Chapter-wise NCERT Solutions Of Class 7 Science

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.