Current Affairs 8th Class

        Protected Areas   Protected areas are areas of land or sea especially dedicated to the protection and maintenance of biodiversity. These are managed through legal means and have been set up within the legal frame work of Indian wildlife (Protection) Act,1972. Examples of protected areas are national parks and wildlife sanctuaries.                 National Parks A national park is a large area dedicated to conserve the environmental, natural resources and the wildlife therein. In a national park,

• Private rights are non-existent.
• Forestry operations, grazing of animals and hunting of animals are prohibited.
• Visitors are allowed to enter only for study, cultural and recreative purposes.
• Exploitation of habitat or wildlife is banned.

               Wildlife Sanctuaries A wildlife sanctuary is similar to a national park. However, it aims only at conservation of species. The wildlife sanctuaries have the following features:

• The boundary of a sanctuary is not limited by state legislation.
• The killing, hunting or capturing of any species is prohibited.
• Private ownership may be allowed to continue in a sanctuary.
• Forestry and other usages may be permitted, but to the extent that they do not affect wildlife adversely.

              Forest Reserves These forests are primarily reserved for raising trees for the production of timber or wood for industrial use. They also provide other products such as pulp, cellulose and medicinal plants. These forests cover 54.4% of the total forests area of 76.5 million hectares of land.                Zoological Gardens Zoological gardens or parks and zoos are places where the wild animal are kept in a protected environment under human care for public display. All the animals in a zoo are provided with the conditions similarto their natural habitats as far as possible. The aim is to enable us to learn about their behaviour and food habits.                Botanical Gardens Botanical Gardens play an important role in the conservation of plants species. They have collections of living plants for reference. Plant species are grown for identification purposes and each plant is labelled to indicate its scientific name, common name and vernacular name. a famous botanical garden of India is the Indian Botanical Garden situated at HOWRAH (Kolkata).                Which one of the following is a renewal resource? (a) Petroleum (b) Coal (c) Mineral deposits (d) Solar energy (e) None of these   Answer: (d)            Which one of the following statements is true? Statement 1: Botanical garden play an important role in the conservation of plant species. Statement 2: more...

         Conservation of Plants & Animals   Conservation, sustainable use and protection of natural resources including plants, animals, mineral deposits, soils, clean water, clean air, and fossil fuels such as coal, petroleum, and natural gas. Natural resources are grouped into two categories, renewable and nonrenewable. A renewable resource is one that may be replaced over time by natural processes, such as fish populations or natural vegetation, or is inexhaustible, such as solar energy. Nonrenewable resources are those in limited supply that cannot be replaced or can be replaced only over extremely long periods of time. Nonrenewable resources include fossil fuels and mineral deposits, such as iron ore and gold ore. Conservation activities for nonrenewable resources focus on maintaining an adequate supply of these resources well into the future. Natural resources are conserved fortheir biological, economic, and recreational values, as well as their natural beauty and importance to local cultures. For example, tropical rain forests are protected for their important role in both global ecology and the economic livelihood of the local culture; a coral reef may be protected for its recreational value for scuba divers; and a scenic river may be protected for its natural beauty.            Biodiversity Conservation Biodiversity, or biological diversity, denotes the number and variety of different organisms and ecosystems in a certain area. Preserving biodiversity is essential for ecosystems to respond flexibly to damage or change. For example, a single - species corn crop may be quickly destroyed by a certain insect or disease, but if several different species of corn are planted in the field, some of them may resist the insect or disease and survive.   Humans benefit greatly from the many medicines, crops, and other products that biodiversity provides. As many as 40 percent of our modern pharmaceutical medicines are derived from plants or animals. For instance, a small plant from Madagascar, the rosy periwinkle, produces substances that are effective in fighting two deadly cancers, Hodgkin's disease and leukemia. Unfortunately, human activities have greatly reduced biodiversity around the world. The 20th century encompasses one of the greatest waves of extinction, or elimination of species, to occur on the planet. The greatest threat to biodiversity is loss of habitat as humans develop land for agriculture, grazing livestock, industry, and habitation. The most drastic damage has occurred in the tropical rain forests, which cover less than seven percent of the Earth's surface but contain well over half of the planet's biodiversity. Only 8 percent of the rain forests in Madagascar, home of the rosy periwinkle, remain intact.            Deforestation Deforestation means large-scale removal of forest prior to its replacement by other land uses. Forests are removed for a variety of reasons, including agriculture, timber harvesting, and mining, and to make way for roads, dams, and human settlements. At the end of more...

       Food Preservation   Certain food materials, for example milk, vegetables, meat, fish, fruits, etc get spoiled easily. Because they contain lots of water, which helps in the growth of microorganisms. We can prevent these foods from spoiling by using some techniques i.e. either by physical or by chemical treatment. The process, which is used for the preservation of food is called food preservation. Some of the common methods used for the food preservations are sun drying, heating, refrigeration, deep freezing, addition of common salt or sugar, addition of mustard oil and use of chemical etc. The preservative, such as, sodium metabisulphate or citric acid and pasteurization can also be used for such purpose. Preservation usually involves the prevention of growth of microorganisms, which can oxidize fats and cause rancidity. It also includes inhibiting ageing and discoloration, that can occur during food preparation. Some of the methods used for preservation require the food to be sealed in air tight container after recontamination with microbes.    Food Preservation                    Food materials can be preserved for the longer time periods. There are different methods of food preservations, some are traditional and some are scientifically proved. The chemical which is used to preserved food articles are: (a) Acetic acid (b) Ethanol      (c) Citric acid (d) Ketone (e) None of these   Answer: (c) Explanation Citric acid is one of the chemical, which is used to preserve the food articles.            Antacids are the slow decomposition of fats and other oily products by the microorganisms. Which microorganism causes decomposition of fats in the food? (a) Virus (b) Algae       (c) Bacteria (d) Fungus (e) None of these   Answer: (c) Explanation The microorganisms, which spoil the food by oxidizing the food is bacteria.      

• Wearing a headphone for just an hour or so can increases the bacteria in your ears by 700 times, as these headphone creates a warm, and moist environment in ear canal, which is ideal for breeding of bacteria.
• There are about more than 75 to 100 trillion bacteria in the human body, which is more than the number of cell in the body.
• There are certain bacteria, which cause food to rot and decay, but never cause diseases.
• The poisons released by bacteria are called toxins. The toxin release by staphylococcus aureus, clostridium botulinum and bacillus cereus is called exotoxins.
• The consumption of shellfish, such as, cockles, mussels, oysters and clams, is commonly associated with viral food-poisoning.

   

• Microorganisms are the very small life forms, which cannot be seen by the naked eyes.
• They are found in all types of climatic conditions.
more...

         Medicinal Uses of Microorganisms   It is used for the production of antibiotics, which can kill the microorganisms causing diseases. It is prepared by growing a specific type of microorganisms. Some of the common types of antibiotic are penicillin, streptomycin and tetracycline. The first antibiotic was extracted from fungus in 1929 by Alexander Fleming. Antibiotics are very effective in curing many diseases caused by bacteria and fungus. However, they are not effective in treating disease caused by virus.              Vaccine Vaccine is a special kind of medicine, which is used to provide immunity against a particular disease. It is given to the healthy person, so that they get protected from certain types of diseases. A vaccine contains the dead or weakened, but alive microorganism of a disease. When it is introduce into the body of a healthy person, the body of the person responds by producing some substance called antibodies, in blood. The antibodies kills any 'alive' disease causing microorganisms present in the vaccine. In this way the vaccine provides immunity from the disease. The various diseases, which can be prevented by vaccination of children at the proper age are polio, smallpox, cholera, typhoid, hepatitis, T.B., tetanus, measles, rabies, diphtheria and pertussis. The vaccine for smallpox was discovered by Edward Jenner in 1798.                Increasing Soil Fertility Some bacteria fixes nitrogen by converting atmospheric nitrogen into nitrate, there by increasing the nitrogen content of the soil. This in turn increases the fertility of the soil. Blue green.algae fix atmospheric nitrogen. Rhizobium bacteria, present in the root nodules of leguminous plant, helps in nitrogen fixation.                Vaccines are the special kind of medicine given to the healthy person to prevent certain types of diseases. In particular, it is given to the children during early age to protect against certain types of disease. Name the person who discovered the vaccine for the small pox? (a) Alexander Fleming (b) Louis Pasture (c) A.Thomas (d) Edward Jenner (e) None of these   Answer: (d) Explanation Different vaccine were developed by different scientists, the vaccine for small pox was developed by Edward Jenner. Therefore, option (d) is correct and rest of the options is incorrect.               Some of the antibiotics are prepared from the microorganism and they are used for making vaccination. The first ever antibiotics prepared by Alexander Fleming in 1929 is: (a) Streptomycin (b) Tetracycline (c) Penicillin (d) Soframycine (e) None of these   Answer: (c) Explanation The first ever antibiotic prepared was penicillin.                Harmful Microorganisms Microorganisms are also harmful and they cause disease in human and animals. Those microorganisms are called pathogens. They more...

       Useful Microorganisms   At first it was believed that microorganisms are all harmful and cause diseases. But later on it was found to be not true. There are many microorganisms, which are useful to us, serving many purposes of human beings. They are utilized in making curds, bread and cake. They are also used for producing alcohol, wine and acetic acid. They can also be used for the preparation of medicines called antibiotics. Some of the microorganisms help to fix atmospheric nitrogen to improve the nitrogen content of the soil. They can recycle the organic matters from the nature. Some of the common antibiotics, which are made from the fungi and bacteria are penicillin, streptomycin and tetracycline. The first antibiotic is penicillin.               Cleaning of Environment There are some microorganisms, which decompose the organic wastes and reduce the complex matter into the simpler form. These matters get added up into the soil and increas its nutrient content, helping in the growth of new plant. In addition, they also help in recycling of nutrients present in the nature, which can be used as food by the green plants.              Commercial Uses of Microorganisms Microorganisms are used for the large scale production of alcohol and acetic acid. Yeast is used for production of alcohol, in making of wine, beer and whisky. It is also used for production of industrial.spirit. Yeast can convert sugar into alcohol by a process called fermentation, which was discovered by Louis Pasture in 1857. Bacteria can also convert alcohol into acetic acid. The acetobacter can convert alcohol into acid.                  We know that all the microorganisms are not harmful. Some are useful, without which, the life would not have been possible on the earth. The microorganisms, which help to convert atmospheric nitrogen into nitrate and increase the nitrogen content of the soil is: (a) Bacillus (b) Rhizobium bacteria (c) Lactobacillus (d) Fungus (e) None of these   Answer: (b) Explanation The only bacteria, which converts atmospheric nitrogen into nitrate and increase the nitrogen content of the soil is Rhizobium bacteria.            There are some microorganisms, which decomposes the waste products and remains of dead plant and animals. This helps in keeping the environment clean. They are known as: (a) Parasitic (b) Consumer (c) Decomposer (d) Producer (e) None of these   Answer: (c) Explanation The microorganisms, which are friend to us and help us in cleaning our environment are known as decomposers.

      AIgae   They are the large group of simple plant like organisms, which contains chlorophyll and produce their food themselves. However, they are different from plants in many ways. They do not have stems, leaves and proper root system. Only some algae are unicellular and rests are multicellular. For example, diatoms and chlamydomonas are single cellular, where as blue green algae are multicellular. The blue green algae have the nitrogen fixing ability. It also known as cynobacteria. The other most common algae are red algae, brown algae, which are found in sea water.                                                                                                        Algae                Prions The prion is a proteinaous infectious particle, which is generated by organisms, modified in spongiform encephalopathies. Prions form a group of microorganisms. It is composed by protein of 250 amino- acids. So far, no accurate structure or the information is available about the prions. It could be a sort of virus.                  Some algae are unicellular and some are multicellular. Some have chlorophyll, so they can manufacture their own food. Which one of the following is a multicellular algae? (a) Diatoms (b) Chlamydomonas (c) Prions (d) Cynobacteria (e) None of these   Answer: (d) Explanation Only cynobacteria is the algae, which is multicellular and rest are unicellular.                It is a protenious microorganism, which is composed of protein of 250-amino acid. Its structure is still not estimated and is a sort of virus. Identify the organism. (a) Prions (b) Lipase (c) Plasmodium (d) Rizophous (e) None of these   Answer: (a) Explanation Prions is the algae having protenious composition and is similar to virus to some extent.

         Introduction   Microorganisms are the organisms, which are very small and cannot be seen, except with the help of microscope. They are found everywhere on the earth in air, water and land. There are different groups of microorganisms, that is, bacteria, fungi, protozoa and viruses. Microorganisms was first observed in 1674, by Van Leeuwenhoek. Although these organisms are very small, but they play very significant role to keep the life going on earth. They carry out 90% of the biochemical reactions on the earth surface, and in the atmosphere. It is believed, perhaps they are the first life forms on the earth that might have appeared. Hence they are the most common ancestors of all living being on the earth. They might have appeared 3.8 billion years ago. The first ever microorganism, that would have exist was bacilli. The discovery of the microorganisms has changed the human perception about the world. The different microorganisms are: (i) Protozoa                          (ii)  Fungi (iii) Bacteria                       (iv) Viruses              Protozoa These are the single cellular microorganisms, which have been classified as animals. They are found in ponds, lakes, drains, rivers and sea water. For example, amoeba, paramecium and entamoeba. They are parasitic in nature and causes disease like malaria and dysentery. Plasmodium is the parasite of the malaria. It is classified into four groups, on the basis of mode of locomotion or the cell organization, Protozoa's                  Fungi These are the large group of organisms, which do not have chlorophyll and depend on other for their food. They cannot manufacture their own food by the process of photosynthesis. For example, yeast, moulds, penicillium and aspergillus. They need warm and moist condition for their growth. They are normally saprophytes, which feed on dead decaying matters. But some of them are parasitic in nature and cause disease. Some of the disease caused by fungi are ringworm and athlete foot. The microscope fungi are eukaryotic cells and are used for the production of alcoholic drinks. They are also used for research in the field of biomedical and biotechnology.                                                                                                    Fungi              Bacteria The bacteria are the single cellular organisms, which are very small, having cell wall and with no defined nucleus. They are found everywhere on the earth. There are mainly three groups of bacteria, depending on their shape, that is, spherical, rod and spiral shape. The most common bacteria are lactobacillus, rhizobium, bacilli and cocci. They reproduce by binary fission and grow very rapidly in favorable conditions. Some bacteria are useful in making food like more...

       Crop Harvesting and Storage   It is the method of cutting and gathering of the matured crops from the field. It is done either manually or with the help of machines. Certain crop, like rice and wheat is harvested manually by using the cutting tools known as sickles. It can also be done by using the machines called harvesters. After harvesting, the next step is to separate the seeds from the plants, which is known as the threshing. The machine used for the threshing is known as the thresher. After threshing the chaff is separated from the grains with the help of wind and is known as winnowing. After winnowing, the grains is cleaned, dried and filled into the bags and is stored. The storage is done both traditionally and scientifically. In traditional method, it is stored in the air tight container, where no moisture is left. Before storing the grains it is dried properly, so that it is not damaged by the moulds or yeasts. Storing of food has several purposes. It helps to make stock for the scarcity or famine. It also helps to maintain the uniform supply through out the year.            Crop Improvement The demand of the food is increasing day by day due to the rapid increase in population. To meet the increasing food demand, the crop production must have to be increased. The scientific techniques are used to improve the quality, quantity and nutritional value of the food. There are various methods of crop improvements. The traditional method of crop improvement is by hybridization. In this method plants of desirable traits is breed among themselves. It can also be done by the genetic engineering, in which plants of desired traits are produces by implanting the gene of desired traits. The other methods of development of new varieties of crop in elude random change in the DNA of the plants. Genetic modification is the latest method of crop improvement. In this method, a fragment of DNA carrying the desired genetic information is planted into the identified species of the plant. It provides larger genetic pool, which helps to develop the different varieties of crops.                  In old days, harvesting was done manually. But now a days it is done in the field itself with the help of machine. The process of separating grains from the chaff and hay with the help of wind is known as: (a) Threshing (b) Harvesting (c) Gathering  (d) Winnowing (e) None of these   Answer: (d)           Arranging the following in correct order: (1) Manuring                                      (2) Sowing (3) Irrigation                                       (4) Harvesting (a) 2 --> 1 --> 3 more...

       Irrigation   It is the artificial method of supplying water for the agriculture. There are different methods of irrigations. It depends on the nature of region, where the agriculture is to be done. The different methods of irrigations are surface irrigation, localized irrigation, drip Irrigation, sprinkler irrigation, tank irrigation, canal irrigation and river irrigation.              Surface Irrigation In this method of irrigation, water moves across the land by simple gravity flow, in order to wet the soil and infiltrate into the soil. It can be further subdivided into furrow, border strip or basin irrigation. It is also called flood irrigation, as it might results in flooding the cultivated area.               Localized Irrigation It is a system where water is distributed under low pressure through a piped network, in a predetermined manner and is applied as a small discharge to each plant.                   Localized Irrigation                Drip Irrigation It is also known as trickle irrigation. Water is delivered at the roots of the plant drop by drop. It is the most efficient method of irrigation, as wastage due to the overflow or runoff is least. In modern method, drip irrigation Is often combine with plastic mulch, which further reduces evaporation and also acts as a means of delivery of fertilizer and is known as fertigation. Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long duration or delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and labour-intensive. Lower water pressures are usually needed, compared to the other types of systems, with the exception of low energy center pivot systems and surface irrigation systems. The system can be designed for uniformity throughout the field or for precise water delivery to individual plants in a landscape, containing a mixture of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available. So the field does not have to be levelled. High-tech solutions involve precisely calibrated emitters, located along lines of tubing that extend from a computerized set of valves. Both pressure regulation and filtration to remove particles are important.                                                                             Drip Irrigation                Sprinkler Irrigation In this method of irrigation, water is piped to one or more central locations within the field, where the more...

       Introduction   Agriculture is the production, processing, marketing of plants products, as foods, fibers etc. Discovery of agriculture is a mile stone in human civilisation. Present day agriculture encompasses a wide variety of specialties and techniques, which includes among other things, ways to expand the lands suitable for crop production, digging of water-channels and other forms of irrigation, fertilisation etc. There are two forms of agriculture, sustainable and intensive agriculture. The technological developments have increased the agricultural production level many folds. The major agricultural products are food, fibers, and various other raw materials for agri-based industries. But the scientific advancement, at the same time, has also created widespread ecological imbalance and negative effect on human health.            Crop Production Management The cropping systems in the farms depend on the available resources and constraints of the environmental conditions of a place. Depending on the condition, there are different types of farming. The shifting agriculture is a system, in which the forest are cut and burnt to develop land for farming. Once the land is developed, the farmers shift to the new place or exploit the new pieces of land. The period for which the plot is left uncultivated is known as the field fallow. The other methods of farming are intercropping, mixed cropping, etc. In tropical environment, all the crops are grown, but in subtropical and arid environment, the timing and extent of agriculture is limited by the rainfall. All the perennial crops, such as, coffee, tea and chocolate etc are grown in this region. Crop Production Systems                    All the living organisms need food for their survival. They derive their food from the plants or other living organisms. The organized method of production of food by the human to fulfill their requirements is called: (a) Sericulture (b) Horticulture (c) Agriculture (d) Silviculture (e) None of these   Answer: (c) Explanation The production of food crop is called agriculture.             There are different methods of agriculture. Large scale food is produced and buffer stock is created. The agriculture for the fulfillment of own requirements is called: (a) Intensive agriculture (b) Extensive agriculture (c) Sustainable agriculture (d) Horticulture (e) None of these   Answer: (c) Explanation Agriculture is done at different stages to fulfill the needs and requirements. It may be on large scale or small scale, depending on the requirement. The agriculture forthe fulfillment of minimum requirement is called sustainable agriculture.                Horticulture It is the branch of science, which deals with the cultivation and processing of crops on large scale. It is broadly divided into two categories- ornamentals and edibles plants. It has eight area of more...