Current Affairs 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. Roots absorb water from the soil   Path way of carbon dioxide and oxygen in and out of the plant body:   Oxygen is a byproduct in the photosynthesis process that leaves the plant body through the stomata, which is present in the leaves., also enters the body through the stomata. Mushrooms are grown in the dark places. It doesn't undergo photosynthesis process, rather it feeds on dead and decayed organic matter.   Mushroom obtains its food from dead decayed plant product   Some plants are parasitic in nature. They eat insects trapped by them. Such types of plants are called insectivorous plants, e.g. sundew, venus fly trap, pitcher plant etc. Insectivorous plants appear very attractive as they need to attract insects. They can even trap frogs, birds etc.                                                               Venus fly trap                                     Pitcher plant                                          Sundew              Respiration in Plants Like animals, plants also need energy; but to a little extent. Because plants don't have to move from one place to another in search of food like animals. This energy comes from the oxidation of the food prepared by leaves. Hence we can say that in the presence of oxygen food is broken down into CO2 and H2O along with the release of energy. Photosynthesis is a synthesis process and respiration is a breaking down process. Respiration is an opposite process of the process of photosynthesis.                    Adaptations in Various Plants Adaptations are favorable changes that enable an organism to increase its chances of survival.              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.     In this chapter we will study about gymnosperm and angiosperm (flowering plant).           Gymnosperm This group of plants bear naked seeds. Plants develop with erect stem and many branches. Male and female plants are separate. Leaves perform photosynthesis. For example, pinus, cycus, gnetum etc.                                                                           Pine tree                                                  Cycus tree                                               Naked Seeds in Cone            Angiosperm Angiosperm plants are highly developed. Seeds are not naked and closed inside an ovary. They have well differentiated leaves, roots and stems. Angiosperm are also called flowering plants, which are divided into two groups.   Ferns, mosses, fungi etc. do not have flowers, rather they possess spores, which grow into a new plant.                                         Mosses                                                Ferns

       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 the storm waves hit the land. They can cause severe damage.         Drought Drought are caused by poor rain fall. Land and water bodies dry up because of severe heat. This causes acute shortage of water for agriculture and domestic use. Because of scarcity of water animals and people suffer from food and drinking water.

     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. Also there is loss of life and property. Earthquakes is measured on a Richter scale People who study earthquakes are called seismologists. Earthquake can be detected with an instrument called a seismograph..

       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 into the following types:        Let us study in detail about the causes, consequences and preventive measures of these pollutions.

       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 from volcano . Indoor pollutants which are responsible for the air pollution, given in the picture above. We can minimize the pollution by using non polluting elements instead of the given elements.     Consequences of Air Pollution                               Taj mahal is corroded due to acid rain                               Hole in the ozone layer Taj mahal is corroded due to acid rain and hole in the ozone layer, which allows harmful ultra violet radiations to pass through it are the consequences of air pollution.          Air Pollution Causes Diseases Pollution can cause itching and irritation to eyes, skin, nose, throat and the respiratory tract. Pollution causes itching in eyes   Many respiratory problems Asthma, Bronchitis occur due to inhalation of poisonous gases.                       Respiratory problems   Pollution is injurious to plant or other animal also. Polluted air can damage lungs. It reduces visibility because of the presence of smoke, dust and vapors. Pollution can damage our nervous system and digestive system. Pollution can cause cancer and neurological disorder.             How to Minimize Air Pollution Look at the following chart to understand the method by which, we can minimize the air pollution: Use electric vehicle to reduce release of harmful gases in the air   CNG bus ? an eco-friendly bus Government has encouraged people to use LPG over coal and fire wood for cooking purposes as it improves air quality and 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 Water borne diseases can spread through contaminated water. Contaminated water contains pathogenic microorganisms.            How to minimize water pollution Look at the following chart to understand the method by which we can minimize water pollution:     Bathing animals in water sources should be stopped          Bury dead leaves          Which one of the following is a factor of water pollution? (a) Factory's wastes (b) Pesticides, insecticides, weedicides (c) Untreated sewage (d) All of these (e) None of these   Answer: (d) Explanation Factory's wastes. Pesticides, insecticides, weedicides and untreated sewage all are the factors of water pollution. Therefore, option (d) is correct and rest of the options is incorrect.           What may be the consequences of water pollution? (a) Killing of aquatic animals (b) Disturbance in the ecological balance (c) Disturbance in the food chain (d) All of these (e) None of these   Answer: (d) Explanation All are the possible consequences of water pollution that have been given in the option A, B, and C. Therefore, option (d) is correct and rest of the options is incorrect..

   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 method by which, we can maintain the quality of soil                    Cow dung adds organic matter to the soil to enrich soil fertility     Crop rotation – growing leguminous plants alternatively with cereals to maintain nutrients deficiency in the soil naturally                Find the statement which is true about soil pollution? (a) Brain and nerve can be damaged due to soil pollution (b) Malaria is caused by the protozoa that live in soil (c) Metals, pesticides, solvents, lead and oil spills are soil contaminants (d) Deforestation leads to soil pollution (e) All of these   Answer: (e) Explanation  Soil pollution causes many diseases. Hence, all the statements in the options are true. Therefore, option (e) is correct and rest of the options is incorrect.            Consider the following statements: Statement 1: Climate of a region is affected due to soil pollution. Statement 2: Climate of a region is not affected due to soil pollution. Which one of the following is correct about the above statements? (a) Statement 1 is true and 2 is false        (b) Statement 1 is false and 2 is true (c) Both statements are true                      (d) Both statements are false (e) None of these   Answer; (a)  Explanation Soil pollution affects vegetation which in turn affects climate. Therefore, option (a) is correct and rest of the options is incorrect..

      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                                                 20 db Aircraft                                                  120 db Atomic explosion                                 200 db Intensity of sound greater than 80 db causes noise pollution.                Consequences of Noise Pollution                  Noise Causes Disease           Our ears are sensible organs which work properly on a specific range of sound. The brain receives the incoming signal from the ears and analyze it. If the intensity of sound increases, it can damage the nervous system and ultimately may lead to hearing loss. The intensity of sound, which is greater than the sensible capacity of our ears is called loud and unpleasant sound. The effect of unpleasant sound on our head is just like inserting nails in the sensitive head.              How to Protect Ourselves from Unpleasant Sound Look at the following table to understand the method by which, we can protect ourselves from unpleasant sound::                       Arwin is playing violin and his sister Tina is listening music from the loudspeaker. Which one of the two children is creating more noise pollution as compare to other? (a) Arwin (b) Tina (c) Both Arwin and Tina (d) Neither Arwin nor Tina (e) None of these   Answer: (b) Explanation  Sound of violin is pleasant but sound of a loudspeaker is always noise because it is at high 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 is a celestial body made up of rocks, metals and gases, which revolve around a star, for example Earth, Mars, Jupiter etc. There are 8 planets in our solar system.               Star Star is a ball of hot and bright gases. There are billions of stars in the universe. Stars appear to twinkle from the surface of the earth.              Solar System Solar system means the family of the Sun that is the family of 8 planets orbiting around the Sun. It also includes the moons of the planets, asteroids, meteors and comets etc. Outer planets: The inner and outer planets are differentiated according to their distance from the Sun. There are four outer planets in our solar system, these are, Jupiter, Saturn, Uranus and Neptune. Inner planets: There are four inner planets, which are closest to the sun and revolve around the sun. These are Mercury, Venus, Earth and Mars.   Sun Sun is a medium sized, middle aged star and a ball of bright and hot gases. It has been burning and shining since billions of years and would continue to do so for about 10000000000 years. The temperature of the Sun's surface is about 6'000oc and the hotness increases from the surface to the core of the Sun. The Sun has spots, which are little bit cooler than the rest part. The Sun is in the second stage of its career. It is the nearest star to the Earth, about 15 crore kilometer from us. The diameter of Sun is 110 time the earth's diameter. The Sun's light looks white but actually it's a mixture o seven colors. Violet Indigo Blue Green Yellow Orange Red           Solar Eclipse This phenomena occurs when moon (Which circles around the earth) passes directly between the earth and the more...