NCERT Solutions for Class 7 Science

Welcome to the NCERT Solutions for Class 7 Science. This page offers chapter-wise solutions designed to help students grasp key concepts easily. With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

• Chapter 1 Nutrition in Plants
  • Carbohydrates, proteins, fats, vitamins, minerals and water are the main components of food.
  • The food we eat that gives us energy is known as nutritionary food and we collect nutrition form that food in the form of energy.
  • Plants make their own food in the presence of sunlight called photosynthesis.
  • Plants are called autotrophs because they make their food by themselves or by their own.
  • The organisms who depends on the other organisms for their feeding are known as heterotrophs.
  • Exchange of gases take place through stomata which is present on the surface of the leaves.
  • Stomata are the tiny holes which are covered by the two guard cells which helps in the opening and closing of stomata.
  • Leaves are of green colour because of the presence of pigment chlorophyll.
  • On the basis of mode of nutrition, there are two categories: the plants which gets nutrition by their own food is autotrophic nutrition; and the other one is which gets nutrition by depending on the others for consumption of food is known as heterotrophic nutrition.
  • Insectivores plants are the example of heterotrophic mode of nutrition which feeds on insects.
  • The organisms that feeds on dead and decaying matter are known as saprotrophs and the kind of nutrition they contains is known as saprotrophic nutrition.      

• Chapter 2 Nutrition in Animals
  • Nutrition means intake of food in the body.
  • In animals nutrition include the intake of food, made of intake and its utilization in the body.
  • Digestion is the process in which food is broken into simple substance from the complex one.
  • There are different made of intake of food in animals like chewing, swallowing, sucking etc.
  • In humans digestion is a complex process.
  • Process of digestion including parts Buccal cavity, Oesophagus, Stomach, Small intestine, large intestine, rectum and anus.
  • Buccal cavity have salivary glands which secrete saliva to digest carbohydrate.
  • Liver and pancreas secrete digestive juices to digest the fats and proteins.
  • Intake of food is called ingestion.
  • In mouth, teeth are present. These are 32 in number.
  • Types of teeth incisors, canine, molar and premolar.
  • Starch test is performed by doing starch test.
  • Hydrochloric acid is present in our stomach it kills bacteria.
  • Small intestine is 7.5 meter long and highly coiled structure.
  • Most of the absorption of food occur in small intestine. Small intestine have villi on its walls.
  • Large intestine is about 1.5 meter long.
  • Removal of undigested food through anus called egestion.
  • Ruminants have bacteria in rumen which digest cellulose.
  • Amoeba is a single celled organism it get its food in food vacuole with the help of pseudopodia.

• Chapter 3 Fibre to Fabric
  • Fibres are of two types- Natural fibre and synthetic fibre.
  • The fibre which we obtained from natural are called as natural fibre.
  • Natural fibre is of two types- plant fibre and animal’s fibre.
  • Synthetic fibres are man- made fibres.
  • The outer covering of animals like sheep, goat and rabbit is called fleece.
  • Wool and silk are two animal fibre. We obtained wool from sheep, goat etc.
  • Silk is obtained from cocoon of silk moth.
  • Selective breed of sheep are reared for good quality of wool.
  • The process of fibre into wool include shearing, scouring and sorting again scouring and drying, give colour to wool, rolling.
  • Rearing of silk moth is called sericulture.
  • Life cycle of silk worm is egg - caterpillar or larva - pupa- cocoon.
  • Most common silk moth is mulberry silk moth which gives soft lustrous silk.

• Chapter 4 Heat
  • Temperature is the hotness and coldness of a body.
  • Our sensation tells the hotness of the object.
  • Thermometer is the device on which temperature is measured.
  • A thermometer contains mercury inside it.
  • Temperature can be measured at three scales- Celsius scale, Fahrenheit scale and kelvin scale.
  • Clinical thermometer shows temperature 35 0 C to 42 0 C.
  • A normal body temperature is 37 0 C.
  • Room temperature reading is 25 0 C at the device.
  • Mode of transfer of heat is of three types- Conduction, Convection and Radiation.
  • Conduction may be defined as the transfer of heat from hotter end to the colder end of the object.
  • Convection is the method of transfer of heat by which the whole object is heated.
  • Radiation is the method of transfer of heat through radiation. For example sun.
  • The objects through which heat can pass easily called the conductors of heat.
  • The objects through which heat cannot pass called the insulators of heat.

• Chapter 5 Acids, Bases and Salts
  • Substance are categorized into three- acid, base, salt.
  • Substance having sour taste called as acidic.
  • Substance having bitter taste called as basic.
  • Substance which are neither acidic nor basic called as neutral.
  • Indicators are the substances which shows that the substances are acidic or basic in nature.
  • There are some natural indicators like turmeric, litmus, China rose etc.
  • Litmus changes into blue, when it dissolve in base.
  • When an acid is mixed with base, then it is called neutralization reaction.
  • Salt pH is 7, which is neutral.
  • Neutralization help in our daily life like in acidity ant bite etc.

• Chapter 6 Physical and Chemical Changes
  • The physical appearance are called the physical properties.
  • Changes are the part of our daily life.
  • Changes are of two types- physical and chemical.
  • The changes which we can see physically called physical change. For example melting of ice.
  • The changes which we cannot see are called as chemical change. For example souring of milk, milk to curd.
  • Simply we can say the changes in which new substances is formed called chemical change and in which new substance are not formed called as physical change.
  • Rusting of iron is the example of chemical change.
  • Galvanization is the process by which a layer of zinc on the surface of iron to protect it from rusting.

• Chapter 7 Weather, Climate and Adaptations of Animals to Climate
  • Hotness and coldness of a body called temperature.
  • Temperatures units are Celsius scale Fahrenheit and kelvin.
  • Rainfall is measured by an instrument called rain gauge.
  • The day to day conditions of the atmosphere at a place with respect to the temperature rainfall wind speed and humidity etc. is called weather of that place.
  • Elements of weather on which weather depends are temperature, humidity, wind speed etc.
  • Pressure of water in the atmosphere called as humidity.
  • Climate is the average weather pattern of the place.
  • Deserts have hot and dry climate.
  • Plants and animals change or evolve their habits or their body parts according to the surrounding where they live is called adaptation.
  • In polar region minimum temperature is - 37ºC.
  • Polar bear adapted himself according to their habitat like they have a thick layer of fur, strong sense of small, long sharp curved and sharp claws which help then to walk on ice.
  • According to the surrounding some animals and birds cannot adapt themselves, then they `migrate one place to another according to the weather this is called migration.
  • The tropical rainforest region has generally hot climate because it is located around the equator.
  • The Polar region have different climate conditions like there the sun does not set for six months and far other six months sun does no rise.

• Chapter 8 Winds, Storms and Cyclones
  • Moving air is called wind.
  • Pressure may be defined as the force that a gas or liquid exert when contained inside something.
  • Air exert pressure.
  • As the pressure of air is low, the wind speed is increased whereas if the air pressure is higher than the wind speed decreases.
  • Air moves from the region where the pressure of air is high to the region
  • Air expands in size and occupies more space on heating.
  • The region closer to the equator get maximum heat from run.
  • Wind blow from the North and the South towards the land.
  • A thunderstorm is arises from the heavy rainfall along with the rising air create lightening and sound.
  • A condition of weather in which high speed wind revolving around a low pressure is called cyclone.
  • The center part of a cyclone is called as the eye of the cyclone.
  • A device which is used to measure the speed of wind is called anemometer.
  • The flash of light in the sky that is produced by electricity moving between clouds or from clouds to the ground.
  • Hurricane is a tropical cyclone with winds of 75 miles or greatly that is usually accompanied by rain, thunder and by lightening.
  • A violent storm with a column of rapidly rotating winds having the appearance of dark funnel shaped clouds that reaches from the sky to the ground is called as Tornado.
  • A type of storm system having circular and spiral violent winds called as Typhoon. It eventually occur in western Pacific Ocean.

• Chapter 9 Soil
  • The uppermost layer of the earth is called soil.
  • Soil provide an charge to the plants and supplies nutrients to the plant.
  • The dead and rotting matter in the soil is called humus.
  • Soil is formed by the breaking down of rocks by the action of water, wind and climate this process is called weathering.
  • Soil profile include topsoil or A- horizon, middle layer or B- horizon third layer is C- layer or the last one, this is also called as bed rock.
  • The topmost layer of the soil contain humus and it is fertile.
  • Soil contain greater proportion of big particles are called as sandy soil.
  • The soil which contains greater proportion of the fine particles are called as clayey soil.
  • The mixture of sandy, clayey and other types of soil is called loamy soil.
  • The rate of absorption of water by the soil is called the percolation rate.
  • Erosion is called the removal of upper layer of the soil.
  • Upper layer of soil has better water
  • Different types of soil is better for different crops.
  • Erosion can be prevented by growing more plants.

• Chapter 10 Respiration in Organisms
  • The process of inhaling of oxygen and exhaling of carbon- dioxide is called as breathing.
  • The process of breakdown of food in cells is known as cellular respiration.
  • The organisms who does not need oxygen for respiration are known as anaerobes.
  • Respiration is of two types- aerobic respiration and anaerobic respiration.
  • The respiration which need oxygen or which occur in the presence of oxygen is called aerobic respiration.
  • The respiration which occur in the absence of oxygen is called anaerobic respiration.
  • Muscles respire anaerobically this respiration process occur due to the lack of oxygen.
  • Breathing rate is defined as the number of breathes in one minute.
  • Diaphragm is the muscular sheet which forms a floor for the chest cavity and it protects the delicate organs like heart.
  • Process of respiration is -air from environment- nasal cavity- lungs.
  • Rib cage is a structure of bones in which is connected to backbone.
  • As we inhale air inside, size of diaphragm increases.
  • On exhalation, size of diaphragm decreases.
  • In human body a pair of lungs is present which purify air.
  • For the exchange of gases insects chewing a network of air tubes called trachea.
  • Exchange of gases takes place through skin in earthworm.
  • Unlike humans, fishes have gills with higher blood supply for breathing.
  • Exchange of gases takes place through stomata which are present on the surface of leaves in plants.

• Chapter 11 Transportation in Animals and Plants
  • Movement of food and water from one place to another in animals and plants are called transportation.
  • Blood is the fluid part of the human body which is made up of plasma in which different types of cells are suspended.
  • Blood has mainly 3 types of cells- RBC (Red blood cell), WBC (White blood cell) and platelets.
  • RBC contains a red pigment called haemoglobin.
  • Haemoglobin binds oxygen and transport it from one part to another.
  • WBC make antibodies against any diseases and fight against the disease.
  • Platelets helps in blood clotting.
  • Capillaries are the small thin walled tubes which spread in all over the body.
  • Arteries carry oxygen rich oxygenated or pure blood from the heart to all parts of the body.
  • Veins carry deoxygenated or impure blood from all parts of the body to the heart.
  • Pulse rate is the number of beating of pulse in one minute.
  • Pulmonary artery is the only artery which contains impure blood.
  • All veins carry carbon- dioxide rich blood or impure blood except pulmonary vein.
  • Human heart is 4 chambered- 2 atrium and 2 ventricles.
  • In human heart double circulation of blood occur.
  • Stethoscope is a device to hear the sound of the heart.
  • The process of removal of waste outside from the body is called as excretion.
  • Excretory system involves 2 kidneys, ureter, urinary bladder, urethra, urinary opening etc.
  • Filtration of blood is done by kidneys.
  • Urinary bladder is a muscular bag like structure which collects minimum litre of urine.
  • Dialysis is the process of filtration of blood artificially to purify the blood.
  • In plants, transportation of water and minerals done by xylem tissue.
  • In plants transportation of food is by phloem tissue.
  • A group of cells that perform specialised function in an organisms is called as tissue.
  • Plants loose lot of water through stomata which are present in leaves by transpiration process.

• Chapter 12 Reproduction in Plants
  • The parents give birth to their young ones which are similar to them is called reproduction.
  • Reproduction is of types. Vegetative, sexual and asexual.
  • Vegetative is the part of asexual reproduction.
  • Root, stem, leaves are the vegetative parts of the plants.
  • The reproduction in which only parent are involved is known as asexual reproduction.
  • In plants reproduction occur in flower. Flower has reproductive parts.
  • A small outgrowth appear on the plant is called as budding.
  • Asexual reproduction occur in many ways like budding, fragmentation, spare formation etc.
  • The reproduction in which part of the plant in divided into two is known as fragmentation.
  • Spares are tiny asexual reproductive bodies.
  • The reproduction which occur due to the formation of spares known as spare formation method of asexual reproduction.
  • Unisexual flowers are those in which only are reproductive part is present either male or female.
  • Bisexual flowers are those in which both male and female reproductive parts are present.
  • Stamen is the male reproductive part of the plant which contain Anther and filament.
  • The male and female reproductive cells are called gamete.
  • Male gamete is produced by pollen grain which is inside the anther.
  • The female gamete or the egg is formed in an ovule.
  • The process of fusion of male and female gamete is called fertilization.
  • Hypha is a long thread or branch like structure which forms the body of the fungus.
  • Ovule contains egg or female gametes which is the part of the ovary.
  • When a pollen grain lands on the stigma of a flower, it grains in a tube, this tube is called as pollen tube.
  • The transfer of pollen from the anther to the stigma of a flower is called pollination.
  • Movement or transport of seeds away from the plant by means like wind, air and water is called seed dispersal.
  • By the fusion of male and female gamete a cell is formed known as zygote.
  • After development of zygote, embryo is formed.

• Chapter 13 Motion and Time
  • When object is moving, then we say that it is in motion.
  • Motion is of different types- Rectilinear motion, oscillatory motion, circulatory motion and vibratory motion etc.
  • Speed is the distance covered by the object in a unit time.
  • When an object is moving along a straight line with constant speed is known as uniform motion.
  • When an object is moving along a straight line with change in speed is known as non- uniform motion.
  • A motion which occur in the same internal of time is called periodic motion. Example- pendulum.
  • A metallic round shaped of the pendulum is called as bob.
  • Unit of time is second.
  • Unit of speed is ms^-1 or m/s.
  • Measurement of speed is record on speedometer.
  • Odometer is a device which measure the distance covered by the vehicle.
  • A graphical display of data using bars of different heights is called as graph.
  • Visual representation of the given data called as graph.
  • Time taken by the pendulum to complete one oscillation is called its time period.
  • Graph shows a straight line, which it make between distance and time.
  • Shortest distance covered by the body or object is known as displacement.

• Chapter 14 Electric Current and Its Effects
• Chapter 15 Light
• Chapter 16 Water: A Precious Resource
  • Water is essential for survival.
  • Earth appears blue from space due to the presence of waste.
  • There are different source of water are like lake, pond, sea, well, rivers and oceans.
  • Water generally found in 3 states- solid, liquid and gas.
  • When ground water evaporates then at higher level these vapours condense and form clouds. Clouds have tiny drops inside them. Then rain occur. This is the water cycle.
  • The process of seeping of water into the ground is called infiltration.
  • At some places, ground water is stored between the layers of hard rock below the water table is known as aquifer.
  • The lowering in the level of water table is known as depletion of water table.
  • Rain water is used to recharge the ground water.
  • Collection of rain-water is called rain harvesting or water harvesting.
  • The method by which plants take water by drip system is called drip irrigation.
  • Save water, save life.

• Chapter 17 Forests: Our Lifeline
  • Forest is a place where different types of plants and animals lives.
  • Different types of food is obtained from the plants.
  • An animal or a plant where they live called their habitat.
  • Climbs have weak stem, with the support of other plant, they climb up on them.
  • Creepers spread all over the ground.
  • Micro- organisms decompose the organic waste and convert them into compost. This is called as humus.
  • The micro- organisms which decompose dead and decaying organic matter are known as decomposers.
  • Animals and plants help each other by exchange of gases.
  • Forests are also known as the lungs.
  • The branches of tall trees look like a roof over the other plants in forests is called canopy.
  • The skin part of trees with branches is known as the crown.
  • Cutting down of forests is called deforestation.
  • The process of getting back a full organism from its body parts is called regeneration.
  • Removal of top layer of the soil by water or wind is known as soil erosion.
  • The layer of vegetation grows under the shade of a canopy, then the forest is known as understory.

• Chapter 18 Wastewater Story
  • Water is essential for the survival of life.
  • Used water is called as waste water.
  • Waste water comes from home usually like from sink, showers, toilets etc.
  • The process of removing impurities or pollutants from water is called as cleaning of water.
  • Wastewater treatment is commonly called as sewage treatment.
  • Sewage is a mixture of solid and liquid waste which comes from home, industries, hospitals etc.
  • Different types of impurities present in water like organic, inorganic, nutrients, bacteria and other microbes.
  • Sewer is the network of big and small pipes, farming the sewerage.
  • The process by which air is mixed with a liquid. Aeration is done during sewage water treatment to provide growth of aerobic bacteria as they consume waste materials like humans waste, food waste etc. is called as aeration.
  • The bacteria which need oxygen to survive are known as aerobic bacteria.
  • Anaerobic bacteria are those who don’t need oxygen to survive.
  • Biogas is produced when sludge is decomposed by the anaerobic bacteria.
  • A polluting or poisonous substance that makes something impure.
  • Keeping our surrounding clean known as sanitation.
  • During waste water treatment the solid waste which settle down in the tank known as sludge.