Articles

NCERT Chapter Summary: Tissues

Tissue is a group of cells similar in structure and function. Plant tissues are of two main types - meristematic and permanent.

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Light Energy

Light is the form of energy which makes the objects visible to us. When light reaches from object to our eyes, it becomes visible to us. Reflection, refraction and dispersion are the important properties of light.

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Physiography of India

India is a large country. India is the seventh largest country of the world. It extends from the state of Jammu and Kashmir in the North to the state of Tamil Nadu in the South; from the state of Arunachal Pradesh in the east to the state of Gujarat in the west.

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Human Impact on Environment

Environmental problems may arise due to natural disasters or due to human activities.

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Natural Environment

In an ecosystem, living organisms interact among themselves and also with the surroundings continuously and yet maintain a balance. Ecosystem is divided into two basic categories namely terrestrial and aquatic.

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Carbon and its Compounds

Diamond has a three-dimensional network of covalently bonded carbon atom. It is hard and colourless. It has high melting and boiling point and is a good conductor of heat but poor conductor of electricity.

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Metals and Non-metals

Elements are broadly classified as metals nonmetals. Metals can be distinguished from non-metal on the basis of their physical properties like malleability ductility, lusture.

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Water

Water is the abundant natural resource available. Although sea water is the largest natural source of water, it is unfit for domestic use and drinking. Water is essential for survival of all living beings.

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Air

Air is a mixture of different gases. It contains oxygen, Nitrogen, Argon, Carbon dioxide and traces of some inert gases. It also contains water vapour.

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Heredity

Features passed down from one generation to the other is Heredity or Inheritance. Genes control heredity. Differences in features of individuals of the same species is variation.

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Control and Coordination

Nervous system (NS) and endocrine system together ensure that all the parts of the body work in a controlled and coordinated manner.

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Excretion

Excretion is the removal of harmful wastes like urea by kidneys, sweat from skin and CO2 by Lungs.

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Transportation (Blood Circulation)

Blood transports food and oxygen to all the cells of the body. It is made of fluid plasma and cells. Plasma which transports glucose, enzymes and hormones to cells, carries waste material from liver to kidneys for removal.

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Respiration

Blood vessels carry oxygen from alveoli to tissues. Cells of tissues take up the oxygen. In the mitochondria of the cells, oxygen acts upon glucose to yield energy and release carbon dioxide. This is called cellular respiration.

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Nutrition

Life Processes such as Nutrition, Respiration, Circulation and Excretion are necessary for the survival of living beings. Energy is needed for running life processes.

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Cells and Tissues

Cell is the structural and functional unit of life. A typical cell includes a cell membrane, cytoplasm and genetic material either within the nucleus or in the cytoplasm.

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History of Life on Earth

Earth is the only planet in our solar system which sustains life. But earth was not the same as it is today. It was a ball of gases when it was first formed about 4.5 billion years ago. Earth cooled and chemicals of life were synthesized in water - chemical evolution.

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Classification of Living Organisms

The earth came into existence 4-5 billion years ago and life originated around 3.4 billion years ago. In these many years, approximately 15 million different kinds of organisms have evolved. The wide variety of organisms is termed biodiversity.

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Sound and Communication

Sound is the form of energy which gives the sensation of hearing. It travels in the form of waves.

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Magnetic Effect of Electric Current

Magnet is a naturally occurring or artificially designed material which has a peculiar property of attracting some materials like iron, nickel and cobalt, called magnetic materials.

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Electrical Energy

There are two types of charges: positive charge, i.e., the charge that a glass rod acquires when rubbed with silk and negative charge, i.e., the charge which an ebonite rod acquires when rubbed with flannel.

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Thermal Energy

Thermal energy, also called heat, is a form of energy which gives us sensation of hotness. Like other forms of energy its SI unit is Joule (J). Temperature is a measure of hotness of a body. It is measured in, ºF, ºC or K, with the help of a device called thermometer.

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Work and Energy

Work: The product of displacement and force in the direction of displacement of a body is called work.

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Gravitation

The gravitational force due to earth is called gravity.

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Force

Inertia: The property of a body which tends to keep the body in its state of rest or of uniform motion is called inertia.

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Motion

A continuous change in the position of the object with respect to time is called motion.

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Acids, Bases and Salts

Acids are the substances which taste sour, change blue litmus red, are corrosive to metals and furnish H+ ions in their aqueous solutions. Bases are the substances which taste bitter, change red litmus blue, feel slippery and furnish OH- ions in their aqueous solutions.

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Chemical Bonding

The basic cause of chemical bonding is to attain noble gas configuration either by transfer of electron from a metal to non- metal or by sharing of electrons between two non-metal atoms.

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Periodic Classification of Elements

The first classification of elements was as metals and non-metals. After the discovery of atomic mass (old term, atomic weight) it was thought to be the fundamental property of elements and attempts were made to correlate it to their other properties.

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Atomic Structure

According to Dalton’s atomic theory, the atom is considered to be the smallest indivisible constituent of all matter. This theory could explain the law of conservation of mass, law of constant composition and law of multiple proportions.

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Medieval World

There was transformation of European Society after the downfall of the Roman Empire, and the birth of a new religion called Islam which led to the founding of a vast empire that originated in West Asia and spread out over a large part of the world.

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Modern World

With the decline of feudalism, the restrictions on peasants become a thing of the past simultaneously, the period witnessed the rise of powerful merchant class, which financed discoveries of new lands. These, with other factors, brought about the Industrial revolution which led a sea change throughout the world. This was the beginning of the Modern Age.

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Age of Revolutions

There was a very strong dissatisfaction with political leadership and people started demanding more participation in the affairs of the State.

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Imperialism and Colonialism

Industrial Revolution brought social and economic changes that transformed the agricultural society to a modern industrial society. The industrialised nations needed raw materials for their industries as well as markets for their finished good.

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World Wars

The murder of Archduke Francis Ferdinand became the immediate cause of the war.

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Religious and Social Awakening

In the first half of 19th century the society was backward due (i) lack of education and (i) subordination of women. This prevented society's progress. Many reformers came up during this period who contributed to religious and social awakening helped in transforming the society for betterment.

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Ancient World

Discovery of metal led to human civilisation becoming highly evolved. Copper was the first metal used by human beings; the cultures based on use of both copper and stone are called Chalcolithic Cultures.

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Chemical Reactions and Equations

A chemical equation is a shorthand description of a reaction. It symbolically represents the reactants, products and their physical states.

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Atoms and Molecules

According to law of constant proportions, a sample of a pure substance always consists of the same elements combined in the same proportion by mass.

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Matter

Anything that has mass and occupies space is matter. There are three different physical states of matter in which a substance can exist - solid, liquid and gas.

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Measurement

Measurement is a process of comparing a physical quantity with a standard quantity. The standard quantity used to compare a physical quantity for its measurement is called unit.

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