10th Science Important Points | Quick Revision & Key Concepts

Welcome to your ultimate revision hub for Class 10 Science. This curated list of important points breaks down complex chapters into bite-sized, easy-to-remember facts. Whether you are doing a final review before the exam or mastering core physics, chemistry, and biology concepts, these key takeaways will help you boost your confidence and scores.

10th Science - Important Points

The value of acceleration due to gravity on the surface of the moon is 1.625 m s^-2.
Acceleration due to gravity for Earth (at sea level) = 9.8 m s^-2.
Value of 'g' is zero at the Centre of the Earth.
Mass of the Earth (M) = 5.972 × 10²⁴ kg. The radius of the Earth is R = 6378 km.
Lift is moving upward with an acceleration 'a'. R = m(g + a), Apparent weight is greater than the actual weight.
Lift is moving downward with an acceleration 'a'. R = m(g - a), Apparent weight is lesser than the actual weight.
Lift is at rest. R = mg, Apparent weight is equal to the actual weight.
Lift is falling down freely. R = 0, Apparent weight is equal to zero.
The first telescope was invented by Johann Lippershey in 1608.
Kepler invented Telescope in 1611, which was fundamentally similar to the astronomical telescope.
Astigmatism can be corrected by using cylindrical lenses.
Presbyopia is also called as 'old age hypermetropia'. This can be corrected by 'bifocal lenses'.
Nichrome is a conductor with highest resistivity equal to 1.5 × 10^-6 Ω m. Hence, it is used in making heating elements.
The horse power (hp) is a unit in the foot-pound-second (fps) or English system, sometimes used to express the electric power. It is equal to 746 watt.
Consumption of electricity is based on two factors: (i) Amount of electric power and (ii) Duration of usage.
In India, domestic circuits are supplied with an alternating current of potential 220/230 V and frequency 50 Hz.
In countries like USA and UK, domestic circuits are supplied with an alternating current of potential 110/120 V and frequency 60 Hz.
The first LED television screen was developed by James P. Mitchell in 1977.
In 2009, SONY introduced the first commercial LED Television.
LCD: Liquid Crystal Display.
LED: Light Emitting Diode.
Uranium, named after the planet Uranus, was discovered by Martin Klaproth, a German chemist in a mineral called pitchblende.
Electron Volt (eV) is the unit used in nuclear physics to measure the energy of small particles. 1 eV = 1.602 × 10^-19 joule.
1 MeV = 10⁶ eV. The energy released in a nuclear fission process is about 200 MeV.
This repulsive force will be overcome by the kinetic energy of the nuclei at higher temperature of the order of 10⁷ to 10⁹ K.
The nuclear bomb that was dropped in Hiroshima during World War II was called as 'Little boy'. It was a gun-type bomb which used a uranium core. The bomb, which was subsequently dropped over Nagasaki was called as 'Fat man'. It was an explosion type bomb, which used a plutonium core.
Sun fuses about 620 million metric tons of hydrogen each second and radiates about 3.8 × 10²⁶ joule of energy per second.
When this energy is radiated towards the Earth, it decreases in its intensity. When it reaches the Earth its value is about 1.4 kilo joule per unit area in unit time.
How old is our mother Earth? Any guess? It is nearly 4.54 × 10⁹ years (around 45 Crore 40 lakh years).

Father of Plant Anatomy: Nehemiah Grew.
Sachs classified tissue system in plants into three types.
Light dependent reaction was discovered by Robin Hill.
Melvin Calvin, an American biochemist, discovered chemical pathway for photosynthesis.
C.N.R. Rao is working on technology of artificial photosynthesis to produce Hydrogen fuel.
Kolliker discovered Mitochondria.
Mitochondria is the power houses of the cell or ATP factory of the cell.
ATP: Adenosine Triphosphate.
ADP: Adenosine Diphosphate.
NAD: Nicotinamide Adenine Dinucleotide.
NADP: Nicotinamide Adenine Dinucleotide Phosphate.
TCA: Tricarboxylic Acid Cycle.
ETC: Electron Transport Chain.
Leeches do not have ears, hence can sense vibrations through their skin.
Leeches have 2 to 10 tiny eyes, which helps them to locate their food.
Leeches can suck blood five times more than their body weight.
It may take more than a year for the complete digestion and absorption of a full meal.
Blood letting is a technique of bleeding in a patient to remove toxic impurities from the body.
The pygmy rabbit was listed as a threatened species in Washington in 1990, because of decline in its population size and distribution due to habitat loss.
In March 2003, the Columbia Basin Pygmy Rabbit was federally listed as an endangered species.
The scientific name of the Indian cattle leech is Hirudinaria granulosa which belongs to Phylum Annelida.
The scientific name of the common rabbit is Oryctolagus cuniculus. It represents Phylum Chordata and Class Mammalia.
Anaemia: Decrease in number of erythrocytes.
Leucocytosis: Increase in the number of leukocytes.
Leukopenia: Decrease in number of leukocytes.
Thrombocytopenia: Decrease in the number of thrombocytes.
Closed circulatory system was discovered by William Harvey (1628) who is regarded the Father of Modern Physiology.
Neurogenic and Myogenic Heart Beat: Neurogenic heart beat is initiated by a nerve impulse caused from a nerve ganglion situated near the heart (e.g., Annelids, most arthropods). Myogenic heart beat is initiated by a specialized group of modified heart muscle fibres (e.g., Mollusca and Vertebrates).
Heart chambers in vertebrate animals:
1. Two chambered: Fishes 2. Three chambered: Amphibians 3. Incomplete four chambered: Reptiles 4. Four chambered: Aves, Mammals and Crocodiles (Reptile)
Atrioventricular bundle was discovered by His (1893). So it is called Bundle of His.
The concept of blood grouping was developed by Karl Landsteiner (1900). He identified blood groups A, B and O.
AB blood group was recognized by Decastello and Sturli (1902).
Sphygmomanometer is a clinical instrument used to measure blood pressure when a person is in a relaxed and resting condition.
A stethoscope is used to detect the sound produced by the internal organs of human body.
In a healthy adult during normal resting condition systolic and diastolic blood pressure is expressed as 120mm/80mm Hg.
A prolonged or constant elevation of blood pressure is a condition known as hypertension (High blood pressure) which can increase the risk of heart attack and stroke.
Decrease in blood pressure is termed hypotension (Low blood pressure).
The expansion of the artery every time the blood is forced into it is called pulse. Normal pulse rate ranges from 70-90/min.
The heart normally beats 72-75 times per minute.
Arteries are thick and elastic vessels that carry blood away from the heart to various organs of the body.
Veins are thin and non-elastic vessels that transport blood to the heart from the different organs.
Capillaries are narrow tubes formed by branching of arterioles which then unite to form the venules and veins. They are about 8 μm in diameter.
Plasma: It is slightly alkaline, containing non-cellular substance which constitutes about 55% of the blood. Organic substances like proteins, glucose, urea, enzymes, hormones, vitamins and minerals are present in the plasma.
Dew like water droplets on the leaves of grass seen in the early mornings, when the climate is humid and excess of water is present in the plants, the excess water is exudated in the form of liquid. This is due to root pressure. This phenomenon is called Guttation which takes place through specialized cells called Hydathodes.
A neuron or nerve cell is the structural and functional unit of the nervous system. It is the longest cell of the human body with a length of over 100 μm.
Each neuron can transmit 1,000 nerve impulses per second and make as many as ten thousands of synaptic contacts with other neurons.
Meningitis is an inflammation of the meninges. It can occur when fluid surrounding the meninges becomes infected. The most common causes of meningitis are viral and bacterial infections.
The human brain constitutes nearly 60 percent of fat. The most crucial molecules that determine our brain's integrity and ability are Essential Fatty Acids (EFAs). EFAs cannot be synthesised and must be obtained from food. Fish, green leafy vegetables, almond, and walnut are rich sources of EFAs.
Electroencephalogram (EEG) is an instrument which records the electrical impulses of brain. An EEG can detect abnormalities in the brain waves and help in diagnoses of seizures, epilepsy, brain tumors, head injuries, etc.
The brain is suspended in a special fluid environment called cerebrospinal fluid (CSF).
Among all the plant hormones auxins, cytokinins and gibberellins promote plant growth while abscisic acid and ethylene inhibit plant growth.
The term auxin was introduced by Kogl and Haagen-Smith (1931).
Charles Darwin (1880), observed unilateral growth and curvature of canary grass (Phalaris canariensis) coleoptiles.
Phenyl Acetic Acid (PAA) and Indole 3 Acetonitrile (IAN) are natural auxins. Indole 3 Butyric Acid (IBA), Indole-3 Propionic Acid, α-Naphthalene Acetic Acid (NAA), 2, 4, 5-T (2,4,5-Trichlorophenoxy Acetic Acid) are some of the synthetic auxins.
Kurosawa (1926) observed Bakanae disease or foolish seedling disease in rice crops.
This internodal elongation in rice was caused by the fungus Gibberella fujikuroi. The active substance was identified as Gibberellic acid.
Cytokinin was first isolated from Herring fish sperm. Zeatin was the cytokinin isolated from Zea mays. Cytokinin is found abundantly in liquid endosperm of coconut.
The branch of biology which deals with the study of the endocrine glands and its physiology is known as 'Endocrinology'. Thomas Addison is known as Father of Endocrinology.
English physiologists W. M. Bayliss and E. H. Starling introduced the term hormone in 1909. They first discovered the hormone secretin.
Melatonin is a hormone produced by the pineal gland. It is known as a 'time messenger'. It signals night time information throughout the body.
Edward C. Kendall in 1914 first crystallised thyroxine hormone.
Charles Harrington and George Barger identified the molecular structure of thyroxine in 1927. Thyroid gland requires 120 μg of iodine everyday for the production of thyroxine.
Human insulin was first discovered by Fredrick Banting, Charles Best and MacLeod in 1921.
Insulin was first used in treatment of diabetes on 11th January 1922.
The cortisol hormones of adrenal cortex serve to maintain the body in living condition and recover it from the severe effects of stress reactions. Thus an increased output of cortisol is "life saving" in "shock conditions". It is also known as life-saving hormone.
It secretes two hormones namely a. Epinephrine (Adrenaline) b. Norepinephrine (Noradrenaline). They are together called as "Emergency hormones". It is produced during conditions of stress and emotion. Hence it is also referred as "flight, fright and fight hormone".
Thyroid hormone is also known as personality hormone.
The pollination with the help of wind is called anemophily.
Pollination with the help of insects like honey bees, flies is called entomophily.
The pollination with the help of water is called hydrophily.
When pollination takes place with the help of animals, it is called Zoophily.
The number of primordial follicles in newborn female child ranges over 7 million and during reproductive period (at puberty) the number is around 60,000 to 70,000.
During a woman's lifetime, she will only ovulate 300 to 400 of the 1-2 million eggs she was initially born with.
On the other side, men will produce over 500 billion sperms in their lifetime.
Menstruation is a periodical phenomenon that continues from puberty to menopause. This will happen if the released ovum is not fertilized by the sperm. Lack of menstruation generally indicates pregnancy.
Normally one egg matures in the ovary each month. Ovulation is the rupture of the follicle releasing the egg or ovum. The uterus prepares itself to receive the fertilized egg every month. The uterine lining becomes thick and spongy for implantation of the fertilized egg.
The milk produced from the breast during the first 2 to 3 days after child birth is called colostrum. It contains immune substances and provides immunity to the new born which is essential for the body.
Sometimes ovaries release two eggs and each is fertilised by a different sperm, resulting in Non-Identical Twins (Fraternal Twins). If a single egg is fertilised and then divides into two foetuses, Identical Twins develop.
The inverted red triangle is a symbol of family planning in India for family welfare. It is displayed prominently at all hospitals, primary health clinics and family welfare centres where any help or advice about family planning is available free of cost. The symbol is displayed along with a slogan Small Family, Happy Family.
Every year May 28 is observed as Menstrual Hygiene day to make girls and women aware of maintaining menstrual hygiene and importance of menstrual hygiene for good health. By way of awareness through films, discussions and campaigns menstrual hygiene has taken quite the centre stage in recent days.
The menstrual hygiene scheme to provide subsidized sanitary napkins was launched by the Health ministry in 2011. In Tamil Nadu, UNICEF has developed an affordable incinerator that uses firewood to handle sanitary napkin waste at schools and special wells are equipped where sanitary napkins are composted.
Punnett square is a checkerboard form devised by a British geneticist R.C. Punnett for the study of genetics. It is a graphical representation to calculate the probability of all possible genotypes of offsprings in a genetic cross.
T.H. Morgan was awarded Nobel Prize in 1933 for determining the role of chromosomes in heredity.
Telomeres act as aging clocks in every cell. Telomeres are protective ends 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.
Chargaff rule of DNA base pairing: Erwin Chargaff states that in DNA, the proportion of adenine is always equal to that of thymine and the proportion of guanine is always equal to that of cytosine.
Sickle cell anaemia is caused by the mutation of a single gene. Alteration in the gene brings a change in the structure of the protein part of haemoglobin molecule. Due to the change in the protein molecule, the red blood cell (RBC) that carries the haemoglobin is sickle shaped.
Euploidy: It 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 triploidy (3n). Triploid plants and animals are typically sterile. If it has four haploid sets of chromosomes, the condition is called tetraploidy (4n). Tetraploid plants are advantageous as they often result in increased fruit 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) and Nullisomy (2n-2). In man, Down's syndrome is one of the commonly known aneuploid conditions.
Down's syndrome: This condition was first identified by a doctor named Langdon Down in 1866. It is a genetic condition in which there is an extra copy of chromosome 21 (Trisomy 21).
Dr. Norman E. Borlaug, an American agronomist, the "Father of the Green Revolution", received the Nobel Peace Prize in 1970.
Father of Indian Green Revolution: Dr. M. S. Swaminathan.
Dr. G. Nammalvar: Tamil agricultural scientist, environmental activist and organic farming expert.
Dolly was the first cloned female sheep, developed by Dr. Ian Wilmut and his colleagues at the Roslin Institute, Scotland in July 1996.
Eli Lilly and Company, United States, in 1979 first started commercial production of human insulin by using rDNA technology.
DNA fingerprinting was developed by Alec Jeffreys.
The Ministry of Women and Child Development championed the introduction of the Protection of Children from Sexual Offences (POCSO) Act, 2012.
The National Commission for Protection of Child Rights (NCPCR) was set up in March 2007 under the Commissions for Protection of Child Rights (CPCR) Act, 2005.
World Health Organization (WHO) 1984 suggested the use of the term drug dependence in place of drug addiction or drug abuse.
International Day against Drug Abuse and Illicit Trafficking — June 26.
Narcotic Drugs and Psychotropic Substances Act was introduced in 1985.
Anti-Tobacco Act was passed on May 1st 2004.
May 31st is observed as No Tobacco Day (World Anti-Tobacco Day).
HDL (High Density Lipoprotein) or "good" cholesterol lowers risk of heart disease while LDL (Low Density Lipoprotein) or "bad" cholesterol increases risk of heart disease.
Cardiovascular disease (CVD) is associated with diseases of the heart and blood vessels. Coronary heart disease (CHD) is the most common form and is caused by deposition of cholesterol in the blood vessels.
Desirable level for blood cholesterol should be less than 200 mg/dl for Indians. The risk of coronary heart disease increases slowly as blood cholesterol levels increase from 200 to 300 mg/dl.
World Cancer Day — 4th February.
National Cancer Awareness Day — 7th November.
Types of Tumours: Benign tumours (Non-malignant tumours) and Malignant tumours.
Dr. Suniti Solomon pioneered HIV research and treatment in India. She set up the first voluntary testing and counselling centre and an AIDS Research group in Chennai during the 80s. Her team was the first to document evidence of HIV infection in India in 1985 (First Indian AIDS patient in Chennai).

Acoustical wonder of Golconda fort (Hyderabad, Telangana): The Clapping portico in Golconda Fort is a series of arches on one side, each smaller than the preceding one. So, a sound wave generated under the dome would get compressed and then bounce back amplified sufficiently to reach a considerable distance.
Rarer and Denser Medium (for Sound): The medium in which the velocity of sound increases compared to other medium is called rarer medium (Water is rarer compared to air for sound). The medium in which the velocity of sound decreases compared to other medium is called denser medium (Air is denser compared to water for sound).
Whispering Gallery: One of the famous whispering galleries is in St. Paul's Cathedral Church in London. It is built with elliptically shaped walls. When a person is talking at one focus, his voice can be heard distinctly at the other focus due to the multiple reflections of sound waves from the curved walls.
Relative Atomic Mass is only a ratio, so it has no unit. If the atomic mass of an element is expressed in grams, it is called Gram Atomic Mass.
Gram Atomic Mass of hydrogen = 1 g; Gram Atomic Mass of carbon = 12 g Gram Atomic Mass of nitrogen = 14 g; Gram Atomic Mass of oxygen = 16 g
Relative Molecular Mass is only a ratio, so it has no unit. If the molecular mass of a compound is expressed in grams, it is called Gram Molecular Mass.
Gram Molecular Mass of water = 18 g; Gram Molecular Mass of CO₂ = 44 g Gram Molecular Mass of ammonia = 17 g; Gram Molecular Mass of HCl = 36.5 g
Noble gases show no tendency to accept electrons because the outer s and p orbitals of noble gases are completely filled. No more electrons can be added to them and hence their electron affinities are zero.
Dilute or concentrated nitric acid does not attack aluminium, but it renders aluminium passive due to the formation of an oxide film on its surface.
If hydrogen peroxide is poured on a wound, it decomposes into water and oxygen. The gaseous oxygen bubbles away as it is formed and thus prevents the formation of H₂O₂.
Food kept at room temperature spoils faster than that kept in the refrigerator. In the refrigerator, the temperature is lower than room temperature and hence the reaction rate is less.
Aerated soft drinks contain dissolved carbon dioxide in a pop bottle (Soda). When the bottle is sealed, the dissolved carbon dioxide (in the form of carbonic acid) and gaseous CO₂ are in equilibrium with each other. When you open the bottle, the gaseous CO₂ can escape, so dissolved CO₂ begins to undissolve back to the gas phase to replace the lost gas. If left open long enough, it goes 'flat' as all CO₂ escapes into the air.

Biogenetic law or Recapitulation theory was given by Ernst Haeckel.
Palaeontology deals with the study of fossils. Leonardo da Vinci is called the Father of Palaeontology.
Biogenesis: It was speculated by Louis Pasteur (1862) that life originates from pre-existing life.
Chemical Evolution of Life: This idea was developed by Oparin (1922) and Haldane (1929).
Jean Baptiste Lamarck (1744-1829) was a French naturalist, well known for his theory of evolution published in 'Philosophie Zoologique' in 1809. It is popularly known as 'Theory of Inheritance of Acquired Characters' or 'Use and Disuse Theory' or Lamarckism.
Mutation and Variation: Two events involved in evolution. Mutation arises due to errors occurring in DNA during replication or exposure to UV rays or chemicals. Mutation leads to variation and brings about changes in a single individual.
Kaspar Maria Von Sternberg is the "Father of Paleobotany" (1761-1838), born in Europe. He established the Bohemian National Museum in Prague.
Birbal Sahni is the "Father of Indian Paleobotany" (1891-1949). He researched the anatomy and morphology of Paleozoic Ferns and fossil plants of the Indian Gondwana Formations.
Living Fossils: Living organisms that are similar in appearance to their fossilized distant ancestors and usually have no close extinct relatives (e.g., Ginkgo biloba).
Radioactive carbon (C¹⁴) dating method was discovered by W.F. Libby (1956).
Thiruvakkarai fossil wood park (Villupuram district, Tamil Nadu): 20 million years ago tree trunks that got buried along the river had their organic matter replaced by silica and became fossilized into solid rocks, retaining annular rings, textures, and node features.
Geologic Time Scale: A system of chronological dating that relates geological rock strata to time to describe the timing and relationships of events in Earth's history.
NASA is developing Mars 2020 astrobiology mission to investigate ancient environments on Mars, surface geological processes, past life, and biosignatures.
Chipko movement: A non-violent agitation in 1973 aimed at protection and conservation of trees originating in Chamoli district of Uttar Pradesh (now Uttarakhand). Villagers hugged trees to prevent cutting. It achieved a major victory in 1980 with a 15-year ban on cutting trees in Himalayan forests.
Jim Corbett National Park was the first national park established in 1936 in Uttarakhand, India. There are 18 biosphere reserves in India (Nilgiris is in Tamil Nadu).
Rathika Ramasamy, a native of Venkatachalapuram village, Theni District, Tamil Nadu, was the first Indian woman to establish an international reputation as a wildlife photographer focusing on birds. Her photobook "The Best of Wildlife Moments" was published in November 2014.
Wildlife Conservation Initiatives in India:
• Project Tiger (1973) and Project Elephant (1992). • Crocodile Conservation Project (1976). • Sea Turtle Conservation Project (1999). • Indian Rhino Vision 2020: To conserve at least 3,000 greater one-horned rhinos in Assam, India by 2020.
India is the third largest consumer of crude oil in the world, after the United States and China.
Case study of Taj Mahal: Located in Agra, UP, built with white marble. Mathura oil refinery emissions of sulphur and nitrogen oxides caused acid precipitation, turning the marble yellow. The Government of India has set up emission standards to protect the monument.
A 100-litre capacity solar water heater can save up to 1500 units of electricity per year.
India has identified six basins for shale gas exploration: Cambay (Gujarat), Assam-Arakan (North East), Gondwana (Central India), Krishna Godavari onshore (East Coast), Cauvery onshore, and Indo-Gangetic basins.
The world's largest and tallest wind turbine is situated in Hawaii. One wind turbine can produce electricity for 300 homes.
Kallanai Dam (Grand Anicut) is the fourth oldest dam in the world, constructed by King Karikala Chola of the Chola Dynasty in the 2nd century A.D. (CE) on River Kaveri, located ~20 km from Tiruchirappalli.
Health Effects of E-Wastes:
• Lead: Damages central and peripheral nervous system; affects brain development in children. • Chromium: Causes asthmatic bronchitis. • Cadmium: Accumulates in kidney and liver; impairs neural development. • Mercury: Causes chronic damage to brain and respiratory system. • Plastics including Polyvinyl Chloride (PVC): Burning produces dioxin causing reproductive and developmental disorders and damages the immune system.
E-waste Composition: Computer components — 66%, Telecommunication components — 12%, Electronic components — 7%, Biomedical components — 5%, Other components — 6%.