General Science is integral part of every competitive exams. Whether it is UPSC or SSC or state PCS general science is everywhere. And one of the effective methods of the preparation of GS is reading NCERT books. In this article i have summarized class 7th NCERT science book. This article is part 2 of the ongoing ncert science summary series. If you have not read part-1 of this series yet then click here to read it. Read this article till the end to benefit the maximum.
Chapter 1 – Nutrition in Plants.
- Autotroph : Organism which make their own food are called autotrophs. e.g. plants
- Heterotroph : Those organism who can’t make their own food and rely upon plants and animals. e.g. insects.
- CO2 from air is taken in through the tiny pores present on the surface of leaves. Such pores are called Stomata. These pores are surrounded by Guard cells.
- Leaves have green pigment called Chlorophyll. It captures the energy of sun-light.
- Sun-light is used to synthesis food from co2 and water.Since synthesis of food occurs in presence of sun-light, it is called Photo- Synthesis.
- Food is stored as “Starch” in plants.
- Algae also contains chlorophyll hence, they can prepare their food by own.
- Cuscuta(Amarbel) is heterotrophic plant, that’s why they are called parasite.
- Insect eating plants are called Insectivorous. e.g pitcher plant.
- Saprotrophs : It is mode on nutrition in which organism take nutrients from dead and decaying matter.
- Symbiotic relationship : Some organisms live together and share shelter and nutrient. e.g. plant & fungi.
- Rhizobium : The bacterium called rhizobium can take atmospheric nitrogen and convert it into soluble form. Rhizobium lives in roots of gram, peas, and moong.
- During photosynthesis, carbohydrate is made in plant, which is stored as Starch.
Chapter 2 – Nutrition in Animals
- Breakdown of complex components of food into simpler substance is called Digestion.
- The process of taking food into the body is called Ingestion.
- The saliva breakdown the starch into sugar.
- In stomach digestive juices breakdown the protein into simpler substance.
- Small intestine is highly coiled and it is about 7.5 M long.
- Liver is reddish brown gland situated in the upper part of the abdomen on right side.
- Liver is the largest gland of the body.
- Liver secrets bile juice that is stored in the sac called “Gall bladder”.
- Bile plays important role in digestion of fat.
- Pancreas secrets “pancreatic juice” which act on carbohydrate, proteins, and fats and change them into simpler form.
- Digested food is pass into the blood vessels , this process is called Absorption.
- Inner wall of small intestine have thousands of finger like outgrowths. they are called “villi“.
- Villi increase the surface are for absorption of digested food.
- The using up of digested food is called “Assimilation“.
- In cells, glucose breakdown with the help of O2 into CO2 & water and energy is released.
- Large intestine is wider and shorter than small intestine. It is about 1.5 M . Its function is to absorb water and some salts.
- The faecal matter is removed from the anus. TYhis is called “Egestion”.
- Chewing food again and again is called “Rumination”. e.g. buffalo.
- Cellulose is a type of carbohydrate which can’t be digested by human and many other animal. But ruminant can digest cellulose, because they have certain bacteria.
- Amoeba is single cell organism found in pond water. It captures food through “Pseudopodia” or false feet.
- Starfish capture food by removing stomach out of the body.
Chapter 3 – Fibre to Fabric.
- Wool industry- Sorters get infected by bacterium “Anthrax” , which causes fatal blood disease called “Sorter’s disease”.
- The rearing of silkworm for obtaining silk is called “Sericulture”
- The most common silk moth is “mulberry silk”.
- Silk comes from silkworms and wool is obtained from sheep, goat and yak. Hence silk and wool are animal fibres.
- Silkworm are caterpillars of silk moth.
- Cocoon yields silk fibre.
Chapter 4 – Heat.
- Thermometer is a device used for measuring temperature.
- Clinical thermometer is used to measure body temperature ( 35 deg. cel to 42 deg. cel. ). For other purpose, we use laboratory thermometer. It ranges from (-10 degree Celsius to 110 degree Celsius).
- Temperature of human body is 37 degree Celsius.
- Heat transfer takes place from higher temperature to lower temperature.
- In solid, heat transfer by Conduction.
- In liquid and gas heat is transferred by Convection.
- No medium is required for transfer of heat by Radiation.
- Woolen clothes keeps us warm during winter. It is so because wool is a poor conductor of heat and it has air trapped between the fibres.
Chapter 5 – Acids, Bases and Salts.
- Acids are sour in taste.
- Bases are bitter in taste and soapy in touch.
- Acid turns blue litmus red. Bases turns red litmus blue.
- An acid and base neutralize each other and form salt.
- Litmus is extracted from “Lichens“.
- Acid rain contains CO2, NO2
|Name of acid||Found in|
|Formic acid||Ant’s sting|
|Citric acid||Citrus fruits, lemons|
|Ascorbic acid (Vitamin C)||Amla, citrus fruits|
|Name of Base||Found in|
|Calcium Hydroxide||Lime water|
|Ammonium hydroxide||window cleaner|
|potassium and sodium hydroxide||Soap|
|Magnesium hydroxide||Milk of magnesia|
Chapter 6 – Physical and Chemical Changes.
- Size, color and state are physical properties.
- The change in which a substance undergoes a change in its physical properties are called physical change.
- Physical change is generally reversible. No, new substance is formed.
- A change in which on or more new substance is formed called chemical change.
- The process of depositing layer of Zinc on iron is called Galvanization.
- When CO2 is passed through lime water it turns milky due to formation of calcium carbonate (CACO3).
- Chemical name of baking soda is sodium bicarbonate (NahCO3)
Chapter 7 – Weather, Climate and Adaptations of Animals to Climate.
- The day to day condition of the atmosphere at a place with respect to temperature, humidity, rainfall, wind-speed etc is called weather at that place.
- The average weather pattern taken over a long time say 25 years. is called Climate of that place.
- Maximum temperature of day occurs n the after noon, while the minimum temperature occurs in morning.
- Polar regions are cold, throughout the year.
- Tropical rain forest have good condition for life.
- Tropical region are usually hot and humid.
Chapter 8 – Winds, storms and cyclones
- Moving air is called Wind.
- Air moves from high pressure to low pressure.
- Warm air is lighter than the cold air.
- Cyclone is known as “Hurricane” in America and “typhoons” in Philippines and Japan.
- Uneven heating of Earth is main cause of wind movements.
- Tornadoes – A tornado is a dark funnel shaped cloud that reaches from the sky to the ground.
- The center of cyclone is a Calm area, it is called eye of the storm.
Chapter 9 – Soil
- The rotting dead matters in the soil is called humus.
- Soil is formed by breaking down of rocks by the action of wind, water & climate. This process is called weathering.
- A vertical section through different layers of the soil is called ” soil Profile”.
- The mixture of rock particles, and humus is called soil.
- If soil contains greater proportion of big particles, it is called sandy soil.
- If the proportion of fine particles is relatively higher, then it is called Clayey soil.
- If the amount of large and fine particle are same, then the soil, is called “Loamy” soil.
- Cotton is grown in sandy loam soil.
- Clay and loam are suitable for growing wheat, gram and paddy.
- Water is highest in sandy soil and least in clayey soil.
Chapter 10 – Respiration in Organisms
- The process of breakdown of food in the cell with the release of energy is called cellular respiration. It takes place in the cell of organisms.
- When the breakdown of glucose occurs with the use of oxygen, then it is called aerobic respiration.
- Breaking down of food particle, without oxygen is called Anaerobic respiration.
- Organism which can survive in the absence of air is called anaerobes. e.g. yeast.
- In the absence of oxygen , glucose break down into alcohol and CO2. Yeast are used for making alcohol. They are single cell organism.
- During heavy exercise , our cells temporary respire anaerobically which results in formation of Lactic acid causing muscles to cramp. this can be cured by taking hot bath. which improves the circulation of blood.
- Average breathing rate is 15-18 times/minute. During exercise breathing rate becomes 25 times per minute.
- When we inhale air there is 21% oxygen and 0.04% CO2.
- When we exhale air there is 16.4% oxygen and 4.4% CO2.
- Cockroach has small openings on the side of the body, they are called Spiracles( They breath through it).
- Insects have network of air-tube called “Trachea” for gas exchange.
- Earthworm respire through skin.
- Frogs have pair of lungs like human beings, they can also breath through their skin, which is moist and slippery.
- Gills in fish help them to use O2 dissolved in water.
Chapter 11 – Transportation in Animals and Plants
- Blood is connective tissue. This is only connective tissue which is found in liquid state.
- The fluid part of the body is called Plasma.
- RBC contains red pigment, which is called Haemoglobin.
- Haemoglobin bind O2 and transport it to different organ of the body.
- The presence of Haemoglobin makes blood red.
- The WBC fight against germs.
- Platelets help in clot formation.
- Arteries carry O2 rich blood from the heart to all parts of the body.
- The number of heart beats per minute is called pulse rate. Normal pulse rate is 72-80 per minute.
- Veins are the vessels which carries CO2 rich blood from all parts of the body to the heart.
- Pulmonary artery carries blood from heart to lungs.
- Pulmonary veins carries O2 rich blood from lungs to heart.
- Human heart has 4 chambers, two upper chamber is called Atrium and the two lower chambers is called Ventricles.
- Hydra doesn’t possess any circulatory system.
- A tissue is a group of cells which perform specialized function.
- Xylem transport water in plants.
- Phloem transport food in plants.
- Transpiration : this is process of loss of water through mini pore called Stomata.
- Birds,. Insects, lizards excrete Uric acid in semi-solid form.
- The main excretory product in human being is Urea.
Chapter 12 – Reproduction In Plants
- Flowers are reproductive part of plant.
- In asexual reproduction, plants can give rise to new plants without seeds.
- When new plants are produced from roots, stems, leaves , buds it is called Vegetative propagation.
- Budding – the small bud like projection coming out from the yeast cell is called a bud. The bud gradually grows and forms a new yeast cell.
- Fragmentation – An algae breaks up into two or more fragments. these fragments grow into new individuals.
- “Stamens” are the male reproductive part in plant and “Pistil” is the female reproductive part.
- The flowers which contain either the pistil or stamens are called unisexual flowers. e.g. corn, cucumber.
- The flowers which contain both stamens and pistil are called Bisexual pants. e.g. mustard, rose.
- Anther contains pollen grains which produces male gametes.
- Pistil consist of stigma. The female gametes or the egg is formed in the ovule.
- Male and female gametes fuse to form Zygote.
- The transfer of pollen from the anther to Stigma of a flower is called Pollination.
- If the pollen lands on the stigma of the same flower. It is called self-pollination.
- When the pollen lands on the stigma of another flower of the same plant or that of different plant of same kind, it is called cross-pollination.
- The cell which results after fusion of gametes is called Zygote.
- The process of fusion of male and female gametes is called fertilization. The Zeogete develops into embryo.
Chapter 15 – Light
- Light travels along straight line.
- Any polished surface acts as a mirror.
- An image which can be obtained on the screen is called real image.
- An image which can’t be obtained on the screen is called virtual image
- Image formed by plane mirror is Erect and virtual and of same size of object.
- Concave mirror form real and inverted image.
- Image formed by convex mirror is erect, virtual and smaller in size
- A concave lens always form erect, virtual and smaller image.
- Convex lens form real and inverted image.
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