Notes

Diseases * Health is a state of physical, mental and social well being. * Disease is an unhealthy condition caused by microorganisms, improper diet or is inherited. * Bacteria cause diseases like typhoid, cholera, tuberculosis and anthrax. * Viruses cause the common cold, influenza, dengue fever, AIDS and rabies. * Fungi cause skin infections. * ... Read more

Production and Propagation of Sound * Sound is a form of energy that produces the sensation of hearing in our ears. * Sound is produced due to the vibration of objects. * Intensity of sound is the amount of sound energy incident per unit time per unit area. * Sound propagates through a medium. * ... Read more

Work * Work done by force acting on an object is equal to the magnitude of the force multiplied by the displacement of the direction of the force. Conditions for work to be done: *  A net force should act on an object. *  The object must be displaced in the direction of the net ... Read more

Kepler’s Law of Gravitation * To resolve shortcomings of the models propounded by Ptolemy and Copernicus, * Kepler propounded three laws on planetary motion. * Kepler’s first law, the law of orbits, states that the orbit of a planet is an ellipse with the sun at one of the foci. * An ellipse is a ... Read more

Force * Force is an agent that tries, successfully or unsuccessfully, to move a body at restor to stop a moving body. * A force can change the state of a body at rest, the state of motion of a body under motion, the direction of motion of a moving body or the shape of ... Read more

Introduction to Motion * Motion is a state of an object when there is a change in the position of the object with respect to its surroundings. * An object moving along a straight line or in a specified direction is said to have one-dimensional motion or linear motion. * If an object moves in ... Read more

Classification of Living Organisms * A process of gradual and progressive change or development in characteristics is known as evolution. * Organisms are grouped at various levels: Kingdom, Phylum for animals or * Division for plants, Class, Order, Family, Genus and Species. * Kingdom Monera consists of prokaryotic cell consisting of bacteria, small onecelled organisms. ... Read more

Plant Tissues * Tissues are a group of cells similar in structure and functions. * Plant tissues include meristematic and permanent tissues. * Permanent tissues often form protective covering in the form of epidermis and cork. * Permanent tissues are of two types: simple and complex. * Simple tissues include parenchyma, collenchymas and sclerenchyma. * ... Read more