Chapter 16: Management of Natural Resources 1. Introduction Anything in the environment which can be used is called a natural resource. Management of natural resources refers to controlling the use of resources to avoid wastage and maximize effectiveness. Ganga Action Plan (GAP) was initiated to reduce the pollution load of river Ganga by more than … Read more
Chapter 15: Our Environment Introduction The environment includes our physical surroundings like air (or atmosphere), water bodies, soil (land) and all organisms such as plants, animals, human beings, and micro-organisms like bacteria and fungi (called decomposers). Waste materials produced by human and animal activities are poisonous to some extent and can be divided into: Biodegradable … Read more
14. SOURCES OF ENERGY Characteristics of a good fuel: High calorific value Less smoke Less residue after burning Easy availability Inexpensive Easy to store and transport Fossil fuels: Were formed millions of years ago, when plants and animal remains got buried under the earth and were subjected to high temperature and pressure conditions. E.g.: Coal, … Read more
Chapter 13: Magnetic Effects of Electric Current Magnet Attracts iron, cobalt & nickel. Freely suspended magnet aligns in North-South direction. Uses of Magnets Radio & stereo speakers Refrigerator doors Audio & video cassette players Computer hard disks & floppies Children’s toys Magnetic Field & Field Lines The region around a magnet where magnetic force is … Read more
Electricity 1. Positive and Negative Charges Definition: The charge acquired by a glass rod when rubbed with silk is called positive charge, while the charge acquired by an ebonite rod when rubbed with wool is called negative charge. 2. Coulomb (C) SI Unit of Charge: One coulomb is defined as the amount of charge that … Read more
The Human Eye and the Colourful World 1. The Human Eye The human eye is a natural optical instrument used for vision. It functions similarly to a camera with a lens and screen system. Retina: Light-sensitive screen inside the eye where the image is formed, containing rods and cones. Cornea: Thin membrane covering the eyeball, … Read more
Light: Reflection and Refraction 1. Ray of Light A line drawn in the direction of propagation of light is called a ray of light. 2. Beam of Light A group of rays of light emitted by a source of light is called a beam of light. A light beam is of three types: Parallel beam: … Read more
Heredity and Evolution 1. Heredity The transmission of characters from parent to their offspring is known as heredity. The study of heredity and variations is known as genetics. Clones are organisms that are carbon copies of one another. Variation in sexually reproducing organisms is caused due to factors like environment, crossing over, recombination of genes, … Read more
Diversity in Living Organisms 1. Reproduction The production of new organisms from existing organisms of the same species is known as reproduction. 2. Asexual Reproduction Modes of asexual reproduction used are: Binary fission Multiple fission Budding Spore formation Regeneration Vegetative propagation Tissue culture Fragmentation 3. Sexual Reproduction In sexual reproduction, a male gamete (germ cell) … Read more
Control and Coordination Animals- Nervous System: Nervous system is the organ system present in the animals to control and coordinate different activities of the body. Nervous system comprises of the brain, the spinal cord, and a huge network of nerves that are spread throughout the body. The nervous system is responsible for sending, receiving and … Read more