5th Class

           Photosynthesis   Photosynthesis is derived from two words, photo + synthesis. 'Photo' means light and 'synthesis' means manufacturing, i.e. manufacturing food in the presence of light.   All green plants prepare its own food with the help of carbon dioxide and water in the presence of chlorophyll and sunlight. In this process solar energy is converted into chemical energy. The function of chlorophyll is to absorb solar energy.   Absorption of carbon dioxide and evolution of oxygen takes place through the leaves.   Water is obtained from the soil through the roots and transported to leaves for photosynthesis. Food prepared in the leaves transported to all the parts of the plants. Both the process are carried out with the help of veins. more...

   Introduction   Wide variety of living things, from very simple algae to very complex flowering plants, exist in the plant kingdom. Plants convert useful solar energy into chemical energy of food in the process of photosynthesis. Plants are seen everywhere, even in the desert, in the aquatic medium, in the hot damp places and in very cold places. Botany is the science which deals with the study about the plants.                                                Plant's Classification   Paddy, wheat and maize are monocot plants belong to the grass family.     Pea, bean, gram are dicot plants belong to the leguminous family.   more...

       Volcano   A volcano is an opening in the earth's surface which allows hot, molten rock, ash and gases to escape from below the surface. These burst out of the crust at the top or holes around the sides of the volcano through weak points. Some volcanoes are formed under the sea. When the lava cools down, the area formed looks like a new island. The barren island is the only active volcano in the Indian subcontinent. It is located in the Andaman and Nicobar is lands.       Tidal Waves Tidal waves are called tsunami. Tsunami are caused by an undersea earthquake or by a severe hurricane or cyclone. Storm waves from the sea come rolling towards the shore then cause destruction on the seashore in seconds. If these is already high tide then more...

     Natural Calamities   Natural calamities are some disasters caused by nature which might affect our lives. Some of the natural disasters are earth quakes, volcanoes tidal waves and thought.          Earthquake An earthquake is a sudden shaking of the ground caused by the movements or vibrations deep inside the earth. The earth's upper layer, the crust, is made of large and small plates. The layers of the earth under the plates are hot and in a molten state because the core below is externally hot these layers under the plates are constantly moving. Such movements cause the plates to slide smoothly against each other. There movements can sometimes give rise to earthquakes. When the ground shakes, houses, buildings and bridges shake. When it lasts for some time, roads crack, structures shatter and communication systems collapse. more...

       Introduction   Everything around us is the component of our environment. The components of our environment affect on our health and day to day life. We get disease in the polluted environment and a good environment makes us healthy. The polluting elements in our environment are called pollutants. In this chapter, we will study about the pollutants in our environment and method by which we can eliminate these pollutants.             Pollution Human activities lead to the production of waste materials that had deteriorated our environment and make them unsuitable for the life. Unwanted and undesirable substances present in air, water and soil are called as pollutant. For example. Sulphur dioxide, Nitrogen oxides, Lead oxides. Hydrocarbons, Fly ashes, Smoke, Dust particles etc. On the basis of the contaminated source, pollution can be broadly classified more...

       Air Pollution   Overpopulation, industrialization, modern life style and advancement in science technology has lead to the thoughtless use of natural resources, which in turn spoil air for other activities. This is called air pollution. Look at the following picture of the causes of air pollution   Look at the following picture of the causes of air pollution Deforestation is one of the big causes of air pollution. Trees are the natural air purifier. Deforestation increase the concentration of carbon dioxide in the air and thereby pollutes it. Eruption of ash from the volcano causes air pollution. Concentration of carbondioxide, hydrogen chloride and sulfur dioxide increases due to the eruption more...

       Water Pollution   Water is an essential component of all forms of life. It is odorless, colorless and transparent liquid. It has the capacity to dissolve maximum substances in it and hence is used as a universal solvent. But now a days due to human activities, over population, industrialization and unawareness, the smell, odur and unique quality of water is being contaminated, which is called water pollution.            Consequences of Water pollution                                                Eutrophic lake - a threat to aquatic life               Water contamination leads to untimely death of aquatic lives         Polluted water causes disease more...

   Soil Pollution   Excessive, unorganized agriculture and no judicious use of chemical fertilizers, pesticides, weedicides, herbicides and insecticides etc contaminate the soil which is called soil pollution. Polluted soil leads to the growth of polluted plants and this toxicity finally enters the human/ animal's body through food chain.              Causes of Soil Pollution                  Consequences of Soil Pollution                Polluted Soil Causes Disease                   How can we maintain the quality of soil? Look at the following chart to understand the more...

      Noise Pollution   It is the loud unwanted and undesirable sound. Sound at 80 decibel or more gives unpleasant experience and regarded as noise pollution. 90% of noise pollution is due to the noise produced by the motor vehicles etc.   Look at the following picture of the causes of noise pollution:                    Classification of Sound in Decibel (db) Sounds                                         Decibel (db) Normal talking                                      40 db Whisper                   more...

       Introduction   There are eight planets, which revolve around the Sun. Sun is at the centre of the solar system. Some planets in our solar system are called inner and some are outer planets. Inner and outer planets are categorized according to the distance from the Sun. In this chapter, we will study about the solar system and its components.               Our Universe Universe is everything that exists in totality. For example stars, planets. Sun, steroids, all other celestial bodies etc. All stars and clouds are made up of hydrogen and helium.                Astronomy The branch of science that deals with the study of space Is called astronomy.               Planets Planet more...