Chapter - 1 : Nutrition in Plants Let’S Revise

Chapter - 1 : Nutrition In Plants Let’s Revise

 The mode of taking food by an organism and its utilisation by the body is called nutrition.  Carbohydrates, fats, proteins, vitamins and minerals are the components of food and are called nutrients.  The mode of nutrition in which organisms make their food themselves from simple substances is called autotrophic nutrition.  The mode of nutrition in which organisms depend on others for their food is called heterotrophic nutrition.  The process in which green plants make their food in the presence of sunlight using carbon dioxide and water is called photosynthesis.  The bodies of living organisms are made of tiny units called cells.  The leaves of plants have a green pigment called chlorophyll which is one of the essential component of photosynthesis.  Leaves are food factories of plant. The synthesis of food in plants occurs in leaves.  Water and minerals present in the soil are absorbed by the roots and transported to the leaves.  Carbohydrate formed during photosynthesis is stored in the form of starch.  Proteins are nitrogenous substances.  The organisms which live on or in other animals are called the parasites.  The organisms from which parasites take their food are called host.  The insect eating plants are called insectivorous plants.

Know the Terms

 Saprotrophic Nutrition : The mode of nutrition in which the organism decomposes the dead and decaying organic materials of the body by secreting enzymes and then absorbs the nutrients in solution.  Saprotroph : Plants which use saprotrophic mode of nutrition.  Some organisms live together and share shelter and nutrients. This is called symbiotic relationship.  Lichens are the most common example of symbiotic relationship in which an algae and a fungus live together.  Stomata : There are tiny pores present on the surface of the leaves for exchange of gases from atmosphere. Each pore is called stoma (stoma-singular form) and is surrounded by Guard cells.  Food factory : Leaves are called the food factory of the plants because the food is prepared in the leaves.  Rhizobium : Rhizobium is a bacterium which lives on root nodules of pulses and other leguminous plants. It provides nitrogen to plants by the process known as ‘nitrogen fixation‘.  Legumes : The plants related to pulses and having pods are called legumes like methi, urad.  Iodine test : This test is performed to detect the formation of starch in the leaves. The starch gives blue - black colour with iodine.  Fertilizers : The inorganic chemical compounds prepared in the industries and rich in the nutrients are called fertilizers. 2 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Flowchart

Nutrition

Autotrophic Heterotrophic

Process of making food Parasitic Saprophytic Photosynthesis

Chlorophyll

Sunlight

Insectivorous Symbiosis

 Chapter - 2 : Nutrition In Animals Let’s Revise  Animals are heterotrophic in their mode of nutrition because they cannot prepare their own food.  Most of the animals take food in the form of solids and this process of nutrition is called holozoic nutrition.  Holozoic mode of nutrition has the following steps : (a) Ingestion (b) Digestion (c) Absorption (d) Assimilation (e) Egestion  The alimentary canal of humans can be divided into following parts : (a) Buccal cavity (b) Oesophagus (food pipe) (c) Stomach (d) Small intestine (e) Large intestine (f) Anus.  The undigested and unabsorbed residues are expelled out of the body as faeces through the anus.  Amoeba ingests its food with the help of its false feet or pseudopodia. The food is digested in the food vacuole. Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 3 Ectoplasm Endoplasm Mitochondria Nucleus Crystals

Food vacuole

Advancing pseudopod Contractile vacuole Fig. Amoeba

Know the Terms  Buccal cavity : The cavity of mouth, with all its internal parts like cheeks, teeth, tongue and salivary glands is called buccal cavity.  Cellulose : A type of carbohydrate. Many animals including human cannot digest cellulose.  Glycerol : It is one of the constituents of fat. It combines with fatty acid to from fats.  Fatty Acids : One of the main constituents of fats.  Ingestion : Process of taking food into the body.  Digestion : The breakdown of complex components of food (which cannot be utilised by our body) into simpler and absorbable substances is called digestion.  Absorption : The passage of digested food into the blood vessels is called absorption of food. This process takes place in the small intestine in case of human beings.  Assimilation : The process in which the absorbed food is used for producing energy and growth is called assimilation.  Egestion : The removal of undigested and unabsorbed food material, called faecal matter through the anus from time to time is called egestion. Arrangement of different types of teeth :

Fig. : Types of Teeth Types of teeth with functions :

Number in each Types of Teeth Structure Function half of the jaw Incisors (Front teeth) 1 Have flat, sharp edges Cutting and biting the food. Canines 2 Sharp and conical Tearing and piercing Premolars 2 Bicuspids and have one or Crushing and grinding two roots Molars 3 Four or five cusps, have more Crushing, grinding and mastication than one root 4 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Number and types of teeth in man Types of Teeth Milk teeth Permanent teeth Incisor 4 4 Canine 8 8 Premolar 8 8 Molar 0 12 Total number of teeth 20 32  Tooth decay : After eating food, especially sweets, chocolates, cold drink and other sugars, if mouth is not washed properly, then some leftover food and sugars remain attached to teeth. The harmful bacteria break down the sugars and release acids. The acids gradually damage the teeth. This is called tooth decay which may lead to toothache and even loss of tooth.  Amazing fact Starfish feeds on animals covered by hard shells of calcium carbonate.

Fig. : Starfish  ORS (Oral Rehydration Solution) : It is prepared by dissolving a pinch of salt and sugar in boiled and cooled water. It prevents dehydration of the body due to diarrhoea and vomiting. Flowchart

Nutrition in Animals

Classification Based Utilisation/Digestion on Eating Habits in Body Digestion is the breakdown of complex components of food Herbivorous into simpler substances.

In Humans

Carnivorous

Omnivorous

Parasites In Grass-eating Animals

In Amoeba Scavengers Nutrition in Animals

Classification Based Utilisation/Digestion on Eating Habits in Body Digestion is the breakdown of complex components of food Herbivorous into simpler substances.

In Humans

Carnivorous

Omnivorous

Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 5

Parasites In Grass-eating Animals

In Amoeba Scavengers

 Chapter - 3 : Fibre to Fabric

Let’s Revise

 The fibres obtained from animals are called animal fibres. Example, wool and silk.  Wool is obtained from the fleece (hairy growth) of animals such as goat, sheep, yak, alpaca, llama, lamb.  The wool yielding animals have a thick coat of hair which traps a lot of air. Being poor conductor of heat, hairs keep these animals warm.  The fine soft hair fibres are used for making wool. Some Indian Breeds of Sheep S. No. Name of breed Quality of wool State where found 1. Lohi Good quality wool Rajasthan, Punjab 2. Rampur bushair Brown fleece Uttar Pradesh, Himachal Pradesh 3. Nali Carpet wool Rajasthan, Haryana, Punjab 4. Bakharwal For woollen shawls Jammu and Kashmir 5. Marwari Coarse wool Gujarat 6. Patanwadi For hosiery Gujarat

 Processing fibres into wool involves the following steps :  The fleece of the sheep along with a thin layer of skin is removed by machines. This process is called shearing.  The sheared hair is thoroughly washed in tanks to remove grease, dust and dirt. This process is called scouring.  Clean hairy skin is sent to the factory where hair of different textures are sorted (separated). This is called sorting.  The small fluffy fibres, called burrs, are picked out from the hair.  The natural fleece of sheep and goats is black, white or brown. So, the fibres are dyed in various colours.  The fibres are straightened, combed and rolled into yarn. The shorter fibres are spun and woven into woollen clothes. The longer fibres are made into wool for sweaters.  Silk fibre is obtained from the cocoon of the silk moth.  The breeding and management of silkworms for production of silk is called sericulture. 6 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Know the Terms  Selective breeding : Some breeds of sheep possess only fine under - hair. The process of selecting parents is termed as selective breeding.  Silk : It is a natural protein fibre, some forms of which can be woven into textiles.  Sericulture : The breeding and management of silkworms for the production of silk is known as sericulture. Life cycle of silk moth : There are four stages in the development of silk moth : Eggs → Caterpillars → Pupa → Silk moth Silkworm (Adult) (larva)  Discovery of silk : Silk is supposed to be discovered in China. Accidentally, a cocoon dropped into the cup of tea of empress silung-chi, and a tangle of delicate threads separated from the cocoon. Silk industry began in China and was left a closely guarded secret for hundreds of years. Later on, traders and travellers introduced silk to other countries. The route they travelled is still called the ‘Silk route’. Flowchart

Fibres Long, fine, continuous threads or filaments are obtained from plants and animals.

Animal Fibres Plant Fibres

Silk Wool

Sources of Silk Processing of Silk Fibre Sources of Wool

Wool is obtained from sheep. yak (Tibet and Ladakh), Angora goat, goat, camels, llama andAlpaca, (SouthAmerica)

Obtaining Wool Fibre Obtaining Silk Fibre Shearing : Fleece of the sheep along with a thin layer of skin is removed from its body.

Processing of Wool Fibre

 Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 7 Chapter - 4 : Heat Let’s Revise  A reliable measure of the hotness of an object is its temperature.  Temperature is measured by a device called thermometer.  Clinical thermometer is used for measuring our body temperature.  A clinical thermometer reads our temperature from 35°C to 42°C.  The normal temperature of a human body is 37°C.  In order to measure the temperature of other objects, we make use of Laboratory thermometer.  The range of laboratory thermometer is from– 10°C to 110°C.  The heat flows from a body at a higher temperature to a body at a lower temperature. Heat can flow from one object to another in three different ways, namely, conduction, convection and radiation.  In solids, generally, the heat is transferred by conduction. In liquids and gases, the heat is transferred by convection. No medium is required for the transfer of heat by radiation.  Heat always flows from hotter objects to colder objects.  The materials which allow heat to easily pass through them are conductors of heat.  The materials which do not allow heat to pass through them easily are called the insulators of heat.  When heat falls on some object, then some part of the heat gets reflected, some portion gets absorbed and some part gets transmitted.  Dark coloured objects absorb radiation better than the light coloured objects. That is the reason, we feel more comfortable in light coloured clothes during the summer.  Woollen clothes keep us warm during winter. It is because wool is a poor conductor of heat and it has air trapped in between the fibres. Know the Terms  Celsius scale : The scale in which the temperature is represented in °C is called celsius scale.  Conduction : The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.  Conductor : Those materials which allow heat to pass through them easily are called the conductors of heat.  Convection : The process of heat-transfer in a liquid by the movement of liquid is called convection.  Insulator : Those substances which do not conduct heat well are called insulators.  Land Breeze : After sunset, the air above the sea is warmer which makes the air rise and the cooler air above the land, moves out towards the sea. This is called ‘Land Breeze’.  Radiation : Radiation is the process by which heat travels without the help of a material medium.  Sea Breeze : During the day the air in contact with the land becomes hot and rises. Then the cooler air above the sea rushes in towards the land to occupy its space. This set-up is known as sea breeze.  Temperature : The temperature of a substance is the measure of degree of hotness of the substance.  Thermometer : The instrument which is used to measure the temperature is called thermometer. Flowchart 8 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII

 Chapter - 5 : Acids, Bases and Salts Let’s Revise  Acids are sour in taste. Bases are bitter in taste and soapy to touch.  Acid turns blue litmus red, while bases turn red litmus blue.  Substances which are neither acidic nor basic, are said to be neutral.  Solutions of the substances that show different colours in acidic, basic and neutral mediums are called indicators.  Litmus and turmeric are natural indicators.  An acid and a base neutralize each other to form a salt. This is known as neutralisation.  Heat always evolves in neutralisation, salt and water are also formed in neutralisation.  We take antacid in the form of ‘Milk of Magnesia’ to remove the acidity in stomach.  Since ants have formic acid in their sting, that is why stinging of ants becomes painful.  Since sting of an ant contains formic acid, its pain can be relieved by rubbing moist baking soda which neutralises the formic acid.  The acidity in the soil can be eliminated by adding quicklime or slaked line. Know the Terms  Acid : Acids are sour in taste.  Acidic : An acidic substance contains an acid.  Base : Bases are bitter in taste and soapy to touch.  Basic : A basic substance contains a base.  Indicator : An indicator is a substance that gives different colours in acidic and basic media.  Neutral : A neutral substance has neither acidic nor basic character.  Neutralization : In a neutralization reaction, an acid reacts with a base to form salt and water.  Salt : The product formed (a new substance) by neutralisation reaction between an acid and a base is called salt.  Acid Rain : The rain becomes acidic when carbon dioxide, sulphur dioxide and nitrogen dioxide present in the atmosphere, dissolve in rain drops. These gases when dissolved in rain drops form carbonic acid, sulphuric acid and nitric acid respectively. Acid rain may cause damage to historical monuments, plants and animals. Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 9  Ant sting : The ant sting contains formic acid which when injected into the skin causes pain and irritation. By applying moist baking soda the effect of the sting can be neutralised.  Litmus paper : When indicators are found in the form of strips of paper, then it is known as litmus paper. Red litmus paper and blue litmus paper are two types of litmus paper. The acids change blue litmus paper into red colour and the bases change red litmus paper into blue colour.  Common acids : Hydrochloric acid, Nitric acid, sulphuric acid etc.  Common bases : Sodium hydroxide, potassium hydroxide, ammonium hydroxide.  Role of hydrochloric acid in digestion : Our stomach contains hydrochloric acid which helps in digestion. Flowchart

 Chapter - 6 : Physical and Chemical Changes Let’s Revise  A change in which a substance undergoes a change in its physical properties is known as Physical change.  In a physical change, no new substance is formed at all.  A change in which one or more new substances are formed, is called chemical change.  New substances are formed in a chemical change.  Chemical change is also called a chemical reaction.  In a chemical change, heat is either evolved or absorbed. 10 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII  In a chemical change, light and sound are also evolved.  While a physical change is reversible, a chemical change is irreversible.  Rusting of iron, photosynthesis and digestion of food are the examples of chemical changes.  In order to protect iron from rusting, a coating of zinc is deposited on its surface. This process is called the galvanization of iron.  Stainless steel is manufactured by mixing iron with carbon and metals like chromium, nickel and manganese.  Stainless steel never gets corroded. Some substances can be obtained in pure state from their solutions by crystallisation.

Know the Terms  Chemical Change : A change in which one or more new substances with different properties are formed is called chemical change.  Physical Properties : Properties such as shape, size, colour and state of a substance are called physical properties.  Physical Change : Change in which only physical properties of any substance change and no new substance is formed is called a physical change. A physical change is mostly reversible and does not form a new substance.  Some examples of physical changes and chemical changes in our daily life are : Physical Change Chemical Change 1. Kneading dough from flour. 1. Making chapatis from dough. 2. Cutting vegetables into small pieces. 2. Cooking vegetables. 3. Heating an iron object. 3. Rusting of iron.  Rusting : If a piece of iron is left in the open for some time, if acquires a film of brownish substance. This substance is called rust. The process by which rust is formed on an iron object is called rusting. For rusting, the presence of moisture (or water vapour) and oxygen is essential.  The process of rusting can be represented by the following equation : Iron (Fe) + Oxygen (O2 from air) + Moisture (H2O) → Rust (Iron oxide Fe2O3) Rust of iron is chemically different from iron.  Galvanisation : The process of depositing a layer of zinc on iron is known as galvanisation. The iron pipes are galvanised to prevent rusting.  Crystallisation : Large crystals of pure substances can be formed from their solutions, especially from their concentrated solutions. The process of formation of crystals is called crystallisation. Crystallisation is an example of a physical change. Flowchart

Changes Types

Physical Change Chemical Change

Chemical Reactions in Everyday Life

Decay of Cooking of Decay of Inorganic Substances Food Organic Substances

Prevention of Rusting

· Painting Crystallisation Oiling and greasing · · It is used to obtainasubstance in the pure form. · Plastic coating · Crystal : A solid structure with flat sides. · Chromium plating · Galvanising · Alloying Changes Types

Physical Change Chemical Change

Chemical Reactions in Everyday Life

Decay of Cooking of Decay of Inorganic Substances Food Organic Substances

Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 11

Prevention of Rusting

 Chapter - 7 : Weather, Climate and Adaptations of Animals to Climate Let’s Revise  Day to day conditions in the atmosphere around one place in relation to the temperature, wind speed, rainfall etc. are referred to as the weather of that place.  Normally weather is not the same on any two days, it keeps on changing week after week.  The maximum temperature of a particular day occurs usually in the afternoon, while the minimum temperature is recorded in the early morning.  The time of sunrise and sunset also change according to the season.  All changes in whether are brought about by the sun.  Climate of a country or place is the average weather pattern taken over a long period e.g., 25 years.  The tropical and polar regions are the two regions of the earth which have severe climatic conditions.  Animals are adapted according to the conditions in which they live.  Polar regions are extremely cold all the year round. The sun does not set for six months in a year, in other six months it does not rise.  In polar regions, animals are adapted to the freezing cold climate as they have some special characteristics like white fur, sharp senses of smell, a layer of fat under the skin and also large wide paws for walking and swimming.  Migration is another way of escaping biting cold conditions.

Know the Terms  Adaptation : Features and habits that help animals to adapt to their surroundings are a result of the process of evolution.  Climate : The average weather pattern taken over a long time, say 25 years, is called the climate of the place.  Polar Region : The polar regions present an extreme climate. These regions are covered with snow.  Rain Gauge : Rainfall is measured by an instrument called the rain gauge.  Tropical Region : The tropical region has generally a hot climate because of its location around the equator.  Weather : The day-to-day condition of the atmosphere at a place with respect to the temperature, humidity, rainfall, wind-speed etc., is called the weather of that place. 12 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Flowchart

Weather

Climate Chemical Change

areas.

Adaptations to Climate

The features and habits that help animals to live in a habitat are called adaptations.

Polar Regions Tropical Rainforest Deserts

Polar Bears Lion-tailed Macaque Camels

Penguins Elephant

 Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 13 Chapter - 8 : Winds, Storms and Cyclones Let’s Revise  Pressure all around us is exerted by air.  Upon heating, air expands, it contracts upon cooling.  Warm air rises up, whereas relatively cool air is inclined to sink towards the earth’s surface.  As warm air rises up, pressure at that particular spot drops down, so the cooler air moves in to that spot.  Wind is another name of ‘moving air.’  Imbalanced heating on the earth is the major cause of wind movements.  Winds carrying water vapour cause rain.  Cyclones are caused by the differences in air pressure and high speed winds.  Advanced technologies like radars enable us to monitor cyclones without much difficulty.  Self-defence is the best way to protect ourselves. Hence it is strongly advisable to plan in advance and be fully prepared to face all the eventualities of any approaching cyclone.

Know the Terms  Anemometer : The instrument used for measuring the speed of wind is called Anemometer.  Cyclone : A cyclone is a storm that develops over the sea.  Hurricane : In American continent, the cyclone is referred to as ‘Hurricane.’  Lightning : The swift movement of the falling water droplets together with the rising air causes lightning.  Low Pressure : Increased wind speed is accompanied by a low pressure.  Monsoon Winds : The Monsoon winds carry water, so it rains.  Pressure : Air exerts pressure.  Thunderstorms : Thunderstorms occur when a cold current of air meets with a rising column of hot air.  Tornado : A tornado is a funnel shaped violently rotating column of air extending from the earth’s surface to a thunder cloud.  Typhoon : A cyclone in Philippines and Japan is known as typhoon.  Wind flow pattern : Due to the uneven heating of the earth, wind flow patterns develop. Flowchart

Air

Properties of Air Wind

Wind Currents Thunderstorms

Storm with thunder and lightning along with rain.

Cyclones Tornadoes Precautionary Measures Storms that form very suddenly on land and look like a twisting funnel of air.

Effective Safety Protection Measures from Tornado Air

Properties of Air Wind

Wind Currents Thunderstorms

Storm with thunder and lightning along with rain.

14 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII

Cyclones Tornadoes Precautionary Measures Storms that form very suddenly on land and look like a twisting funnel of air.

Effective Safety Protection Measures from Tornado

 Chapter - 9 : Soil Let’s Revise  Soil is very vital to life on our planet.  Soil profile is a section through various layers of the soil. Different layers are referred to as horizons.  Soil falls into three different types : sandy, loamy and clayey.  Rate of percolation of water varies from one type of soil to another. In sandy soil, it is the highest, but least in the clayey soil.  Different types of soil enable us to cultivate a variety of crops. Loam and clay are most favourable for the growth of wheat, paddy and gram. Sandy loamy soil is most suitable for growing cotton.  Soil contains some water within it, that is mentioned as ‘soil moisture’. The capacity of a soil to hold water has significance in various crops.  Pots, toys and statues are made out of clayey soil.

Know the Terms  Clayey Soil : If the proportion of fine particles is relatively higher, then it is called clayey soil.  Humus : The rotting dead matter in the soil is called humus.  Loamy : If the amount of large and fine particles is about the same, then the soil is called loamy.  Sandy Soil : If soil contains greater proportion of big particles, it is called sandy soil.  Soil : The mixture of rock particles and humus is called the soil.  Soil Profile : A vertical section through different layers of the soil is called the soil profile.

Fig. Soil profile Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 15 Flowchart

 16 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Chapter - 10 : Respiration in Organisms Let’s Revise  Respiration is highly important for the life of all living organisms.  The oxygen inhaled by us, helps to breakdown glucose into water and carbon dioxide. In this process, energy is released.  The breakdown of glucose takes place in the cells of an organism (cellular respiration).  When the food is broken down by using oxygen, it is mentioned as ‘Aerobic respiration’. If the breakdown takes place independent of oxygen, then it is referred to as anaerobic respiration.  During heavy exercise, when the supply of oxygen to our muscles is less than enough, food breakdown occurs through anaerobic respiration.  Breathing is one part of the process of respiration during which an organism takes in the oxygen rich air and releases air rich in carbon dioxide. The respiratory organs for the interchange of gases vary from one organism to another.  During inhalation, our lungs expand first and then return to their original position as the air passes out during exhalation.  The breathing rate is raised by increased physical activity.  Among animals like cat, cow, dog and buffalo, breathing process and respiratory organs are like those in us.  Amongst earthworms, the exchange of gases takes place through moist skin. In a fish, it occurs through gills, with insects, it is through the trachea.  In a plant, the roots inhale air found in the soil. Leaves possess small little pores known as ‘stomata’ through which they exchange gases. The breakdown of glucose among the plant cells is just like all other living beings.

Know the Terms  Aerobic respiration : When breakdown of glucose occurs with the use of oxygen, it is called aerobic respiration.  Anaerobic respiration : Food can also be broken down, without using oxygen. This is called anaerobic respiration.  Breathing rate : The number of times a person breathes in a minute is termed as the breathing rate.  Diaphragm : A large, muscular sheet called diaphragm forms the floor of chest cavity.  Gills : Gills in fish help them to use oxygen dissolved in water.  Exhalation : Giving out of air rich in carbon dioxide is known as exhalation.  Inhalation : Taking in of air rich in oxygen into the body is called inhalation.  Tracheae : Insects have a network of air tubes called tracheae for exchange. Flow Chart RESPIRATION

External Respiration Internal Respiration Processinwhich oxygen is taken Process in which food is brokendown insidethe body and carbondioxideis in body cells throughvarious chemical given out. reactions. It is also calledbreathing.

RespirationinPlants Respirationin Animals Respirationin Humans Leaves have pores calledStomatafor Inhaled air passes throughnostrils into gaseous exchange by diffusion. nasal cavity and thenintolungs through Stems have openings calledlenticles windpipe. for gaseous exchange by diffusion. Duringinhalation, ribs move up and Roots haveStomatal poresfor gaseous outwards,and diaphragm moves down. exchange of oxygen dissolvedinsoil In thelungs,the windpipebranchesout into water. bronchiand evensmallerbronchioles, which endin air sacs called alveoli. Here,oxygen from the airdiffuses into blood capillaries and carbon dioxidediffuses out into the alveoli. Duringexhalation, ribsmove down and inwards anddiaphragm moves up.

Earthworm Insects Fish Frogs Gaseous exchange Gaseous exchange Fish absorbs dissolved Exchange of gasesin occurs through its skin. takes place throughthe oxygen fromthe water frogtakes place through Thin, moist skin is entire body surface by by meansofgills. its thin, moist and smooth suppliedwith a diffusion. Water flowsacross the skin, wheninwater. network of capillaries. They haveelaborate gills, theoxygeninit Frogs also have lungs These absorboxygen systemofbranching gets diffusedinto the forrespiration on land. fromthe atmosphere tubes called tracheae. blood circulatingingills. and get rid of carbon Carbon dioxideinthe dioxide fromthe body bloodstreamdiffuses into the water andiscarried outthroughagap betweenthe fish's body andthe gill cover.

Respirationin Animals AnaerobicRespiration Food molecules arecombinedwith oxygen and get oxidised Food molecules are broken down without usingoxygenalongwith insidecellintocarbon dioxide and water along with energy. release of energy. Enzymes Yeast Glucose+Oxygen Carbon dioxide+Water + Energy Glucose Ethyl alcohol +Carbon dioxide+Energy

Glucose Lactic acid+Energy (in muscles) RESPIRATION

Glucose Lactic acid+Energy (in muscles)

 Chapter - 11 : Transportation in Animals and Plants

Let’s Revise  Amongst most animals the blood that circulates in the body distributes food and oxygen to different cells in the body. It also conveys waste products to different parts of the body for excretion.  Circulatory system is made up of the heart and blood vessels.  Among humans, blood flows through arteries and veins. Here the heart acts as a pumping organ.  Blood is made up of plasma, RBC, WBC and platelets. The redness in blood is because of the presence of a red pigment called ‘Haemoglobin’.  Human heart beats at the rate of nearly 70-80 times per minute in a grown-up being. We refer to this as ‘Heart Rate’.  The function of arteries is to carry blood from heart to other parts of the body.  Veins carry blood from all parts of the body back to the heart.  Expulsion of waste products from the body is known as excretion.  Human excretory system is made up of two kidneys, two ureters, a urethra and a urinary bladder.  Urea and salts are expelled from the body with water as sweat.  Fish excrete waste matter which gets directly dissolved in water.  Birds, insects and lizard excrete uric acid in the semi-solid form.  Water and mineral nutrients are assimilated by roots of the soil.  Nutrients are carried along with water to the whole plant through the vascular tissue named ‘xylem’.  The vascular tissue for transporting the food to other parts of the plant is called phloem.  Through stomata, plenty of water is lost by plants during transpiration.  Transpiration builds up a force which draws up water absorbed by the roots from the soil, to reach the stem and leaves. Know the Terms  Arteries : Arteries carry oxygen-rich blood from the heart to all parts of the body.  Blood : Blood is the fluid which flows in blood vessels.  Excretion and excretory system : The process of removal of wastes produced in the cells of the living organisms is called excretion. The parts involved in excretion form the excretory system.  Heart : The heart is an organ which beats continuously to act as a pump for the transport of blood.  Haemoglobin : One type of cells are the red blood cells (RBC) which contain red pigment called haemoglobin.  Plasma : The fluid part of the blood is called plasma.  Platelets : The clot is formed because of the presence of another type of cells in the blood, called platelets.  Veins : Veins are the vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart.  White Blood Cells : The blood also has white blood cells (WBC) which fight against germs that may enter our body.  Xylem : The vascular tissue for the transport of water and nutrients in the plant is called the xylem. 18 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Flowchart

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Heartbeat

Excretory

bloo

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thin

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 Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 19 Chapter - 12 : Reproduction in Plants

Let’s Revise

 All living organisms, multiply and reproduce their own species.  There are different methods for a sexual reproduction like budding, spore formation, vegetative propagation and fragmentation.  In sexual reproduction, the fusion of male and female gametes is involved.  In vegetative propagation, new plants are produced from various vegetative parts like roots, stems and leaves.  Flower is the reproductive part of the plant.  A flower can be unisexual with either the male or female reproductive parts.  A bisexual flower possesses both the female and the male reproductive parts.  The male gametes occur inside the pollen grains and the female gametes are found in an ovule.  Pollination is the process of transfer of pollen grains from the anther of one flower to the stigma of the same or another flower.  Pollination falls into two types : Self pollination and cross pollination. In self-pollination, pollen grains get transferred from the anther to the stigma of the same flower of the same type.

 Pollination occurs among plants by means of insects, water and wind. Anther  Fusion of male and female gametes is called fertilization.  Fertilized egg is called zygote. Zygote develops into an embryo.  Fruit is the mature ovary whereas ovule develops into a seed that contains the developing embryo. Filament  Wind, water and animals help the dispersion of the seed.  Dispersal of the seeds is an aid to the plants in three ways : (i) Prevention of congestion, (ii) Less of competition for sunlight, water(a) Stamenand minerals, (iii) Attack of new habitats.

Stigma

Style Anther Ovule

Ovary

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(a) Stamen (b) Pistil Reproductive Parts Reproductive Parts Stigma Know the Terms Style

 Asexual reproduction : In asexual reproduction,Ovule plants can give rise to new plants without seeds.  Bisexual flowers : The flowers which contain both stamens and pistil are called bisexual flowers. Ovary  Embryo : The zygote develops into an embryo.  Fertilization : The process of fusion of male and female gametes (to form a zygote) is called fertilization.  Flowers : Flowers are the reproductive parts of a plant.

 Pistil : Pistil is the female reproductive(b) part. Pistil  Pollination : The transfer of pollenReproductive from Pthearts anther to the stigma of a flower is called pollination.  Reproduction : The production of new individuals from their parents is known as reproduction.  Sexual reproduction : In sexual reproduction, new plants are obtained from seeds.  Stamen : The stamens are the male reproductive parts.  Unisexual flowers : The flowers which contain either only the pistil or only the stamens are called unisexual flowers. 20 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Flowchart

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 Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 21 Chapter - 13 : Motion and Time Let’s Revise  The distance moved by an object in a unit time is called its speed.  Speed of objects helps us to decide which one is moving faster than the other.  The speed of an object is the distance travelled divided by the time taken to cover that distance. Its basic unit is metre per second (m/s).  Periodic events are used for the measurement of time. Periodic motion of a pendulum has been used to make clocks and watches.  Motion of objects can be presented in pictorial form by their distance-time graphs.  The distance-time graph for the motion of an object moving with a constant speed forms a straight line.

Know the Terms  Metre : The standard unit of length.  Oscillation : Periodic movement of an object is called oscillation.  Pendulum : A weight hung from a string. Total distance covered  Speed : Speed = Total time taken  Time period : The time taken by the pendulum to complete one oscillation is called its time period. Flowchart

Motion

Types of Motion Speed Distance-Time Graph

Uniform Motion Totaldistancecovered

Totaltimetaken

Measurement of Speed

Non-uniform Motion If the speed of an object moving along a straight line keeps changing, its motion is said to be non- Measurement of Time uniform.

Simple Pendulum

 22 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Chapter - 14 : Electric Current and its Effects Let’s Revise

 Common electric components are represented by symbols. Using these symbols, electric circuit can be expressed diagrammatically.  An electric circuit mainly consists of (i) a source of electric energy (dry cell), (ii) a device that uses the current (bulb), (iii) the connecting wires (conductors) and (iv) a device to open or close the circuit (switch). Symbols for some electric components

S. No. Electric Component Symbol

 To increase the current, two or more cells are connected. Such a combination is called a battery. For this purpose, positive terminal of the cell is connected to the negative terminal of another cell.  Electric circuit can be open or closed. In a closed circuit, current flows whereas no current flows through an open circuit.  When an electric current flows through a wire, the wire gets heated. It is called heating effect of current. It depends on the nature of wire, length, thickness and strength of electric current. Nichrome wire gets red hot on passing current through it. These are called elements.

Know the Terms  Battery : Combination of two or more cells is called a battery.  Fuse : A safety device that cuts off the electric current in a circuit if a sudden heavy current starts flowing in it.  Solenoid : A cylindrical coil of wire. Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 23 Flowchart

Electric Current Flow of electrons (electric charges) throughaconductor (wire) Flows through

Electric Circuit Effects of Electric Current

Heating Effect Magnetic Effect Components of Electric Circuit

Electromagnet Applications Fuse

Application

MCB

Electric Bell

Gong

Hammer

Electromagnet Switch

– +

 24 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Chapter - 15 : Light Let’s Revise  Light is a form of electromagnetic radiation (radiation energy) which produces in us the sensation of vision.  Light travels along straight line.  A highly polished or shiny surface, such as mirror reflects most of the light falling on it.  Reflection of light : A mirror or shiny surface that acts as mirror, changes the direction of light that falls on it. This change in the direction of light by a mirror is called reflection of light.  Spherical mirrors : The surface of a mirror or a shining spoon could be curved. The most commonly used type of curved mirror is the spherical mirror. The reflecting surface of such mirrors can be considered to form a part of the surface of a sphere. Such mirrors, whose reflecting surfaces are spherical are called spherical mirrors.  The surface of water (clear fresh water) can also act like a mirror and change the path of light.  Image (optical) : An optical appearance produced by the light or other radiations from an object reflected in the mirror or refracted through a lens is called image.  Convex mirror always forms virtual images which are erect and smaller in size than the object. However, convex mirrors form images of objects spread over a large area.  Doctors use concave mirrors for examining eyes, ears, nose, throat and teeth. These are also used as reflectors of torches, head lights of cars etc. Convex mirrors are used as side mirrors in cars etc.  Lenses are also used to form images. Convex lenses are thicker in the middle than at the edges. On the other hand, concave lenses are thinner in the middle than at the edges.

 A concave lens always forms erect, virtual and diminished image. It is called diverging lens because it diverges the light falling on it.  Convex lenses can form both real and virtual images depending upon the position of object. These give magnified images when objects are very near the lens. A convex lens is called converging lens as it converges the light falling on it.  White light splits into seven colours when it enters a prism, viz, violet, indigo, blue, green, yellow, orange and red. This phenomenon is called dispersion of light.

Know the Terms

 Concave mirror : If the reflecting surface is on the inside, the mirror is called concave mirror.

 Convex mirror : If the reflecting surface is on the outside, the mirror is called a convex mirror.

 Focal length : The distance between the optical centre and the focus of a lens is called the focal length of the lens.

 Lens : A transparent medium bounded by two surfaces of which at least one is spherical is called a lens.

 Real image : It can be formed on a screen.

 Spectrum : The bands of colours seen when white light is separated into its different colours.

 Virtual image : An image which cannot be formed on a screen is called a virtual image. Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 25 Flowchart LIGHT It is the natural agent that stimulates sight and makes things visible.

Properties of Light

Rectilinear Propagation Reflection of Light Dispersion of Light

Reflecting Surfaces Images Types

Plane Curved Lenses Real Virtual Mirror Mirror

Lateral Inversion

Types Types

Concave Mirror Convex Mirror Convex Lens Concave Lens If thereflecting surfaceis If thereflecting surface inside, mirrorisconcave. is outside, mirroris convex. Image formedisvirtual, upright and diminished.

 Chapter - 16 : Water : A Precious Resource

Let’s Revise  Water is the most essential natural material for human beings, plants and animals.  Water exists as snow or frost in solid state, as normally available in liquid state and as steam or water vapour in gaseous state.  The various sources of water are : oceans (seas), rainwater, groundwater, rivers and lakes. This comprises nearly three-fourth part of the earth’s surface.  Water is maintained on earth by various processes which make the water cycle, still there is shortage of water at many places due to many human activities.  The upper limit of underground water is called water table.  The process of seepage of water into the ground is called infiltration.  Water cycle : Ocean is the biggest storehouse of water which on evaporation forms clouds and which after condensation falls down as rain. After rain, it is passed through rivers and gets collected again in the ocean. The circulation of water in this manner is known as water cycle. The cycle is also performed through living beings like absorption and transpiration of water by plants and drinking by animals. Animals lose water during respiration and perspiration. They also lose water through excretion. 26 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII

Fig. Water Cycle  Groundwater : The water of rain or from other sources like ponds, which seeps or percolates under the ground and collects over the impermeable rocks is called groundwater.  At places, the groundwater is stored between layers of hard rocks below the water table. This is known as aquifer.  Scanty rainfall, increasing population, increasing industries, agricultural activities and deforestation are some of the causes for the depletion of water table at some places.  Wastage of water should be avoided. Besides recharge of water to the ground should be strengthened. Rainwater harvesting technique should be used to recharge, the groundwater.  Drip irrigation process of watering the plants should be started in the farms.  In order that water is available to future generations, we should use it economically.

Know the Terms  Aquifer : At places the groundwater is stored between layers of hard rock below the water table. This is known as an aquifer.  Infiltration : The process of seeping of water into the ground is called infiltration.  Water table : Level of ground water. Flowchart Water

Forms of Water Sources of Water Water Scarcity There are3forms of water : Surface of Water Groundwater • Seas and oceans • Rivers • Springs • Lakes and ponds

Precipitation n Clouds Condensatio Depletion of Water Table Water Vapour Rain, Hail, Snow

n Transpiratio

n Evaporatio Evaporatio Sea Soil Plants Water Water

Uneven distribution of rainfall Scanty rainfall Deforestation

Effect of Water Scarcity

On Plants On Life Water Management

Start wilting and ultimately • Crop failure dry up. • Spread of diseases Cannot prepare food and • Loss of life ultimately die. Water

Forms of Water Sources of Water Water Scarcity There are3forms of water : Surface of Water Groundwater • Seas and oceans • Rivers • Springs • Lakes and ponds

Precipitation n Clouds Condensatio Depletion of Water Table Water Vapour Rain, Hail, Snow

n Transpiratio

n Evaporatio Evaporatio Sea Soil Plants Water Water

Uneven distribution of rainfall Scanty rainfall Deforestation Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 27 Effect of Water Scarcity

On Plants On Life Water Management

Start wilting and ultimately • Crop failure dry up. • Spread of diseases Cannot prepare food and • Loss of life ultimately die.

 Chapter - 17 : Forests : Our Lifeline

Let’s Revise

 We obtain a variety of products from the forests that surround us.  Forest is a system and surrounding that consists of different plants, animals and micro-organisms.  In a forest, trees form the uppermost layer, followed by shrubs. The herbs form the lowest layer of vegetation.  Various layers of vegetation supply food and shelter to animals.  Various components of the forest are interlinked with one another.  Forests keep on growing and changing ; they can also regenerate.  In a forest, an interaction always occurs among air, water, soil and living organisms.  Forests save the soil from erosion.  Soil enables forests to grow and regenerate.  Forests are a great boon to the forest dwelling communities.  Forests produce a great deal of effect on climate, water cycle and air quality.  Owing to favourable climatic conditions, huge populations of plants and animals are found in tropical rain forests.  Animals in tropical rain forests are adapted in such a way that they eat a variety of foods in order to overcome the struggle for food and shelter.  Some adaptations of animals living in tropical rain forests include living on trees, developing long and large beaks, strong tails, bright colours, loud voice, sharp patterns, sensitive hearing, sharp eyes, diet of fruits thick skin and ability of camouflage in order to protect themselves from predators.

Know the Terms  Canopy : Branches of the tall trees which look like a roof are known as canopy.  Decomposers : Micro-organisms which convert dead plants and animals to humus are called decomposers.  Deforestation : Cutting of the plants.  Humus : Decaying biological matter of the soil is known as humus.  Soil erosion : Depletion of upper layer of soil. 28 ] Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII Flowchart

FORESTS Large areas of land thickly covered with trees, bushes etc.

Importance of forests Interdependence of Plants Deforeslation Conservaton of Forests and Animals in Forests • Provide timber. • Purify air. • Plants and animals depend •Do not allow overgrazing. • Provide shelter. on each other to remain alive. • Promote afforestation. • Prevent soil erosion. • All organisms interact with • Protect wildlife. • control floods. each other and their physical • Control forest fires. • Noise absorbers. environment to derive energy and survive.

Food Chain Food web

A system of interdependent food chains used to represent various relationships of organisms.

Grass Rabbit (Producer) (Primary consumer) Fox Lion (Secondary (Tertiary consumer) consumer)

 CHAPTER - 18 : Waste-Water Story Let’s Revise  Used water is waste water which can be recycled.  Waste water is produced in houses, industries, agricultural fields and in other human activities. This is known as sewage.  Sewage is a liquid waste which causes water pollution as well as soil pollution.  Waste water is treated in a sewage treatment plant.  When underground sewage systems and refuse disposal system are not possible, the low cost on-site sanitation system may be adopted.  Byproducts of waste water treatment are sludge and biogas.  Open drain system is a breeding ground for flies, mosquitoes and organisms which spread diseases. Know the Terms  Waste water : It is the used dirty water which may be black-brown, rich in lather, mixed with a discharge from sinks, showers, toilets, laundries etc.  Clean water : Water that is fit for use and safe for drinking is known as clean water.  Cleaning of water : It is a process of removing pollutants from water before it is released into a water body or is reused.  Sewage treatment : It refers to the process of treating the dirty water from households and industries. The treated water is released into water bodies, such as streams and rivers. This water can be used again for supplying drinking water, irrigation of crops and for aquaculture.  Sewage is waste water discharged from industries, hospitals, offices, homes and rainwater that is washed off roads and rooftops. Sewage is a liquid waste that may contain organic impurities (such as urine, faeces), inorganic impurities, nutrients (e.g., phosphates), disease causing bacteria and other microbes.  Sewers : A network of big and small pipes that carries waste water (sewage) is called sewers, forming the sewerage. Sewers carry sewage from the point of being produced to the point of diposal-treatment plant.  Contaminants : The dissolved and suspended impurities present in water are called contaminants.  WWTP : It stands for Waste Water Treatment Plant. Here, by physical, chemical and biological processes, contaminants of waste water are removed.  Sludge : Waste water solids like faeces, which settle down at the bottom of a large tank and are removed with a scraper are called sludge. Oswaal CBSE Chapterwise Quick Review, SCIENCE, Class-VII [ 29  Clarified water : Water which is cleared from the floatable substances like oil and grease by a skimmer is called clarified water.  Anaerobic Bacteria : Bacteria which can grow and multiply in absence of free oxygen are called anaerobic bacteria.  Biogas : The gas that is produced by decomposition of sludge by the anaerobic bacteria is known as biogas. Flowchart WASTEWATER

Rich in lather, mixed with oil, black-brown water that goes down the drains from sinks, showers, toilets, laundries is called wastewater.

Sewage

Sewage disposal Sewage Treatment

Better Housekeeping Practices

Wastewater Treatment Plant (WWTP) Wastewater passes through screens to remove large objects.

It goes toagrit and sand removal tank at low speed.

Water is allowed to settle in large tank.

Floating solids removed with skimmer Settled solids (sludge) removed with scraper.

Cleared water is called clarified water.

Water is then decomposed by anaerobic bacteria inatank and air is passed.

Microbes settle at bottom as activated sludge and water from top is removed.

