Universal Solvent and life source as drinking compound for life on planet earth
Table Salt	Sodium Chloride	Sodium and Chlorine	Provides taste for food, prevent dehydration, preservative of vegetable and non-vegetables
Sugar	Sucrose	Carbon, Hydrogen, Oxygen	Provides sweetness to food. Also used as a preservative. Eg: Sweets, toffee, fruit juices
Baking Soda	Sodium Bi Carbonate	Sodium, Hydrogen, Carbon, and Oxygen	Used in Fire extinguisher, baking powder preparation. Used in Cake and Bread preparation
Washing Soda	Sodium Carbonate	Sodium, Carbon, and Oxygen	Cleaning agents such as making of Soaps and Softening of hard water
Bleaching Powder	Calcium Oxy Chloride	Calcium, Oxygen, and Chlorine	Used as Bleaching agent, disinfectant, and sterilization of drinking water
Quick Lime	calcium oxide	calcium and oxygen	used in the production of glass and cement
Slaked Lime	Calcium Hydroxide	calcium, Hydrogen, and oxygen	Whitewashing of walls
Lime Stone	Calcium Carbonate	Calcium, Carbon, and Oxygen	Making of Chalk pieces

Table of Compound, its chemical name and its uses

Molecule of Compound

The molecule of a compound is one that has two or more different types of atoms.

For example, the molecule of hydrogen chloride contains one atom of hydrogen and one atom of chlorine. Also, Water contains one atom of oxygen and two atoms of hydrogen.

What is a Formula?

A molecule of an element or a compound is represented through a formula. The formula speaks for the number of atoms of each element in the molecule.

Example H₂represents one mole of hydrogen formed by two atoms of hydrogen fused together.

For Water, that is H₂O that represents two atoms of hydrogen chemically fused with one atom of oxygen. Note: In H₂O, only two atoms of hydrogen are shown, 1 atom of oxygen is not shown. We can conclude that if there is no number as a Subscript, we remember that it is one atom.

What is Valency?

Valency is the ability of an element to combine with others. Oxygen is more likely to combine with Hydrogen than chlorine. Just like some people are friendly with some limited people.

The Hydrogen valency is taken as standard, and other elements’ valency is expressed in terms of hydrogen. The hydrogen atom’s valency is taken as one.

As most of the elements do not merge with hydrogen, the valency of an element is also defined in terms of chlorine or oxygen.

Valency concerning Chlorine

As the valency of chlorine is one, the number of chlorine atoms with which one atom of an element can combine is called its valency.

Valency concerning Oxygen

The valency of oxygen is 2. Double the number of oxygen atoms with which one atom of an element can combine is also called valency. Some element shows more than one valency and is called valence elements.

For example Valency of Iron in FeCl₂is 2. The valency of Iron in FeCl₃is 3. Some elements, mostly rare gases like helium and neon do not merge with other elements and are called Zero Valency.

Some important things in Elements and Compounds

The Air we breathe is not a pure gas it is a mixture of substances. Milk is a liquid mixture of proteins, water, and fat.

“Atom is the smallest particle of an element”.

A molecule is made of the same kind of atoms or different kinds of atoms. Amazon forest produces 20% of the world’s total oxygen. One Once of Gold can be drawn into a thin wire of length of 80km or 50 miles.

The carbon in the human body is enough to fill 9000 lead pencils. The noble gas Xenon lasers can cut things even though diamond-tipped blades cannot cut. The human body contains an average of 250grams of salt.

The metal that has the highest melting point is Tungsten which has 3410° C.

Elements and Compounds – Tnpsc General Studies Pdf

Acids, Bases and Salts Tnpsc

Construction and working of Laser Tnpsc

Laser

This article is compiled for the topic “ Laser” in General Studies Tnpsc. This note is compiled from Samacheer Kalvi Book.

This note is for revision only. Kindly refer to the Original Samacheer Kalvi book for more clarity.

Laser meaning or laser full form is light amplification by the stimulated emission of radiation. The difference between laser light and ordinary light is the ordinary light emitted from a normal light source is unclear or disordered or technically called Incoherent.

Ordinary light is incoherent because different atom emits different radiation of light at different stages. For the interference of light, coherent (consistent or clear) light is essential. Also, two different sources, cannot give coherent light.

For research needs, two independent coherent light from a single source is obtained. For this, a light technology called LASER is developed to provide highly coherent light.

Fig:1 a) Ordinary Light Source b) Monochromatic Source c) Laser Source

Characteristics of Laser

The laser beam of light is monochromatic.

The laser beam is clear or coherent.

The laser beam is exactly the same phase with each other.

The laser beam does not bend or diverge.

The laser light is extremely strong and intense.

Working of Laser and principle

Spontaneous and Stimulated Emission

An atom goes through a transition ( change from one state to another) between two energy E₁and E₂. It emits or absorbs a photon of some energy E₁– E₂= hv.

In a system of thermal equilibrium, the atoms in the ground state (N₁) is greater than the atoms in the excited state (N₂). Let the Groud state be E₁and the excited state is E₂.

Stimulated Absorption

When Photons having energy E1 – E2 = hv falls on the system the thermal equilibrium, the photon makes the atom in the ground move to the excited state. This phenomenon is called induced or stimulated absorption.

Fig:2 – Stimulated or Induced Absorption

The action that makes the atoms in the ground state to move to the excited state is called pumping.

When Pumping happens due to external energy or force, the atoms in the excited state are increased such that the atoms in the excited state are greater in number than in the ground state. This phenomenon is called Population Inversion.

The life of atoms that stays excited (excited state) is usually for 10^-8seconds. The exited energy levels with atom lifetime greater than 10-3 seconds and such energy levels are called the Metastable states.

When the excited energy level becomes normal, the atom in the excited state returns to the ground energy state without any external agency. During the transition stage, a photon of energy E₁– E₂= hv is emitted and is called Spontaneous Emission.

The atom stays some time at these energy levels if the excited state is metastable (atom lifetime greater than 10^-3seconds).

By using the Photons of energy hv = E₂– E_1,the atom from the metastable state can be brought down to lower energy levels. A Photon of energy hv = E₂– E₁is emitted which brings atoms from the metastable state to lower energy levels. This is called Stimulated Emission or Induced Emission.

“A photon produced by stimulated emission is called secondary photon (or) stimulated photon.”

The secondary photon is usually in phase with the stimulating photon. These photons, in turn, stimulate the emission further and the process continues to produce a chain – reaction which is called Laser action by this reaction, all the emitted photons that have similar energy and frequency are in phase with each other.

Thereby, a highly monochromatic, perfectly coherent, strong radiation is produced in a laser beam.

Condition for Laser Action

The system must have an inverted population, that is fewer atoms in the ground state than the excited state or Excited-state must have more atoms than the ground state. The should be a metastable state.

The emitted photons must stimulate further to create more radiation for this reflecting mirrors are placed at the ends of the system.

Types of Laser

Application of Laser

As the laser is highly monochromatic it is used for a variety of scientific and industrial applications as well as in research.

Industrial Uses

It is used for drilling fine holes in diamonds, hard surfaces, hard sheets etc.

It is used for cutting thick hard metals.

It is used for welding.

In the manufacturing of semiconductors, chip, electronic circuits, etc it is used to vapourize the unwanted materials.

Also used to determine the quality of the materials

Medical Uses

In hospitals, the laser is used to microsurgeries due to its narrow angular spread of the beam.

It is used to treat kidney stone, tumour.

It is used in Cutting and sealing of blood vessels in brain surgery and retina detachment.

It is used in endoscopy.

It is used to treat cancer in humans and animals.

Scientific, Engineering and Defence Uses

It is used to transmit large messages at a time in radio, television, and telephone as the laser has a single frequency.

It is used in optical communication as it uses semiconductor laser is used as the light source.

Due to its angular spread, it is used in microwave communication, satellite communication, and rockets.

The laser used finding and locking the target in defence.

The distance between the earth and other planets, natural satellites can measure using lasers.

It is used in the Radar, to accurately determine the distance, speed and direction of the object, and also size and form of the targets.

Maser

Maser working is almost the same as the working of Laser.

When the emitted photon is of microwave frequencies.

In Maser, Material used is Paramagnetic ions.

The Maser material is usually Chromium, Gadolinium ions doped as impurities in ionic crystals.

Another Maser material is Ammonia Gas.

Maser is used for analysis in Molecular spectroscopy.

Laser – Tnpsc General Studies Notes Download

Sound Tnpsc Notes

This article is written for the Tnpsc exam for the topic ‘Sound’, in General studies. Science part (Physics).

This note is for quick revision purposes only, Kindly refer to Samacheer Kalvi Book.

What is sound in physics?

Sound is a type of energy that creates a sensation in our ears. Sound in physics is the vibration of objects or substances. These vibrations travel as a form of disturbances or waves using a medium such as air, water, railway track etc. and reach our ear as sound.

Not all the sounds humans can hear. Humans can sound of certain ranges. Not all sound is as pleasant as music. Some sounds are noises that are unpleasant to hear.

Production

Production of Sound can be observed everywhere, some practical examples of sound production in the lab using Tuning Fork. Tuning Fork produces sound when vibrates. Tumbler with water, when hit by spoon, produces sound also vibration in water is noticed.

Here mechanical energy vibrates the objects and vibration creates the sound. This is because the vibration is one that creates a sensation of sound. The Vibration is nothing but “To and Fro Movement”.

Propagation of Sound Waves

The sound needs a medium to propagate. Example of Medium is Air, water, Thread, Railway Track etc. The sound cannot travel in Vaccum.

This can be observed in the Lab using Electric Bell inside the vacuum jar. As no sound is heard after air is fully removed from the Jar.

Sound moves from one to another point through a medium. When the source of the sound such as an object vibrates, it also vibrates the particles of the medium. This in turn vibrates the other particles near to it. So that each particle vibrates the particles nearby and a wave is created.

As a result, sound vibration travels to the other end. A point to note is, only the vibration move through the medium, not the particle. The particle changes its position and comes back to its original position. All the particles move in “to and fro motion”.

In the wave there are two parts, they are compression and rarefactions. The wave that propagates with compression and rarefactions are known to be Longitudinal waves.

The Longitudinal waves the particles of the medium move “to and fro” in the direction of propagation of the wave.

The sounds are longitudinal.

Compression is an area where the particles of the medium crowded together. Rarefaction is an area where the particles are spread or particle density is low.

Figure 1: Sound is the Longitudinal

Sound Tnpsc Notes Pdf Download

Nuclear physics basics and Nuclear technology Upsc

Basics of Nuclear Science

Here’s a table summarizing the basics of nuclear physics, covering important concepts, terms, and their significance:

Concept/Term	Explanation	Significance
Nucleus	The central core of an atom, made up of protons and neutrons.	The nucleus contains most of the atom’s mass and is responsible for its nuclear properties.
Proton	A positively charged particle found in the nucleus.	Protons determine the atomic number of an element and its chemical properties.
Neutron	A neutrally charged particle found in the nucleus.	Neutrons help stabilize the nucleus and contribute to atomic mass.
Electron	A negatively charged particle orbiting the nucleus.	Electrons are responsible for chemical bonding and the formation of molecules.
Atomic Number (Z)	The number of protons in an atom’s nucleus.	Determines the identity of an element and its position on the periodic table.
Mass Number (A)	The total number of protons and neutrons in an atom’s nucleus.	Helps in determining the isotope of an element and its nuclear stability.
Isotopes	Atoms of the same element with different numbers of neutrons.	Isotopes of an element have the same chemical properties but may differ in stability and mass.
Radioactive Decay	The process by which an unstable atomic nucleus loses energy by emitting radiation.	Leads to the transformation of a parent isotope into a stable daughter isotope.
Alpha Decay	A type of radioactive decay where an alpha particle (2 protons and 2 neutrons) is emitted.	Alpha particles can be stopped by paper or skin, but are dangerous if ingested or inhaled.
Beta Decay	A type of radioactive decay in which a neutron decays into a proton, emitting an electron (beta particle).	Results in the transformation of a neutron into a proton, altering the atomic number of the element.
Gamma Radiation	High-energy electromagnetic radiation emitted from the nucleus.	Gamma rays are highly penetrating and require thick shielding like lead or concrete to block them.
Fission	The process of splitting a heavy nucleus (like uranium-235) into two lighter nuclei, releasing energy.	Used in nuclear power plants and atomic bombs to generate energy.
Fusion	The process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.	Powers stars, including our Sun, and is the basis for hydrogen bombs and potential clean energy sources.
Binding Energy	The energy required to split a nucleus into its constituent protons and neutrons.	A measure of nuclear stability; higher binding energy indicates a more stable nucleus.
Half-life	The time required for half of a sample of a radioactive substance to decay.	Provides a measure of the rate of decay of a radioactive isotope.
Nuclear Reactor	A device used to initiate and control nuclear fission to produce energy.	Key in generating nuclear power for electricity, with controlled fission reactions.
Chain Reaction	A self-sustaining series of reactions, where products from one reaction trigger further reactions.	Central to both nuclear power generation and nuclear weapons.
Neutron Moderation	The process of slowing down neutrons to increase the likelihood of fission.	Essential in maintaining a controlled nuclear chain reaction in reactors.
Critical Mass	The minimum amount of fissile material required to sustain a nuclear chain reaction.	Determines whether a nuclear reaction will continue or cease.
Nuclear Cross Section	A measure of the probability of a nuclear interaction (like fission or scattering) occurring.	Important in nuclear reaction rates, particularly for reactors and particle accelerators.
Nuclear Fusion Reactor	A type of reactor designed to create controlled fusion reactions, similar to the process in stars.	A future potential source of nearly limitless and clean energy, still in experimental stages.

This table summarizes some of the fundamental concepts in nuclear physics and their importance in both understanding the structure of matter and in practical applications like energy production and medical treatments.

Applications of nuclear technology

Application	Use	Significance
Nuclear Power Generation	Using controlled nuclear fission reactions to produce electricity.	Provides a significant source of low-carbon energy, reducing reliance on fossil fuels for power.
Medical Imaging (Radiology)	Using radioactive isotopes in diagnostic imaging (e.g., PET, MRI, CT scans).	Allows for non-invasive imaging of internal body structures and organs, aiding in diagnosis and treatment planning.
Cancer Treatment (Radiotherapy)	Targeting cancer cells with ionizing radiation to destroy them.	Provides a treatment option for various cancers, improving survival rates and quality of life.
Nuclear Medicine (Radioisotopes)	Using radioisotopes in medical diagnostics and treatment (e.g., iodine-131).	Helps in diagnosing diseases like cancer, heart disease, and thyroid disorders, and treating certain cancers.
Food Irradiation	Exposing food to controlled amounts of radiation to kill bacteria and parasites.	Extends shelf life, reduces spoilage, and makes food safer by eliminating harmful microorganisms.
Carbon Dating (Radiocarbon Dating)	Using the decay of carbon isotopes (C-14) to determine the age of organic materials.	Widely used in archaeology, geology, and paleontology for dating ancient artifacts, fossils, and fossils.
Nuclear Propulsion (Naval Ships)	Using nuclear reactors to power naval ships, submarines, and aircraft carriers.	Provides efficient, long-duration propulsion for naval vessels, reducing the need for refueling.
Industrial Radiography	Using radiation to inspect materials for defects (e.g., welds, pipelines).	Helps in ensuring the integrity and safety of industrial materials, preventing failures and accidents.
Sterilization of Medical Equipment	Using gamma rays or electron beams to sterilize medical instruments.	Ensures that medical tools are free from harmful bacteria, viruses, and other pathogens, improving patient safety.
Nuclear Agriculture	Using radiation to mutate plants or animals for improved yields and resistance to pests.	Enhances food production by creating crops and livestock that are more resilient and productive.
Nuclear Waste Disposal	Safely storing or neutralizing radioactive waste from nuclear reactors.	Prevents environmental contamination and ensures safe management of hazardous nuclear byproducts.
Environmental Monitoring	Using radiation detectors to monitor pollution and radiation levels in the environment.	Helps in tracking radiation levels and ensuring public safety from environmental hazards.
Nuclear Batteries	Using radioisotopes (e.g., plutonium-238) to power small devices (e.g., pacemakers).	Provides long-lasting power for devices that need to function over many years without frequent battery changes.
Neutron Radiography	Using neutron beams to analyze the internal structure of materials.	Non-destructive technique for inspecting materials like metals and composites, widely used in engineering.
Space Exploration (Radioisotope Thermoelectric Generators)	Using nuclear-powered generators to provide electricity for spacecraft.	Enables long-term, reliable power for spacecraft in environments far from the Sun, such as deep space.
Nuclear Forensics	Analyzing nuclear materials to track illicit nuclear activity.	Helps detect and prevent the spread of nuclear weapons and radioactive materials.
Seawater Desalination	Using nuclear energy to power desalination plants for producing fresh water.	Provides an alternative solution to freshwater scarcity, particularly in arid regions.
Nuclear Magnetic Resonance (NMR)	A technique using nuclear magnetic properties to analyze the structure of materials.	Widely used in chemistry, biology, and medicine for analyzing molecular structures, including drug development.
Fusion Energy Research	Investigating nuclear fusion as a future energy source.	Promises a potential source of nearly unlimited, clean energy by replicating the Sun’s energy process.

This table illustrates the wide-ranging applications of nuclear technology across various industries, from healthcare to energy, providing essential tools for improving human life, safety, and sustainability.

Nuclear science and technology

Concept/Technique	Explanation	Application
Nuclear Fission	The process of splitting a heavy atomic nucleus into two lighter nuclei, releasing energy.	Used in nuclear power plants for energy production, and in nuclear weapons.
Nuclear Fusion	The process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.	Researching as a potential source of clean, nearly limitless energy, used in hydrogen bombs.
Isotopes	Atoms of the same element with different numbers of neutrons, leading to different mass numbers.	Used in medicine (e.g., iodine-131 for thyroid treatment), industry (e.g., cobalt-60 for radiography), and research.
Radioactivity	The spontaneous emission of radiation (alpha, beta, gamma) from an unstable nucleus.	Applications in radiotherapy, radiography, and dating methods (carbon dating).
Radioisotopes	A radioactive isotope used in various applications such as medicine, industry, and agriculture.	Used in cancer treatment (e.g., cobalt-60), food sterilization, and radiographic inspection.
Nuclear Reactor	A device used to initiate and control nuclear fission reactions to produce energy.	Used in nuclear power plants to generate electricity and in research reactors for scientific study.
Nuclear Medicine	A medical field using radioactive substances for diagnosis and treatment.	Includes PET scans, cancer treatment, and other diagnostic procedures using radioisotopes.
Neutron Activation Analysis (NAA)	A technique in which materials are exposed to neutrons to identify and quantify elements.	Used in materials analysis, environmental monitoring, and archaeological studies.
Nuclear Magnetic Resonance (NMR)	A technique that uses nuclear magnetic properties to study the structure of molecules.	Widely used in chemistry, biology, and medicine, especially in MRI (Magnetic Resonance Imaging).
Mass Spectrometry	A technique that measures the mass-to-charge ratio of ions to identify and quantify elements.	Used in chemical analysis, detecting isotopic compositions, and studying the composition of materials.
Radiation Protection	Measures and practices designed to protect individuals and the environment from harmful effects of radiation.	Essential in nuclear power plants, medical treatments, and industries using radioactive materials.
Geiger Counter	A device used to detect and measure ionizing radiation.	Used for radiation safety monitoring, environmental assessment, and in nuclear industry settings.
Carbon Dating (Radiocarbon Dating)	A method of dating organic materials by measuring the amount of carbon-14 remaining.	Used in archaeology, geology, and paleontology to determine the age of ancient artifacts and fossils.
Radiotherapy (Cancer Treatment)	The use of radiation to treat cancer by killing or damaging cancer cells.	Common treatment for various cancers, often combined with surgery and chemotherapy.
Thermal Neutron Reactors	A nuclear reactor that primarily uses thermal neutrons to sustain the fission process.	Used in nuclear power generation, research, and isotope production.
Critical Mass	The minimum amount of fissile material required to maintain a self-sustaining nuclear chain reaction.	Important in nuclear weapons and reactors, determining whether a chain reaction will continue.
Fusion Reactors (Tokamak)	A device used in research to create controlled nuclear fusion for energy production.	Ongoing research into clean and sustainable energy sources through fusion.
Radiographic Inspection	Using radiation (gamma, X-rays) to inspect materials for defects or internal structures.	Common in industries like oil, gas, aerospace, and manufacturing to check for material integrity.
Nuclear Waste Management	The collection, transportation, and disposal of radioactive waste materials.	Ensures safe disposal and storage of hazardous materials from nuclear reactors and medical applications.
Plutonium	A radioactive element used as fuel in nuclear reactors and for nuclear weapons.	Used in nuclear reactors for energy production and in the manufacturing of atomic weapons.
Fusion Fuel (Deuterium and Tritium)	Isotopes of hydrogen used in nuclear fusion reactions to release energy.	Potential fuels for future fusion reactors, offering a cleaner and more sustainable energy source.
X-ray Diffraction (XRD)	A technique used to analyze the crystallography of materials using X-ray radiation.	Used in materials science, chemistry, and physics to study the atomic structure of materials.
Gamma Radiation	High-energy electromagnetic radiation emitted from the nucleus of an atom.	Used in medical imaging (e.g., PET scans), sterilization, and industrial radiography.

This table provides an overview of nuclear science and technology, focusing on various concepts, techniques, and their diverse applications across fields like energy, medicine, industry, and research.

Permitted Range of Nuclear Radiation

The permissible range of exposable radiation on Humans is recommended by ICRP (International Commission on Radiological Protection). As per ICRP, radiation is safe is does not affect a person. The safe limit of radiation exposure is 20 Milli Sievert per Year.

In terms of Roentgen, the safety limit is 100mR per Week. If it is 100 R, it may cause a fatal disease like Cancer or Leukemia (Death of red blood corpuscle in the blood). If the person is exposed to radiation of about 600R, it leads to death. The dosimeter is used to detect the levels of exposure to Ionizing radiation.

We use the dosimeter in Nuclear power plants and medical imaging facilities. Pocket Dosimeter provides immediate results to the person exposed to X-Rays and Gamma Rays.

Type of Radiation	Penetrating Power	Shielding Requirements	Applications	Permitted Range in Context

Alpha Radiation

Low (can be stopped by paper or skin)

Paper, clothing, or a few centimeters of air

Used in smoke detectors, radioactive tracers, and some cancer treatments.

Not permitted for direct exposure to the body; harmful if inhaled or ingested.

Beta Radiation

Moderate (can penetrate several millimeters of skin tissue)

Plastic, glass, or a few millimeters of aluminum

Used in medical treatments (e.g., cancer therapy), radiography, and tracers.

Permitted in controlled environments with appropriate shielding to avoid direct skin contact.

Gamma Radiation

High (penetrates deep into tissues and requires heavy shielding)

Lead, concrete, or several meters of air

Used in medical imaging (e.g., PET scans), sterilization, industrial radiography, and nuclear power plants.

Strict limits for exposure; only permitted under controlled conditions with lead or concrete shielding.

Neutron Radiation

High (can penetrate deep into materials and biological tissue)

Concrete, water, or boron-containing materials

Used in nuclear reactors, neutron radiography, and research.

Controlled exposure only; requires thick shielding (e.g., concrete or water) to protect personnel.

X-rays (Similar to Gamma Rays)

Moderate to High (penetrates tissues but less than gamma rays)

Lead or thick concrete walls

Used in medical imaging (X-rays, CT scans), industrial non-destructive testing.

Permitted with radiation protection standards and proper shielding to limit exposure.

Preventive Measures to avoid Nuclear Accidents

We should keep radioactive materials and substances in a thick lead container. While working with Hazardous radioactive materials, lead-coated Aprons should be used.

Should eat in a hazardous environment and while handling nuclear substances.

We should handle radioactive materials only with Tongs or by a remote control device. The workers should wear dosimeters to be aware of the level of radiation.

Preventive Measure	Description	Purpose	Application Area
Regular Safety Inspections	Routine checks on nuclear reactors, equipment, and facilities.	To identify potential faults, wear, and tear before they lead to accidents.	Nuclear power plants, medical facilities with radioactive materials.
Redundancy and Backup Systems	Implementation of multiple safety systems (e.g., backup cooling systems, power supplies).	Ensures continuous operation of safety mechanisms even if primary systems fail.	Power plants, research reactors.
Containment Structures	Strong, reinforced structures designed to contain radiation in case of a reactor failure.	To prevent the release of radioactive materials into the environment.	Nuclear reactors, research facilities.
Emergency Core Cooling Systems (ECCS)	Systems that rapidly cool down the reactor core in the event of overheating.	To prevent a meltdown by removing heat and maintaining core stability.	Nuclear power plants.
Radiation Shielding	Use of materials like lead, concrete, and steel to shield workers and the public from radiation exposure.	To minimize exposure to radiation during reactor operation and emergencies.	Nuclear power plants, hospitals, research labs.
Training and Drills	Regular training for personnel in emergency protocols, safety systems, and crisis management.	Ensures that staff are prepared to handle accidents and emergencies effectively.	Nuclear power plants, medical facilities, research labs.
Automated Control Systems	Use of computerized systems to monitor and control reactor operations, detecting irregularities.	To identify and mitigate risks in real-time, preventing human error.	Nuclear reactors, power plants, research facilities.
Waste Management and Storage	Safe handling, storage, and disposal of radioactive waste materials.	To prevent contamination and environmental hazards from improperly managed nuclear waste.	Nuclear power plants, research facilities.
Independent Safety Oversight	External safety audits and inspections by regulatory bodies (e.g., IAEA).	To provide unbiased safety evaluations and ensure compliance with regulations.	Nuclear power plants, research reactors.
Seismic and Structural Integrity	Designing and reinforcing structures to withstand natural disasters such as earthquakes.	To protect reactors from damage caused by earthquakes or other external forces.	Nuclear power plants, reactors in seismic zones.
Radiation Monitoring Systems	Continuous monitoring of radiation levels in and around nuclear facilities.	To detect any unusual radiation spikes and prevent widespread exposure.	Nuclear power plants, medical facilities, research labs.
Controlled Access to Sensitive Areas	Limiting access to high-radiation areas and ensuring only trained personnel enter.	To protect unauthorized individuals from radiation exposure.	Nuclear reactors, medical facilities.
Early Warning Systems	Automated systems that alert authorities and workers of any potential nuclear hazard.	To allow for timely evacuation, containment, and mitigation efforts.	Nuclear power plants, research reactors.
Pre-emptive Equipment Maintenance	Routine replacement and maintenance of aging equipment (e.g., reactor parts, pressure vessels).	To prevent equipment failure that could lead to accidents.	Nuclear reactors, power plants.
Public Communication Systems	Transparent communication with the public regarding risks and emergency procedures.	To ensure the safety and preparedness of nearby populations in case of an incident.	Nuclear power plants, emergency response teams.
Use of Passive Safety Features	Safety systems that operate without external power or human intervention, relying on physical laws (e.g., gravity, natural convection).	To reduce reliance on active systems and human error in emergencies.	Modern nuclear reactor designs, including Generation IV reactors.
Implementation of International Safety Standards	Adherence to global safety standards such as those set by the International Atomic Energy Agency (IAEA).	To align with best practices and international safety norms.	Nuclear reactors, medical facilities, research labs.
Nuclear Fuel Management	Proper monitoring and control of nuclear fuel during transport, storage, and use.	To prevent fuel-related accidents, including overheating or criticality incidents.	Nuclear reactors, research reactors.
Decommissioning and Site Cleanup	Safe decommissioning of outdated or unsafe reactors and cleaning of contaminated sites.	To prevent long-term environmental harm from outdated or unsafe nuclear facilities.	Decommissioned nuclear plants, former research reactors.

Nuclear Physics Pdf Download

Nature of Universe Tnspc Samacheer notes

The universe is all of space and time and its contents. The universe consists of all of existence, fundamental interaction, physical processes, and all forms of energy and matter and the structures they form, from the sub-atomic particles to entire galaxies.

Three most basic types of Universe are and is concerning three possible shapes, that is a flat universe (Euclidean or zero curvature), a spherical or closed Universe (positive curvature), or a hyperbolic or open Universe (Negative curvature).

This article is written for the Tnpsc and Upsc exams. Points to remember for the topic “Nature of Universe” and “Earth and universe Tnpsc“. This reference material is compiled from the Samacheer Kalvi book. The universe is a vast endless space with galaxies, stars, planets, energies, etc. It is about the universe and the solar system.

Best books for Tnpsc exams/ Upsc

How were the universe and the earth formed?

One of the popular theories was German professor Immanuel Kant, his theory was revised by Laplace in 1796.
According to Immanuel Kant and Laplace, the planets were formed from the cloud of material associated with the youthful sun.
Then, the accretion theory of the earth’s formation by Lyttleton.
- According to Lyttleton, approximately 46 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula.
- This solar nebula began to spin, and the sun formed in the centre of the solar system as a result of gravity collapsing the materials on itself.
- The rest of the material is left out such as hydrogen and helium bound by forces of gravity to form other things such as planets.

Theories of the origin of the universe

The most popular theory for the universe’s origin is the Big Bang Theory, also called the Expanding Universe Hypothesis.
A Belgian astronomer, Georges Lemaitre first to propose the theory of the origin of the universe. Edwin Hubble provided the Evidence that the universe is expanding, called the Big Bang Theory.
- According to the Big Bang Theory, the universe is formed about 13.75 billion years ago.
- Like a rapidly expanding balloon, it swelled from the size of an electron and expanded in all directions with great and continuous growth every second. From this many stars and groups were formed.

Universe, Solar System & Galaxy

Solar system galaxy universe Differences

Solar System	Galaxy	Universe
The Solar System is a system of the Sun and its family. The sun is at the centre and its family of 8 planets revolves around it.	Galaxy – The Solar system is a part of the galaxy. The sun is actually a star with several planets revolving around it. There are several such stars is present in the Galaxy.	Universe – It is the whole space surrounding us. It includes all the galaxies, solar systems, planets, dust, etc.
	The Galaxy in which we live is the Milkyway Galaxy.	Compared to our solar system the universe is very huge and our solar system is part of the universe.
	The galaxy of the milky-way is yet to be revealed, Whether it is a galaxy inside some other galaxy or this galaxy we studied so far is infinite with definite boundaries.

Difference between Galaxy, Solar System and Universe

The Solar system, galaxy, the universe size order:

If we order and arrange the solar system, galaxy, the universe in the order of largest to smallest, it is :

The first is the Universe which is the largest of all, the second is the Galaxy which is smaller than the Universe and larger than the solar system, Solar (Smallest of Universe and Galaxy).

How many solar systems are in the universe?

So far scientists and engineers have discovered 500 solar systems and it keeps adding every year.

Order from smallest to largest galaxy universe solar system

The smallest galaxy is a dwarf galaxy and the largest galaxy is IC 1101.
As already said universe includes everything, there is no such thing as the largest Universe or the smallest universe.
So far we have found 500 solar systems in the universe but we are yet to confirm their sizes.

Galaxy

A Galaxy is a complete unit of stars, stellar remnants, interstellar gas, dust, and dark matter. Our Solar system which we live is part of the Milky way galaxy.

Different Types of Galaxies

Spiral Galaxy – Spiral galaxies consist of a flat and rotating disk of stars, gases, and dust and have a central concentration of stars known as the Bulge. Example of Spiral Galaxies is Milky Way and Andromeda etc.

Elliptical Galaxies – Elliptical Galaxies contain older stars with fewer gases. An example of Elliptical Galaxies is Messier 89.

Irregular Galaxy – Irregular Galaxies are young galaxies with more gases and dust, which makes them very bright. An example of an Irregular Galaxy is the Magellanic Cloud.

The stars, planets, and galaxies only make up 4% of the universe, the 96% cannot be seen or understood. The measurement technique confirmed the age of the universe and the strength of dark energy is called Gravitational Lensing. Dark energy is responsible for the accelerating expansion of the universe.

Stars in the Galaxy and Constellation & its Names

nature of universe - constellation — stars in the galaxy

A star is an astronomical object which has light and heat. The nearest star is the sun to the earth. Sirius is the brightest star than the sun.

Proxima Centauri is the closest star to the sun. The biggest star in the galaxy is UY Scuti. Stars change their forms during their lifetimes such as red giants, white dwarfs, neutron stars, and the black hole.

A constellation is a group of stars that forms a particular shape in the sky. In 1929, the International Astronomical Union (IAU) adopted and defined 88 official constellations.

Astronomer Ptolemy listed 48 constellations in his book Almagest. Ursa Major can be seen in the Northern Hemisphere, a part of the Southern Hemisphere.

Uy Scuti

uy scuti core temperature is 3091.85°C (Approx)

uy scuti vs sun

It is 30 times bigger than the sun and has a 1700 times larger radius than the Sun.

An object travelling at the speed of light will take seven hours to travel along UY Scuti’s great circle but it’s only 14.5 seconds to circle the Sun’s great circle.

uy scuti size is 1.1883 billion km Radius

How many stars are in the Milky Way galaxy?

There are 100 thousand million stars in the Milky Way galaxy.

The Solar System of the Universe

Origin of the solar system

The solar system was formed about 4.5 billion years from a dense cloud of interstellar gas and dust.

The solar system consists of the Sun ( a star) at the centre and the eight planets, moons, asteroids, comets, and meteoroids revolve around it.

The eight namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, revolve around the sun in the fixed path known as orbit.

Solar systems that have more than one star are called Binary star systems. It revolves around the Milky Way galaxy at a rate of 8,28,000 Km/Hr.

It takes 230 million years to complete one revolution around the galactic centre. Solar system size is 287.46 billion km in diameter, taking the sun as the centre.

Kuiper Belt

The Kuiper belt consists of KBO or Kuiper belt objects of a ring of icy bodies, rocks, dwarf planets, comets, etc. It lies past the Neptune orbit.

The inner edge is 30 AU from the Sun. The outer edge is at 1000 AU and some bodies lie beyond 1000 AU. These objects are almost smaller than the dwarf planet “Pluto”.

Beyond the Kuiper belt, there is a giant spherical shell that surrounds our solar system that is the Oort cloud.

Kuiper belt Oort cloud

Oort cloud existence is predicted by mathematical models and observation of comets.

The Oort cloud is made of Icy pieces of space debris, orbiting the Sun at a distance of 1.6 light-years (approx.) away. This shell of material is thick, extending from 5000 to 100,000 AU ( 1 AU = Distance from Sun to Earth or 150 Million Km).

The Oort cloud is the boundary of the Sun’s gravitational boundary. Until now there are 163 known natural satellites in our solar system.

Mercury and Venus have no satellites. But Jupiter and Saturn have the highest number of satellites in our solar system.

How many solar systems in the universe?
As of now(Jan-2021), the scientist have found out 500 solar systems.

The Sun

The Sun is at the centre of the solar system and all the planets revolve around the sun. Sun is a yellow dwarf star, with hot and glowing gases.

The sun’s gravity holds the entire solar system from particles to big planets. The electric current in the Sun generates a magnetic field that is carried by the solar system by the solar wind.

the sun revolves around the centre of the Milky Way galaxy.

The Structure of the Sun

The Sun is made of about 70.6% hydrogen, 27.4% helium, and 2% other gases. The Sun’s enormous mass is held by gravitational forces that produce immense pressure and temperature at its core.

Three main layers in the Sun’s interior are the core, radiative zone, and convective zone. The core in the centre is the hottest zone where nuclear fusion gives the Sun power.

The next zone is the radiative or radiation zone. The energy is carried outward by this layer, which is carried by Photons as thermal radiation. The final layer is the Convection or convective zone, it has the dominant mode of energy flow.

The boundary between the Sun’s interior and the solar atmosphere is called the Photosphere; it is the visible surface of the Sun. The lower region of the solar atmosphere is called the Chromosphere as it appears Bright red during Solar Eclipse.

There is a thin transition region, where the temperature rises sharply, separating the chromosphere from the vast corona above.

The upper corona slowly converted into the solar wind. The solar wind is a flow of plasma that moves outward through our solar system into interstellar space.

The Sun has six regions, the core, radioactive zone, convective zone, photosphere, chromosphere, and corona.

The temperature of the Sun’s surface is about 5,500 to 6000 degrees Celsius. At the core, the temperature is 15 million degrees Celsius which is enough for thermonuclear fission.

In the Sun’s core, hydrogen atoms fuse to create helium.

The Size and Distance of the Sun

The radius of the sun is 695,508 KM. The mass of the Sun is equal to 3,32,946 Earths. The Sun’s volume is equal to 1.3 million Earth.

The Orbit and Rotation

The Milky Way has four main spiral arms, that are Norma & Cygnus arm, Sagittarius, Scutum-Crux, and Perseus. Our Solar system is moving at an average velocity of 828,000 KMPH.

Our Solar system takes 230 million years to make one complete orbit around the Milky Way. The Sun’s axial tilt of 7.25 degrees concerning the plane of the planet’s orbit.

The Sun is not a solid body, so different parts of the Sun rotate at different rates. At the equator, the Sun spins once for about 25 days.

At the poles, the Sun rotates once on its axis every 36 Earth days. The Sun accounts for 99.8% of the mass of the entire solar system.

The Sun’s age is less than half of life and will last another 6.5 billion years before it shrinks down to be a white dwarf. The sun will run out of energy it will become big and engulf the planets.

The Planets

Planet in Greek means Wanderer. The planet is a celestial body that does not have light or heat of its own.

The requirements to be a planet are: It should orbit around the Sun, It should not be the satellite of any planet, It should get a spherical shape due to its mass and self-gravity, and any other celestial body should not cross in its orbit.

The planets are classified into inner planets and outer planets. The inner planets or terrestrial planets or rocky planets are Mercury, Venus, Earth, and Mars are called inner or terrestrial planets.

The outer planets or gaseous planets or giants planets Jupiter, Saturn, Uranus, and Neptune are called outer or gaseous planets.

Each planet spins on its axis, this is called Rotation. One rotation makes one planet day. The planets revolve around the sun in a fixed elliptical orbit called Revolution.

The Mercury

Mercury is nearest to the Sun and it is the smallest planet in the solar system. Mercury does not have any satellites as it is very close to the Sun, the Sun’s gravity is stronger than that of mercury, as a result, the Sun will engulf any closer to Mercury.

It rotates on its axis in 58.65 earth days. It revolves around the Sun in 88 Earth days. The Mercury is at a distance of 0.4 AU away from the Sun.

The light from the Sun takes 3.2 minutes to reach Mercury. Mercury is the second hottest of all planets.

The Venus

Venus is the second planet after Mars. Venus is also called Earth Sister due to its similar size and mass.

Venus is the hottest planet in the solar system, with a surface temperature of 462 degrees Celsius. It is also called “the Morning Star and Evening Star”.

Venus is seen in the east before sunrise and in the west after Sunset. It rotates east to west (clockwise) on its axis. It is one of just two planets that rotate from east to west.

Only Venus and Uranus have backward rotation. It completes one rotation in 243 Earth days; it is the longest duration of any planet. It takes 224.7 Earth days to complete one revolution around the Sun.

The light from the sun takes 6 minutes to reach Venus.

The Earth and its origin

The earth is spherical in shape but it is irregular at the centre often referred to as an ellipsoid.

Earth is the third planet to the Sun and the fifth largest planet. The Earth lies between Venus and Mars. Earth is present in the galaxy named the Milky Way.

Rotation time on its axis: 23 hours 56 minutes and 4 seconds. Revolution around the Sun: 365.25 days The Earth’s surface varies from -88 to 58 degrees Celsius.

Its density is the highest in the solar system. The earth is unique because of the presence of Oxygen, water, and moderate temperature. It is not too close or too distant from the Sun.

It is the only known planet to support life and it is known as a Blue planet due to the presence of water. Moon is the only natural satellite for the planet earth The Sunlight takes about 8.2 minutes to reach the earth.

MACS0647-JD is the farthest known galaxy from the Earth. Planets that are similar to our planet earth are Gliese 667Cc, Kepler-22b, Kepler-69c, Kepler-62f, Kepler-186f, Kepler-452b

The Mars

Mars is the fourth planet to the Sun. It is the 2^nd smallest planet in the Solar system and is also called the Red Planet.

It is reddish due to the presence of iron oxide on its surface. The landmass of Mars and Earth are very similar. It takes 24 hours and 37 minutes to complete one rotation on its axis and it takes 687 days to complete one revolution around the Sun.

The surface temperature of Mars ranges from -153 to 20 degrees Celsius. Apart from Earth, Mars is the most habitable planet.

It has Polar Ice Caps, Volcanoes, Canyons, and weather. The satellites of Mars are Phobos and Deimos

The Jupiter

Jupiter is the largest planet in the solar system. It is the fifth planet from the Sun. It is primarily made of gases and due to this it is called a “Giant Gas Planet”.

It takes 9 hours and 55 minutes to complete one rotation along its axis and it takes 11.86 earth years to complete one revolution around the Sun.

Jupiter has the smallest day in the solar system. Jupiter has a faint ring system around it, they are mostly dust particles.

Moons of Jupiter

The number of moons of Jupiter is 67 confirmed. Galileo Galilei discovered moons of the Jupiter. Ganymede is the largest Satellite of Jupiter and also the solar system. It is also larger than Mercury.

The Moon of Jupiter named after a muse is Aoede. The number of the icy moon of Jupiter is three they are Callisto, Ganymede, and Europa.

Galilean moons of Jupiter are the largest satellites of Jupiter they are Io, Europa, Ganymede, and Callisto. lo, a moon of Jupiter is the third largest of Galilean moons.

The Saturn

Saturn is the sixth planet from the Sun and it is called a Ringed planet. It is the second in size of planet in the Solar System after Jupiter.

Saturn’s rings are beautiful that encircle the planet, these rings are mostly made from chunks of ice and carbonaceous dust. It has 30 rings.

Saturn is the only planet in the solar system, where the average density is less than water. Due to its density which is less than water, this planet may float on water. It has 53 confirmed satellites.

The latest study in 2020, confirmed that Saturn has more satellites than Jupiter. It takes 10 hours and 34 minutes to complete one rotation on its axis.

It takes 29.4 years to complete one revolution around the Sun.

Saturn’s moon Titan

The radius of Titan is about 1,600 miles. It is smaller than earth but it is bigger than earth’s moon and it is the second-largest moon in the solar system.

Titan might support life, 6 billion years from now, this is because it contains rocky Ice at extremely freezing temperatures when the sun becomes a red giant star in the future, the temperature will increase to such an extent that the rocky ice in Titan will become favourable for life similar to earth.

Does Saturn’s moon titan have water?
Titan has ice made of water which is rock hard. It is also believed that there is water ocean below the rock solid ice.

The Uranus

Position from the Sun: 7, Uranus is named after the Greek God of the Sky. Uranus is not visible to the naked eye.

It rotates from east to west and is inclined at an angle of 98 degrees. It is very inclined so that the Sunlight only reaches the polar region.

Hydrogen, helium, and methane are the major gases in the atmosphere. The temperature is very low, as it’s in long distance from the Sun.

Uranus has a dense atmosphere made of Methane, which gives a blue-green appearance. Uranus also has rings. The number of satellites: 27.

The Neptune

Position from the Sun: 8, Rotation time along its axis: 16, Revolution around the Sun: 165 earth years, Number of Satellites: 13, Number of rings: 5

It is the coldest planet in the solar system because of its distance from the Sun. Neptune was first located through mathematical calculations.

The windiest planet is Neptune.

Dwarf Planet

It is a tiny planet in the solar system. A celestial body is called a Dwarf Planet, when it orbits the Sun, weighing for self-gravity and nearly round shape, and it should not be a satellite of any planet.

Examples of Dwarf planets are Ceres, Pluto, Haumea, Makemake, and Eris.

Pluto is officially demoted as the 9^th planet from the Sun.

The Satellites

natural satellite of planets — titan Saturn’s moons

The word Satellite means companion. The only satellite is known as the moon until 1610. Currently, there are 163 known Satellites in the Solar System.

The satellite moves around in the direction of West to East. They do not produce light but it reflects the light of the Sun. The satellites have no water or atmosphere.

The Earths Satellite: Moon

The distance from the Earth is 8,84,401 km. Rotation and Revolution around the earth: 27 Days and 7 Hours and 43 Minutes. The people on earth could see only one side of the moon.

It is the 5^th largest natural satellite in the solar system. The moon was likely to be formed when a Mars-sized object collided with the Planet Earth.

There are high and steep mountains, and many craters on the Moon’s surface. It has 1/6^th gravitational pull of the earth because it is smaller than the earth.

Any object’s weights are 6 times less on Moon than on the earth. The light from the moon reaches the earth in just one and a quarter seconds. Apollo 11 was the first manned mission to land on the Moon, which was sent by Nasa.

Two American astronauts Neil Armstrong and Edwin Aldrin set foot on the moon’s surface on the waterless sea of Tranquility on 20^th July 1969.

They stayed on the moon for 21 hours 38 minutes and 21 seconds, Michael Collins piloted Apollo 11.

Saturn’s Moon: Titan

Titan is the only moon with clouds and an atmosphere. Titan is the largest of Saturn’s moons and the second-largest in the solar system. The first is Jupiter’s moon called Ganymede.

It is the only moon in the solar system with a dense planet-like atmosphere with clouds. Titan is similar to earth’s early years, and earth is warmer because it is closer to the sun.

Titan was discovered by Dutch Astronomer Christiaan Huygens in 1655. Huygens was the manmade object to reach Titan’s surface.

The diameter of Titan is 5150 Km, about half the size of the earth and almost as large as Mars.

The surface temperature is -179 degrees Celsius, which makes water stronger as rocks and allows Methane to be found in its liquid form. Surface pressure is slightly higher than the Earth’s pressure.

The surface pressure of Earth at sea level is 1 millibar while Titan’s is 1.6 millibar. The orbital period is 15,945 days.

Titan’s mass is mainly composed of water in the ice form and rocky material. Titan has no magnetic field.

Asteroids

Asteroids are small rocky bodies that revolve around the Sun. Asteroids are also called Minor planets.

Larger asteroids are called Planetoids, these are found between Mars and Jupiter. This belt is called the Asteroid belt.

The size of asteroids varies from small pebble to 100 km. The asteroids may be fragments of exploded planets in the past or comets.

Comets

The comet meaning derived from the Greek word Aster Komets meaning ‘Long Haired Star’. The comets are made of ice particles and meteoric fragments.

They revolve around the Sun and their orbits are irregular. Sometimes they get very close to the Sun (Perihelion) and far away from the Sun(Aphelion).

The best-known Comet is Halley’s Comet, which appears once every 76 years, it was last seen in 1986 and it will appear again on 28^th July 2061.

Comets are of four types:

periodic comets (e.g. Halley’s Comet), non-periodic comets (e.g. Comet Hale–Bopp), comets with no meaningful orbit (the Great Comet of 1106), lost comets (5D/Brorsen) displayed as either P (periodic), C (non-periodic), X (no orbit), and D (lost).

Meteors

The bright streak of light flashing in the sky at night is called a shooting star. These are removed pieces of rocks mainly from the Asteroid belt. They are called Meteoroids before entering the earth’s atmosphere.

Most of them burnt to ashes while entering the earth’s atmosphere. After entering the atmosphere they are called Meteors.

Some Meteors reach the land or surface, they make craters. These are large enough, as they are not completely burnt into ashes. These are called Meteorites.

An example of a Meteor crater in Northern Arizona and Lake Lonar in the Buldhana District of Maharashtra in India was created by the meteor impact.

Is the universe infinite?

The first thing that comes to our mind when we learn about the Universe is “is the universe infinite or finite“?

The possible answer could be the Universe is very big but finite. This is because we have accepted the Big Bang theory that happened ago 13.8 billion years.

As we live in three-dimensional space, even if light travels in all directions for 13.8 billion years, imagine how much distance it could have covered.

It is seriously huge but it is finite.

Is the universe infinite or expanding?

Yes, as per the Big Bang theory, the universe is still expanding and its size is limited at a certain time point but it is growing every second.

Download Pdf

1.Nature of Universe Tnpsc pdf

2.Nature of Universe in Samacheer Books 11th Standard

Useful Ncert Pdf for Universe and Solar System for Upsc

1.Earth in the Solar System

2.Stars and the Solar System

Power of Reasoning Rote Learning Vs Conceptual Learning Tnpsc

Rote Learning

Rote Learning is something, that a child needs the foundation to be strong needs rote learning.

It is a type of learning, that requires a child or student needs to remember the facts, and knowledge without a need to understand.

It is just like storing data on a memory card. Such learning is referred to as rote learning. Example of rote learning is Multiplication tables, alphabets, numerals, etc.

Rote learning is important to make the student remember certain facts or data, that they should not forget forever.

Conceptual Learning

Conceptual learning, on the other hand, is just the opposite of Rote Learning. Making the students understand the concepts and make them ask why, what, how.

This helps them to use the facts and apply them in their daily life.

Making the student only for rote learning is a dangerous trend, at the end of the day after schooling and graduation, one has to apply the concepts learned in daily life that make the education complete.

The mere memorizing of data in rote learning may help remember for exams but conceptual learning is the one that makes education a valuable asset.

Rote memory and conceptual learning are two different approaches to acquiring and retaining knowledge. They involve distinct cognitive processes and have their own advantages and limitations. Here’s an overview of each:

Rote Memory:

Rote memory refers to the process of learning through repetition and memorization without necessarily understanding the underlying concepts or principles.
It involves memorizing facts, information, or procedures through sheer repetition and drilling.
Rote memorization is often used for learning things like vocabulary words, mathematical formulas, historical dates, or other information that can be easily memorized.
This approach can be useful for quickly recalling specific pieces of information, especially in situations where rapid retrieval of facts is necessary, such as in exams.

Conceptual Learning:

Conceptual learning, on the other hand, focuses on understanding the fundamental concepts, principles, and relationships that underlie a subject or topic.
It involves critical thinking, problem-solving, and the ability to apply knowledge to new and complex situations.
Conceptual learners seek to grasp the “why” and “how” behind the information they are learning, rather than just memorizing isolated facts.
This approach is often used in fields like science, mathematics, philosophy, and critical analysis, where a deep understanding of concepts is essential.

Comparison:

Depth of Understanding: Conceptual learning typically leads to a deeper understanding of a subject because it goes beyond surface-level memorization and encourages critical thinking.
Adaptability: Conceptual learners are often better equipped to apply their knowledge to new and unfamiliar situations, whereas rote memorization may not be as flexible.
Long-term Retention: Conceptual learning tends to result in longer-term retention of knowledge because it is based on understanding rather than simply memorizing, which can be easily forgotten over time.
Contextual Learning: Conceptual learning is more conducive to understanding the broader context and connections between different pieces of information.
Time and Effort: Rote memorization can be quicker for acquiring specific pieces of information, while conceptual learning may require more time and effort.
Subject Matter: The choice between rote memory and conceptual learning may depend on the subject matter. Some topics may require a combination of both approaches.

In practice, a balanced approach is often recommended. Rote memory can be useful for quickly memorizing essential facts and formulas, but it should ideally be complemented by a deeper understanding of the underlying concepts through conceptual learning. The combination of both approaches can enhance learning and problem-solving abilities in various fields of study.

Human Diseases Tnpsc

Disease

A disease is a particular abnormal condition that adversely affects the structure or function of an organism. Diseases can be caused by various factors, including pathogens (like bacteria, viruses, fungi, and protozoa), genetic mutations, environmental factors, and lifestyle choices.

Human Diseases

It is divided into types Congenital and Acquired Diseases.

The Acquired disease is further divided into Communicable and Non- Communicable disease.

Communicable Disease

Communicable diseases, also known as infectious diseases, are illnesses caused by pathogens such as bacteria, viruses, fungi, and parasites. These diseases can be transmitted from one person to another, from animals to humans, or through the environment. They pose significant public health challenges due to their potential to spread rapidly and cause widespread illness.

Pathogen that cause communicable disease:

Bacteria
Virus
Protozoa
Fungi
Helminth

Modes of Transmission of Communicable Diseases

Communicable Diseases: Pathogens, Classifications, and Modes of Transmission

The following table outlines common communicable diseases, their causative pathogens with classification, and modes of transmission:

Disease	Pathogen	Classification	Modes of Transmission
Tuberculosis	Mycobacterium tuberculosis	Bacteria	Airborne (coughing, sneezing)
Malaria	Plasmodium species	Parasite	Vector-borne (Anopheles mosquitoes)
Cholera	Vibrio cholerae	Bacteria	Waterborne (contaminated water/food)
Influenza	Influenza virus	Virus	Airborne, direct contact
Hepatitis B	Hepatitis B virus	Virus	Bloodborne, sexual contact
Dengue	Dengue virus	Virus	Vector-borne (Aedes mosquitoes)
COVID-19	SARS-CoV-2	Virus	Airborne, direct contact
Measles	Measles morbillivirus	Virus	Airborne, direct contact
HIV/AIDS	Human immunodeficiency virus	Virus	Bloodborne, sexual contact, mother-to-child
Typhoid	Salmonella typhi	Bacteria	Waterborne, foodborne
Rabies	Rabies virus	Virus	Animal bites (saliva)
Polio	Poliovirus	Virus	Fecal-oral, contaminated water/food
Tetanus	Clostridium tetani	Bacteria	Contaminated wounds
Leptospirosis	Leptospira species	Bacteria	Waterborne (contaminated water)
Hepatitis A	Hepatitis A virus	Virus	Fecal-oral, contaminated food/water

Non Communicable Diseases

Non-communicable diseases (NCDs), also known as chronic diseases, are medical conditions that are not caused by infectious agents and cannot be transmitted from person to person. These diseases typically progress slowly and persist for long periods, often leading to long-term health issues and disabilities. NCDs are a major public health concern globally, accounting for a significant portion of mortality and morbidity.

It is further divided into Deficiency disease and Degenerative disease.

Deficiency Disease

Disease	Cause	Symptoms	Cure/Prevention
Scurvy	Vitamin C deficiency	Fatigue, swollen gums, joint pain	Increase intake of vitamin C-rich foods like citrus fruits, tomatoes, and leafy greens
Rickets	Vitamin D deficiency	Soft, weak bones, skeletal deformities	Ensure sufficient sunlight exposure and consume foods rich in vitamin D like fortified dairy products and fish
Beriberi	Vitamin B1 (Thiamine) deficiency	Weakness, nerve degeneration, heart issues	Include whole grains, legumes, nuts, and seeds in diet
Pellagra	Niacin (Vitamin B3) deficiency	Diarrhea, dermatitis, dementia	Intake of niacin-rich foods such as poultry, fish, and whole grains
Anemia	Iron deficiency	Fatigue, paleness, shortness of breath	Consume iron-rich foods like spinach, red meat, and iron supplements if needed
Night Blindness	Vitamin A deficiency	Difficulty seeing in low light	Increase intake of vitamin A-rich foods such as carrots, sweet potatoes, and liver
Goiter	Iodine deficiency	Swelling in the neck, thyroid dysfunction	Use iodized salt and consume iodine-rich foods like seafood and dairy products

Degenerative disease

Here’s a table summarizing some common degenerative diseases, their causes, symptoms, and potential treatments:

Disease	Cause	Symptoms	Potential Cure/Treatment
Osteoarthritis	Wear and tear of cartilage	Joint pain, stiffness, swelling, reduced range of motion	Pain relief medications, physical therapy, joint replacement surgery
Alzheimer’s Disease	Genetic factors, brain changes	Memory loss, confusion, difficulty with coordination, mood swings	Medications to manage symptoms, supportive care
Parkinson’s Disease	Loss of dopamine-producing cells	Tremors, stiffness, slowness of movement, impaired balance	Medications, physical therapy, deep brain stimulation
Diabetes (Type 2)	Insulin resistance, genetic factors	Increased thirst, frequent urination, fatigue, blurred vision	Lifestyle changes, medications, insulin therapy
Chronic Obstructive Pulmonary Disease (COPD)	Smoking, environmental factors	Shortness of breath, chronic cough, wheezing, chest tightness	Bronchodilators, steroids, oxygen therapy, pulmonary rehabilitation
Cardiovascular Disease	High blood pressure, cholesterol, smoking	Chest pain, shortness of breath, heart attack, stroke	Lifestyle changes, medications, surgery (e.g., angioplasty)
Multiple Sclerosis (MS)	Immune system attacking nerve cells	Muscle weakness, coordination problems, vision issues, cognitive changes	Medications to manage symptoms, physical therapy, disease-modifying therapies

Deficiency

It is nutrient deficiency such as Vitamin, Proteins etc.

Degenerative disease

Heart
Brain
Digestive
Lungs
Kidney
Eye

Diseases Caused by Microbes

1. Bacteria :

Here’s a table listing common bacterial diseases in humans along with their symptoms:

Disease	Causative Bacteria	Symptoms
Tuberculosis (TB)	Mycobacterium tuberculosis	Persistent cough, fever, night sweats, weight loss, fatigue, chest pain.
Cholera	Vibrio cholerae	Severe diarrhea, dehydration, abdominal cramps, nausea, vomiting.
Typhoid Fever	Salmonella typhi	High fever, weakness, stomach pain, loss of appetite, rash.
Pneumonia	Streptococcus pneumoniae	Cough with phlegm, fever, chills, shortness of breath, chest pain.
Strep Throat	Streptococcus pyogenes	Sore throat, fever, red/swollen tonsils, difficulty swallowing.
Plague	Yersinia pestis	Swollen lymph nodes, fever, chills, weakness, headache.
Diphtheria	Corynebacterium diphtheriae	Sore throat, fever, swollen glands, difficulty breathing, thick throat coating.
Tetanus (Lockjaw)	Clostridium tetani	Muscle stiffness, spasms, difficulty swallowing, fever, sweating.
Leprosy (Hansen’s Disease)	Mycobacterium leprae	Skin lesions, numbness, muscle weakness, nerve damage.
Whooping Cough (Pertussis)	Bordetella pertussis	Severe coughing fits, “whooping” sound during breath, vomiting after cough.
Botulism	Clostridium botulinum	Muscle weakness, difficulty speaking/swallowing, blurred vision, paralysis.
Gonorrhea	Neisseria gonorrhoeae	Painful urination, genital discharge, pelvic pain (in females).
Syphilis	Treponema pallidum	Sores, rashes, fever, swollen lymph nodes, organ damage (late stages).
Meningitis	Neisseria meningitidis	Severe headache, stiff neck, fever, nausea, sensitivity to light, confusion.
Anthrax	Bacillus anthracis	Skin sores, fever, cough, difficulty breathing, nausea (depending on form).

2.Virus Diseases

Here’s a table of common viral diseases in humans and their associated symptoms:

Disease	Causative Virus	Symptoms
Common Cold	Rhinovirus	Runny nose, sneezing, sore throat, mild cough, congestion, fatigue.
Influenza (Flu)	Influenza virus	Fever, chills, cough, sore throat, body aches, fatigue, headache.
COVID-19	SARS-CoV-2	Fever, cough, fatigue, loss of taste/smell, shortness of breath, aches.
HIV/AIDS	Human Immunodeficiency Virus	Weak immune system, weight loss, fever, night sweats, opportunistic infections.
Hepatitis A	Hepatitis A virus (HAV)	Fatigue, nausea, abdominal pain, jaundice, dark urine, loss of appetite.
Hepatitis B	Hepatitis B virus (HBV)	Jaundice, fatigue, abdominal pain, joint pain, dark urine, fever.
Hepatitis C	Hepatitis C virus (HCV)	Often asymptomatic, but can include fatigue, jaundice, liver damage symptoms.
Chickenpox	Varicella-zoster virus	Itchy rash, fever, fatigue, loss of appetite, fluid-filled blisters.
Measles	Measles virus	High fever, rash, cough, runny nose, conjunctivitis, white spots in mouth.
Mumps	Mumps virus	Swollen salivary glands, fever, headache, fatigue, muscle aches.
Rubella (German Measles)	Rubella virus	Mild fever, rash, swollen lymph nodes, joint pain, cold-like symptoms.
Polio	Poliovirus	Fever, sore throat, headache, stiffness, muscle weakness, paralysis (in severe cases).
Rabies	Rabies virus	Fever, anxiety, confusion, difficulty swallowing, hydrophobia, paralysis (late stage).
Dengue Fever	Dengue virus	High fever, severe headache, joint and muscle pain, rash, bleeding (severe cases).
Zika Virus Disease	Zika virus	Fever, rash, joint pain, conjunctivitis, muscle pain, headache.
Ebola Virus Disease	Ebola virus	Fever, severe headache, muscle pain, weakness, vomiting, diarrhea, bleeding.
Smallpox	Variola virus	High fever, fatigue, distinctive rash with raised blisters.
Herpes (Oral/Genital)	Herpes simplex virus (HSV)	Painful sores, blisters, itching, fever, swollen lymph nodes.

3.Fungal Diseases

Here’s a table of common fungal diseases in humans and their associated symptoms:

Disease	Causative Fungi	Symptoms
Athlete’s Foot	Trichophyton species	Itchy, red, scaly, or peeling skin on the feet, particularly between toes.
Ringworm (Tinea)	Trichophyton, Microsporum, Epidermophyton	Circular, red, itchy, and scaly patches on the skin, with a clear center.
Candidiasis (Thrush)	Candida albicans	White patches in the mouth, vaginal itching, discharge, redness, or burning.
Aspergillosis	Aspergillus species	Cough, fever, chest pain, difficulty breathing (invasive type).
Histoplasmosis	Histoplasma capsulatum	Fever, cough, chest pain, fatigue, body aches (often mild).
Cryptococcosis	Cryptococcus neoformans	Headache, fever, confusion, neck stiffness (common in immunocompromised individuals).
Blastomycosis	Blastomyces dermatitidis	Fever, cough, fatigue, chest pain, skin lesions.
Pityriasis Versicolor	Malassezia species	Discolored patches of skin, mild itching, scaling.
Sporotrichosis (Rose Gardener’s Disease)	Sporothrix schenckii	Skin ulcers, red nodules, swollen lymph nodes (cutaneous form).
Valley Fever (Coccidioidomycosis)	Coccidioides immitis	Fever, chest pain, cough, fatigue, rash (in severe cases, spreads to organs).
Fungal Nail Infections	Trichophyton species	Thickened, discolored, brittle nails, often with debris buildup.
Mucormycosis (Black Fungus)	Rhizopus and Mucor species	Facial pain, nasal congestion, blackened tissue in the nose/mouth (in severe cases).
Penicilliosis	Talaromyces marneffei	Fever, skin lesions, cough, and weight loss (common in immunocompromised individuals).
Chromycosis (Chromoblastomycosis)	Various fungi (Fonsecaea, Cladophialophora)	Warty skin lesions, slow progression to chronic infection.

4.Protozoa Diseases

Here’s a table of common protozoan diseases in humans and their associated symptoms:

Disease	Causative Protozoan	Symptoms
Malaria	Plasmodium species (P. falciparum, P. vivax, P. malariae, P. ovale)	Fever, chills, sweating, headache, muscle pain, fatigue, nausea, vomiting.
Amoebiasis	Entamoeba histolytica	Abdominal pain, diarrhea (sometimes with blood), fever, weight loss.
Giardiasis	Giardia lamblia	Diarrhea, abdominal cramps, bloating, gas, nausea, fatigue, weight loss.
Leishmaniasis	Leishmania species	Skin sores, fever, weight loss, swollen spleen and liver (visceral form).
Trypanosomiasis (Sleeping Sickness)	Trypanosoma brucei	Fever, headache, joint pain, swollen lymph nodes, confusion, sleep disturbances.
Chagas Disease	Trypanosoma cruzi	Fever, fatigue, swelling at infection site, heart and digestive complications (chronic stage).
Toxoplasmosis	Toxoplasma gondii	Flu-like symptoms, swollen lymph nodes, muscle aches (severe in immunocompromised individuals).
Cryptosporidiosis	Cryptosporidium species	Watery diarrhea, stomach cramps, nausea, fever, dehydration.
Babesiosis	Babesia species	Fever, chills, fatigue, muscle aches, nausea, dark urine.
Trichomoniasis	Trichomonas vaginalis	Genital itching, burning during urination, vaginal or penile discharge.
Balantidiasis	Balantidium coli	Diarrhea (sometimes with blood), abdominal pain, nausea, vomiting, weight loss.
Kala-Azar (Visceral Leishmaniasis)	Leishmania donovani	Fever, weight loss, darkening of the skin, enlarged spleen and liver, anemia.
Primary Amoebic Meningoencephalitis (PAM)	Naegleria fowleri	Severe headache, fever, nausea, stiff neck, confusion, seizures, coma (rare but fatal).
Cyclosporiasis	Cyclospora cayetanensis	Watery diarrhea, abdominal pain, nausea, fatigue, weight loss.

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Relationship between DNA, Genes, Chromosomes and Traits Tnpsc

Tnpsc: Genetics, DNA, Genes and Chromosomes

What is Genetics?

Genetics is the branch of biology that deals with the genes, genetic variation, and heredity of living organisms.

What is heredity?

It is the character transmission from one generation to the next generation.

What is Variation?

It is the differences exhibited by the individuals of the same species and also by the offspring of the same parent.

All the above three happen only because of chromosomes and their composition with DNA which forms the genetic material.

Father of Genetics

Gregor Johann Mendel (1822-1884), an Austrian Monk, found the basics of heredity by his experiments which are considered the foundation of modern genetics. Mendel did his experiments on the garden Pea plant.

He conducted an experiment on nearly 10000 pea plants of 34 different varieties. Mendel noted that each pea plant differs from one another. He chose 7 pairs of distinct characters from these plants they are

mendel characteristics of pea — Mendel experiment pea plant characteristics

Characteristics of Pea plant by Mendel

Pea/Seed shape is round or wrinkled
Pea/Seed colour is yellow or green
Pea/Seed coat colour is coloured or white

Pod shape is constricted or inflated
Pod colour is green or yellow
stem size is tall or short
Position of flowers is axial or terminal

The basis for success for Mendels Experiments

Choosing the pea had many advantages for experiments such as:

It is very easy to grow pure breeding Peas, as it is naturally self-pollinating.
It has a short life span as it is an annual crop and so it was feasible to go along with several generations.
Easy cross-pollination.
Contrasting character is deeply defined.
It has bisexual followers.

Some outcomes from Mendel Genetics Experiments

Factors that are passed from one generation to another are called Genes. Factors that occur in pairs and maybe alike as in pure breeding tall plants (TT) and dwarf plants (tt), it is called Homozygous.

If they are unlike (Tt) they are called Heterozygous. Two factors making up a pair of contrasting characters are called Alleles or allelomorphs, one of each pair is contributed by one parent.

The character which expresses itself is called the Dominant condition and that which is masked is called the recessive condition.

Mendel’s Laws of Genetics

Based on experiments with Monohybrid and Dihybrid cross, Mendel devised three laws called the Law of Heredity.

Law of Dominance

” When two homozygous individuals with one or more sets of contrasting characters are crossed, the characters that appear in the F1 hybrid are dominant and those that do not appear in F1 are recessive characters”.

Law of Independent assortment

“In case of inheritance of two or more pairs of characters simultaneously, the factors or genes of one pair assort out independently of the other pair.”

Law of Segregation or Law of purity of gametes

“When a pair of contrasting factors or genes or allelomorphs are brought together in a heterozygote or hybrid, the two members of the allelic pair remain together without mixing and when gametes are formed, the two separate out, so that only one enters each gamete.”

Chromosomes, DNA and Genes

Every living organism is made up of cells and the nucleus of each cell contains thin thread-like structures known as Chromosomes. In 1888, the word Chromosome was coined by Waldeyer.

The chromosomes are the transporter of hereditary material which contains the heredity data. The chromosome is packed with DNA (Deoxyribonucleic acid) which forms genetic material.

Genes are segments of DNA, that are responsible for the inheritance of a unique Phenotypic character. Genes are present in a particular place on a chromosome called its Locus.

Gene information is passed from one generation to another generation during cell division.

Structure of chromosome with Diagram

chromosome structure and packaging of dna — Ultra Structure of Chromosome

It is a thin, long thread-like structure with two identical strands called Sister chromatids. These chromatids are held together by the centromere. Each chromatid is made up of a spirally coiled thin structure called Chromonema.

The chromonema has a number of bead-like structures along the length called Chromomeres. The chromosomes are made up of DNA, RNA chromosomal proteins such as histones and non-histones, and certain metallic ions.

These proteins provide structural support to the chromosomes.

A chromosome consists of:

Primary Constriction

Two arms of a chromosome meet at a point called Primary constriction or centromere. The centromere is the region where spindle fibers attach to the chromosomes during cell division.

Secondary Constriction

Some chromosomes possess secondary constriction at any point of the chromosome. They are known as the nuclear zone or nucleolar organizer (formation of the nucleolus in the nucleus).

Telomere

The end of the chromosome is called a telomere. Each extremity of the chromosome has a polarity and prevents it from joining the adjacent chromosome. It maintains and provides stability to the chromosomes.

Telomeres act as the aging clock in every cell. Telomeres are protective sequences of nucleotides found in chromosomes. As a cell divides every time, they become shorter. Telomeres get too short to do their job, causing our cells to age.

Satellite

Some of the chromosomes have elongated knob-like appendages at one end of the chromosome known as the satellite. The chromosomes with satellites are called the sat-chromosomes.

Types of Chromosomes based on the position of the centromere

Based on the position of the centromere, the chromosomes are classified as Telocentric, Acrocentric, Submetacentric, and Metacentric.

Types of Chromosomes

Telocentric – The centromere is found on the proximal end. They are rod-shaped chromosomes.

Acrocentric – The centromere is found at the one end with a short arm and a long arm. They are also rod-shaped chromosomes.

Submetacentric -The centromere is found near the center of the chromosome. Thus forming two unequal arms and are J-shaped or L-shaped chromosomes.

Metacentric – The centromere occurs in the center of the chromosome and form two equal arms and are V-Shaped chromosomes.

Types of Chromosomes based on function

The eukaryotic chromosomes are classified into autosomes and allosomes. Autosomes contain genes that determine the somatic characters. Male and females have an equal number of autosomes.

Allosomes are chromosomes that are responsible for determining the sex of an individual. They are also called sex chromosomes or hetro-chromosomes. There are two types of sex chromosomes, X and Y-Chromosomes.

The human male has one X Chromosome and One Y chromosome. The human female has a two-X chromosome.

Karyotype

The number of chromosomes in any living organism is constant. In humans, each cell normally contains 23 pairs of chromosomes. Out of which 22 pairs are autosomes and the 23rd pair is the allosome or sex chromosome.

In the body cells of sexually reproducing organisms, the chromosome generally occurs in pairs. This condition is called diploid (2n). The gametes produced by the organisms contain a single set of chromosomes.

Hence, the gametes are said to be haploid(n). The karyotype is the number, size, and shape of chromosomes in the cell nucleus of an organism.

Idiogram is the diagrammatic representation of the karyotype of a species. It consists of all the metaphasic chromosomes arranged in homologous pairs according to decreasing length, thickness, the position of centromere, shape, etc, with the sex chromosomes placed at the end.

Structure of DNA

DNA is the hereditary material as it contains genetic information. It is the most important constituent of a chromosome. The most widely accepted model of DNA is the double-helical structure of James Watson and Francis Crick.

They proposed the 3-D model of DNA on the basis of X-ray diffraction studies of DNA obtained by Rosalind Franklin and Maurice Wilkins.

In appreciation of their discoveries on the molecular structure of nucleic acids Watson, Crick, and Wilkins were awarded the Nobel prize for Medicine in 1962.

Chemical Composition of DNA Molecule

DNA is a large molecule consisting of millions of nucleotides. Hence it is also called a polynucleotide.

Each nucleotide consists of three components.

A Sugar Molecules – Deoxyribose sugar.
A Nitrogenous Base. There are two types of nitrogenous bases in DNA. They are
Purines (Adenine and Guanine)
Pyrimidines (Cytosine and Thymine)

A Phosphate Group

Nucleoside and Nucleotide

Nucleoside = Nitrogen base + Sugar
Nucleotide = Nucleoside + Phosphate

The nucleotide is formed per the purines and pyrimidines present in them.

Watson Crick Model of DNA

According to the Watson crick model of DNA, a DNA molecule consists of two polynucleotide chains. These chains form a double helix structure with two strands that run anti-parallel to one another.

Nitrogenous bases in the centre are linked to sugar-phosphate units which form the backbone of the DNA.

Pairing between the nitrogenous base is very specific and is always between purine and pyrimidine linked by hydrogen bonds.
- Adenine (A) links Thymine (T) with two hydrogen bonds (A=T)
- Cytosine (C) links Guanin (G) with three hydrogen bonds (C=G)
- This is called the complementary base pairing.

primary structure of dna — Double Helix Structure of Dna

Hydrogen bonds between the nitrogenous bases make the DNA molecule stable. Each turn of the double helix is 34 Å (3.4nm). There are ten base pairs in a complete turn. The nucleotides in a helix are joined together by phosphodiester bonds.

Chargaff Rule of DNA base Pairing

Erwin Chargaff states that in DNA, the proportion of adenine is always equal to that of thymine. The proportion of guanine is always equal to that of cytosine.

Dna Replication

What is DNA Replication?

It is the basic process that happed within a cell. By DNA Replication, a DNA molecule produces exact copies of its own structure during the replication process.

dna replication diagram labeled — DNA Replication

DNA Replication Steps

1.Origin of Replication

The point where the replication begins is the site of origin. The strands open and separate at this point forming the replication fork.

2. Unwinding of DNA molecule

Enzymes involved in dna replication:

Helicase and Topoisomerase are the enzymes involved in DNA replication. The function of Helicase and Topoisomerase are discussed below.

Helicase – Helicase bind to the origin of replication and separates the two strands of DNA.

Topoisomerase – Topoisomerase enzyme separates the double helix above the replication fork and removes the twist formed during the unwinding process.

Each of the separated DNA strands functions as a template.

3.Formation of RNA Primer

An RNA primer is a short segment of RNA nucleotides. The primer is synthesized by a DNA template close to the origin of the replication site.

4. Synthesis of new complementary strand from the parent strand

After the RNA primer formation, nucleotides are added with the help of an enzyme DNA polymerase and a new complementary strand of DNA is formed from each of the parent strands.

The synthesis is unidirectional. In one strand, the daughter strand is synthesized as a continuous strand which is called the leading strand. In the other strand, short segments of DNA are synthesized.

This strand is called the Lagging strand. The short segments of DNA are called Okazaki fragments. The fragments are joined together by the enzymes, DNA ligase. The replication stops when the replication fork of the two sides meets at a site called terminus.

Terminus is situated opposite to the origin of a replication site.

Significance of DNA

DNA is responsible for the transmission of hereditary information from one generation to the next generation.DNA contains information required for the formation of proteins.

It controls the development process and life activities.

Sex determination in Humans

Human has 23 pairs of chromosomes out of which 22 pairs are autosomes and the 23rd pair is the sex chromosome. The female gametes or the eggs formed are similar in their chromosome type (22 + XX).

Therefore human females are homogametic. If the egg (X) is fused by the X-bearing sperm an XX individual (female) is produced.If the egg (X) is fused by the Y-Bearing sperm an XY Individual (male) is produced.

The sperm produced by the father determines the sex of the child. The mother is not responsible for determining the sex of the child.

Fertilization of the egg (22 + X) with a sperm (22 + X) will produce a female child (44 + XX).

Fertilization of the egg (22 + X) with a sperm (22 + Y) will give rise to a male child (44 + XY).

Mutation

The term mutation was introduced by Hugo De Vries in 1901. He observed phenotypic changes in the evening primrose plant, Oenothera lamarckiana.

What is Mutation in Biology?

A mutation is an inheritable sudden change in the genetic material (DNA) of an organism. Mutations are classified into two main types of mutation. That is

Classification of mutation

Chromosomal Mutation
Gene Mutation

Chromosomal Mutation

The sudden change in the structure or number of chromosomes is called a chromosomal mutation. This results in

Structural changes in chromosomes – This occurs due to error in cell division. Changes in the number and arrangement of genes take place as a result of deletion, duplication, inversion and translocation in chromosomes.

Number changes in Chromosomes – This involves addition or deletion in the number of chromosomes present in a cell. This is called Ploidy.

There are two types of Ploidy.

Euploidy

Aneuploidy

Euploidy

Euploidy is the condition in which the individual bears more than the usual number of diploid (2n) chromosomes.
If an individual has three haploid sets of chromosomes, the condition is called Tri-ploidy (3n).
Triploid plant and animals are typically sterile.
If it has four haploid sets of chromosomes, the condition is called tetra-ploidy (4n).
Tetraploid plants are advantageous , as its increases fruits and flower size.

Aneuploidy

It is the loss or gain of one or more chromosomes in a set.

It is of three types.

Monosomy (2n-1)
Trisomy (2n+1)
Nullisomy (2n-2)

Down’s Syndrome is one of the commonly known aneuploid conditions.

Down Syndrome

This condition was first identified by a doctor named Langdon Down in 1866.

Down Syndrome Causes and Symptoms

Down Syndrome Causes

It is a genetic condition in which there is an extra copy of chromosome 21 (Trisomy 21).

Down Syndrome Symptoms

It is associated with mental retardation, delayed development, behavioral problems, weak muscle tone, vision, and hearing disability are seen in these children.

Gene or Point Mutation

What is Point Mutation?

Gene mutation is the changes occurring in the nucleotide sequence of a gene. It involves substitution, deletion, insertion, or inversion of a single or more than one nitrogenous base. Gene alternation results in abnormal protein formation in an organism.

Sickle Cell Anaemia

Sickle cell Anemia is caused by the mutation of a single gene, which is a mutation in the hemoglobin-Beta gene found on chromosome 11. Alteration in the gene brings a change in the structure of the protein part of the hemoglobin molecule.

Due to the change in the protein molecule, the red blood cell (RBC) that carries the hemoglobin is sickle-shaped.

Head mirror Uses

Uses of Concave Mirror

Dentist or ENT specialist Head Mirror
Makeup Mirror
Reflector in torches.
Headlight in vehicles
Search Light

// Note: Images formed by Concave mirrors are diminished and inverted, yet they are used in telescopes.

The head mirror used by ent doctors is concave or convex?

The heart mirror used by End doctors is a Concave mirror. It is because the concave mirror combines all the light rays from the object in the direction parallel to the principal axis onto its focus and also focuses the object rays in the desired part.

Light Tnpsc Pdf

Bibliography

Tamil Nadu Samacheer Kalvi. 9th Science. First Edition ed., vol. 3, Tamil Nadu Text Book Corporation, 2018. 3 vols. Department of School Education, Tamilnadu Government, http://tnschools.gov.in/textbooks.

Health and hygiene Tnpsc, Food and Health awareness campaign

This article is written for Tnpsc General Science -Biology, for the topic Health and Hygiene.

Health and hygiene

Health and hygiene play a crucial role in maintaining overall well-being and preventing the spread of diseases. Here are some key points to keep in mind:

Personal Hygiene: Regularly washing your hands with soap and water for at least 20 seconds helps eliminate germs. It’s important to wash your hands before eating, after using the restroom, and after coughing or sneezing.
Oral Health: Brush your teeth at least twice a day and floss daily to remove plaque and prevent dental issues. Don’t forget to visit your dentist for regular check-ups and cleanings.
Proper Nutrition: Maintaining a balanced diet rich in fruits, vegetables, whole grains, and lean proteins is essential for good health. Drink plenty of water to stay hydrated.
Physical Activity: Engage in regular exercise to keep your body fit and promote a healthy cardiovascular system. Aim for at least 30 minutes of moderate-intensity activity most days of the week.
Adequate Sleep: Getting enough sleep is vital for your overall health and well-being. Aim for 7-9 hours of quality sleep each night to ensure proper rest and rejuvenation.
Stress Management: Find healthy ways to cope with stress, such as practicing meditation, deep breathing exercises, or engaging in hobbies you enjoy. Avoid excessive alcohol consumption and tobacco use.
Vaccinations: Stay up to date with necessary vaccinations to protect yourself and others from contagious diseases. Consult with your healthcare provider to ensure you’re following the recommended vaccination schedule.

Remember, prioritizing health and hygiene not only benefits you but also contributes to the well-being of your community.

Food

The basic necessity of life. Food is defined as any substance from a plant or animal that provides nutrition like protein, fats, vitamins, minerals, and carbohydrates for growth, energy, repair of body parts such as bones and tissue and provides protection from diseases.

health and hygiene tnpsc — Health and hygiene Tnpsc

Classification of nutrients by predominant function

The nutrient is classified into Proteins, Minerals, Carbohydrates, Fats, Vitamins, and Water

Carbohydrates

These are organic compounds made of carbon, hydrogen, and oxygen in the ratio 1:2:1. It is the main source of energy.

Edible sugar, cellulose, starch, rice, etc are some sources. Glucose is a monosaccharide, sugar is a disaccharide, and cellulose in the vegetable is a polysaccharide.

Honey, sugarcane, and fruits are sources of sucrose. Starch is from rice, potatoes, and bread.

Glycogen is stored in the muscles and liver of living organisms. A plant cell is made of cellulose and other complex organic compounds.

3 classification of starch/carbohydrates — carbohydrates classification

Deficiency of Carbohydrates

The body suffers from glucose, then it takes energy from proteins and fats. Dizziness, physical and mental weakness is caused due to suffering of the central nervous system from insufficient glucose. It causes low blood sugar called Hypoglycemia.

Proteins

It is an essential nutrient, the building block of body tissue, and also a fuel source.

Protein provides more energy than carbohydrate that is carbohydrates provides 4 kcal(17 kJ) per gram and lipids provides 9 kcal(37 kJ) per gram.

The most important point of protein is its amino acid composition. Proteins are made of polypeptide chains which are composed of amino acids that are linked by peptide bonds.

Proteins are broken down into smaller polypeptides during digestion in the stomach and small intestine by the action of proteases.

Proteases are important for the absorption of essential amino acids that cannot be synthesized by the body.

There are 9 essential amino acids(EAA) that are crucial for human needs and to prevent malnutrition. They are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.

Fats

Known as triglycerides that are esters of free fatty acid chains and glycerol. Fat is crucial for structural and metabolic functions.

An essential part of the diet for most heterotrophs. During digestion, Lipase enzymes break down fats in the small intestine.

These essential fatty acids cannot be produced in the body therefore it is taken into the diet. There are two essential fatty acids (EFAs) that are alpha-linolenic acid (omega-3 fatty acid) and linoleic acid(omega-6 fatty acid).

Deficiency of Fats

Eating disorders, Causes Vitamin deficiencies such as Infertility, Night Blindness, etc as fat helps in absorbing vitamins, inflammatory bowel disease, cystic fibrosis, pancreatic insufficiency, etc.

Vitamins

Essential nutrients are taken a very minute amount to maintain special functions such as body health etc.

Vitamins are not produced by the body, so they must be taken in a small amount through diet.

Minerals

A chemical element that is very vital to perform certain functions in the body.

Minerals are inorganic substances produced by the earth which important to the physiological process and they are important constituents of teeth, bones, tissues, blood, muscles, and nerve cells.

5 major minerals in humans are calcium, phosphorus, potassium, sodium, and magnesium. The remaining minerals are called Trace elements that are Iron, cobalt, copper, zinc, manganese, chlorine, sulfur, molybdenum, iodine, and selenium.

Facts on essential nutrients and their functions

Dr. Funk coined the term Vitamin. Vitamin A was first as A is the first letter of the alphabet.

Vitamin D, helps bones absorb calcium. Iron from meat (heme iron) is readily absorbed.

Irom from the plant (non-heme iron) required Vit-C to get absorbed. Vit-D is produced when the skin is exposed to sunlight, as skin dehydro cholesterol is converted into Vit-D. Vit-D is also called as Sunshine vitamin.

The world iodine deficiency day is celebrated on October 21.

Water

Vital as a solvent, the body’s solutes dissolve in water and are also important for metabolic processes. There are two types of metabolism with respect to water that are anabolism and catabolism.

Anabolism-Water is removed from molecules by enzymatic chemical reactions to synthesize larger molecules such as starch, triglycerides, and proteins.

In catabolism, water is used for breaking bonds to produce smaller molecules such as glucose, fatty acids, and amino acids which are used for fuel and other purposes.

Without water, body metabolism will not exist.

Types of nutritional disorders and symptoms

Fat-Soluble Vitamins- Vitamin A, D, E, K

1.Vitamin A(Retinol)

Sources of Vitamin A-Carrot, papaya, leafy vegetable, fish liver oil, egg yolk, liver, dairy products.

Disorder- Xerophthalmia, Nyctalopia (Night Blindness)

Symptoms-Dryness of Cornea( Xerophthalmia ), Nyctalopia -unable to see at night and dim light, scally skin.

2.Vitamin-D (Calciferol)

Egg, liver, dairy, fish, sunlight

Disorder- Rickets in Children

Symptoms- Bow Legs, defective ribs, development of pigeon chest.

3.Vitamin E(Tocopherol)

Whole wheat, meat, vegetable oil, milk

Disorder- Sterility in rats, Reproductive abnormalities.

Symptoms- Sterility

4.Vitamin-K(Derivative of Quinone)

Leafy vegetables, soybeans, milk

Disorder- Blood clotting is prevented.

Symptoms- Excessive bleeding due to delayed blood clotting.

Water-Soluble Vitamins- Vitamin B1,B2,B3,B6,B12,C

1.Vitamin B1(Thiamine)

Whole grains, yeast, eggs, liver, sprouted pulses.

Disorder-Beriberi

Symptoms- degenerative nerve & muscle weakness, paralysis

2.Vitamin B2(Riboflavin)

Milk, egg, liver, green, vegetables, whole grains

Disorder- Ariboflavinosis(cheilosis)

Symptoms- Eye Irritation, Dry Skin, inflammation of lips, fissures in the corner of the mouth.

3.Vitamin B3(Niacin)

Milk, eggs, liver, lean meat, groundnuts, bran

Disorder- Pellagra

Symptoms- Inflammation of skin, loss of memory, diarrhea

4.Vitamin B6(Pyridoxine)

Milk, eggs, germs of grains and cereals, rice, polishings

Disorder- Dermatitis

Symptoms-Scaly skin, nerve disorders

5.Vitamin B12(Cyanocobalamine)

Milk, meat, liver, pulses, cereals, fish

Disorder- Pernicious anemia

Symptoms- Decrease in red blood cell production, degeneration of the spinal cord

6.Vitamin C(Ascorbic Acid)

Leafy vegetables, sprouts, citrus fruits like gooseberry(Amala), lemon, orange

Disorder- Scurvy

Symptoms- Swollen and bleeding gums, delay in wounds healing, teeth and bones malformed.

Protein Energy Malnutrition(PEM)

Kwashiorkor

Severe protein deficiency affects children age 1-5 whose dietary intake is mainly carbohydrate but poor protein intake.

Marasmus

Affects infants below the age of one, who have a poor intake of carbohydrates, fats, and proteins.

Functions of minerals in the body

Macro Nutrients

Calcium

Sources-Dairy, beans, cabbage, eggs, fish

The function of Calcium-Constitution of bone, the enamel of teeth, clotting of blood and controls muscle contraction

Disorder-Bone deformities, poor skeletal growth, osteoporosis in adults.

Sodium

Sources- Table Salt.

The function of Sodium- maintains fluid balance and is involved in neurotransmission.

Muscular cramps, nerve impulses do not transmit.

Potassium

Sources- Banana, sweet, potato, nuts, whole grains, citrus fruits.

The function of Potassium- Regulates nerve and muscle activity

Disorder-Muscular fatigue, nerve impulses do not transmit.

Micro Nutrients

Iron

Sources- Spinach, dates, greens, broccoli, whole cereals, nuts, fish, liver

The function of Iron- An important component of hemoglobin

Disorder- Anaemia

Iodine

Sources- Milk, Seafood, Table Salt.

Functions of Iodine- Formation of Thyroid hormones

Disorder- Goitre

Vitaminosis

Disease caused by excessive intake of Vitamins is called Vitaminosis.

Hyper Vitaminosis is a condition of abnormally high storage of vitamins which can lead to toxic symptoms

Example: Excess vitamin-A intake can lead to Vitaminosis A.

A right balanced diet is required for preventing Vitaminosis.

Healthy food pyramid

The food on top of the pyramid should be consumed in less quantity such as fat and oil.

The food at the bottom of the pyramid should be consumed more compared to the top of the pyramid.

Food Spoilage

undesirable change of fresh food at normal state to a condition which is not suitable for human consumption.

Signs of food spoilage are changed in color, bad odor, texture, and taste change.

Two reasons for spoilage are Internal and External factors.

External factors- adulterants, contaminated utensils, lack of storage, poor hygiene.

Internal factor- Enzymatic activities and moisture content of the food.

Control and Prevention of Food spoilage

Food Preservation- Process to prevent food from decay or spoilage.

Food is preserved to increase the shelf life of food, to retain the color/texture /flavor / and nutrition value, to increase food supply, decrease food waste, add variety to the food.

Methods of Food Preservation

Dehydration/ Drying

The process of removing water content from the food. It is done by Sun Drying(Fish, Cereals) or vacuum drying (e.g milk powder, cheese powder), or hot air drying (e.g grapes, dry fruits, potato flakes). Dried neem leaves, turmeric are used to prevent grains from insects and beetles.

Smoking

Meat and fish are exposed to smoke, the food is dried using smoke that preserves the food.

Irradiation

The food is exposed to controlled ionizing radiation like x-ray, gamma rays, or UV rays to kill microbes to prevent the food from spoilage. This process is also called cold pasteurization as the product is not heated. Done on onions and potatoes to increase its shelf life.

Use of Inert Gas

Nitrogen gas is filled in air-tight packets containing food which inhibits the growth of fungus. Ex: Used in Potato wafers.

Cold Storage

Storing in a refrigerator inhibits the biological and chemical reaction thus preventing food from spoilage.

Freezing

Storing food below zero degrees Celcius at which microorganisms cannot grow and the metabolic reaction is reduced. Deep Freezing – -23 to -30 degrees Celcius.

Pasteurization

Named after Louis Pasteur that involves boiling milk to 63-degree Celcius for about 30 minutes and suddenly cooling to kill the microbes present. Louis Pasteur also developed vaccines for rabies and anthrax.

Canning

Food products are stored in clean, steamed airtight containers under pressure and then sealed and subjected to high temperature and cooled to destroy microorganisms.

Using Preservative

There are two types of preservatives Natural and Synthetic.

Natural Preservative

Salt

Salt removes water from food by the process of osmosis. Example Meat, Fish, Raw mangoes are preserved using this process also referred to as pickles.

Sugar

Sugar/Honey is also used to increase the shelf life of fruits. The process is similar to salt. Ex Jam, Jellies, squash. The hygroscopic nature of sugar/honey, reduces the water in food, and prevents it from oxidation, and prevents spoilage from microbes.

Oil

The oil prevents food from external contact such as air, prevents micro growth over the food.

Excess content oil, salt, and sugar make food unsafe for consumption, especially for Diabetes, obesity, and heart diseases.

Synthetic Preservative

Sodium benzoate, citric acid, vinegar, sodium meta bisulfate, and potassium bisulfate are added to jam, jellies, sauces, and other packed and ready-to-eat items.

October 16th is world food day

Adulterants and Diseases

The addition or removal of any substances to the food, as the natural composition and quality of food, get affected.

Today every food is adulterated such as Milk, cereals, meat, etc.

Classification of Adulterants

Adulterants are classified into Natural, Unintentional, and Intentional.

Natural Adulterants

Present or grow naturally in food, chemical, or organic substance or microbes such as fungus.

Example: Toxin substances in poisonous mushrooms, prussic acid in apple seeds, cherry and peach pits, marine toxin, fish, oil poisoning, pollution in the air, water, and land.

Incidental food adulteration or Unintentional adulteration

Added without knowing it is harmful. Generally done while packing or transporting.

An example is Pesticide residues( adding pesticides to crop and ignorance of clearing it), Rodent( larva, mice, and insects bits, this food and spread the disease during storage, Microbial containing such E.Coli(Escherichia coli), Salmonella in fruits, meats.

Intentionally added adulterants

Intentionally added to food for financial gain.

Some of Intentionally added Adulterants

Additives and preservatives such as vinegar, citric acid, sodium bicarbonate(baking soda), hydrogen peroxide in milk, modified food starch, food flavor, the artificial sweetener.

Artificial ripening of fruits using Calcium Carbide.

Artificial coloring agents use a chemical such as Metallic lead for green leafy vegetables, bitter gourd, green peas.

Edible synthetic wax-like shellac or carnauba wax coated on apple, pear to give a shiny appearance.

Growth hormones for Cattle, Poultry, and also for the plant.

Diseases caused by adulteration of food are Fever, Kidney Disorder, Nausea and Diarrhoea etc

Difference between naturally ripened fruit and artificially ripened fruit — Adulteration in fruits

Some simple techniques used to detect adulterants at home

Milk

Milk flows slowly and leaves a trail behind when a drop of milk is on a slanting polished surface. While adulterated milk with water flow fast and leaves no trail behind.

Honey

Pure honey burns while adulterated honey produces a cracking sound.

Sugar

Sugar Dissolve completely in water, while sugar adulterated with chalk powder settles down.

Coffee

The coffee powder floats in water, while coffee powder adulterated with tamarind powder settles down.

Sand grit, marble, stones present in food grain can be removed by handpicking, sorting, and washing.

Quality Standard Control Agencies

ISI, Agmark, Fpo, FCI.

FCI(Food Corporation of India)

Set up in the year 1965 for safeguarding the interest of farmers, distribution of food, maintaining food stock for national food security, and regulating the market price of food grains.

ISI (Indian Standards Institution)

Now known as Bureau of India Standard (BIS). It certified electrical and electronic appliances.

AGMARK (Agricultural Marking)

Agmark certifies agricultural and livestock products such as pulses, honey, butter, etc.

FPO (Fruit Process Order)

Certified vegetable and fruit products such as Jam, Sauce, Pickles, etc.

Food Safety and Standards Authority of India

FSSAI regulates and supervises food safety and quality for promoting public health.

Codex Alimentarius -Global standard for foods approved by World Trade Organisation(WTO).