1. Explain the role of microbes in Household products.
Ans. We use microbes or products derived from them everyday. A common example is the production of curd from milk.Micro-organisms such as lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it to
curd. During growth the LAB produce acids that coagulate and partially digest the milk proteins. A small amount of curd added to the fresh milk as inoculum or starter contains millions of LAB, which at suitable temperatures multiply, thus converting
milk to curd, which also improves its nutritional quality by increasing vit. B12. In our stomach too, the LAB play very beneficial role in checking disease causing microbes. [2/2] The dough, which is used for making foods such as dosa and idli is also fermented by bacteria. The puffed-up appearance of dough is due to the production of CO₂ gas. Similarily, the dough, which is used for making bread is fermented using baker’s yeast (saccharomyces cerevisiae). A number of traditional drinks and foods are also made by the microbes.
2. What is transgenic plant ? Mention in brief about Pest resistant (Bt) Cotton plants.
Ans. The plants produced through genetic engineering contain genes usually from an unrelated organism. Such genes are called transgenes and the plants having transgenes are called transgenic plants.
There is a soil bacterium Bacillus thuringiensis which produces proteins to kill certain insects. These toxic proteins crystals are called insecticidal proteins. It also named as Bt toxin proteins. Bt toxin proteins exist as inactive protoxins but once an insect ingests the inactive toxin, it is converted into an active form of toxin. The activated toxin binds to the surface of midgut epithelial cells and create pores, which eventually leads to death of the insect.
Such specific Bt toxin genes are isolated from Bacillus thuringiensis and incorporated into several crops such as cotton. The choice of gene depends upon the crop and the targeted pest. Toxin is coded by a gene named Cry.
3. Give an account of Ecological succession.
Ans. The gradual and fairly predictable change in the species composition of a given area is called ecological succession. During succession some species colonise an area and their populations become more numerous, where as population of other species decline and even disappear. The entire sequence of communities that successively change in a given area are called Sere. The Present day communities in the world have come to an end because of succession that has occured over millions of years since life started on earth.
Succession is hence process that starts where no living organisms are there. These could be areas where no living organisms ever existed, say bare rock, or in areas that some how, lost all the living organisms that existed there. The former is called primary succession while the latter is termed as secondary succession.
4. Give an account of Pyramid of biomass.
Ans. In most of ecosystems, all pyramids of biomass are situated above the base, i.e. number of producers and biomass is more than herbivores. Similarly, the number of herbivores and biomass is relatively more than biomass of carnivores, But in ocean, the biomass is more .
5. What is ecosystem? Give an a/c of Energy flow in an ecosytem.
Ans. There is formation of ecosystem by collaboration with various components of environment and exchange of materials between energy and materials. Thus, ecosytem is an autotrophic structural and functional unit of environment. It depends completely on sun for the energy.
Energy flow in an Ecosystem-
In any ecosystem the storage and flow of energy is based upon the law of thermodynamics. According to its first law, there is neither production nor loss of energy but there is always transformation of energy from one component to the other. The flow of energy in any ecosystem is in the form of food. It is due to decomposition of food energy as heat. Due to metabolic activities organism occupy a place in the natural surroundings or in a community according to their feeding relationship with other organisms. Based on the source of their nutrition or food, organisms occupy a specific place in the food chain, called trophic level.
6. What is Ozone depletion? Mention its effect & prevention.
Ans. Ultraviolet rays present in Sunlight are harmful to organisms which is protected by ozone layer. This is present in atmospheric Stratosphere in between 16-50 km height in the form of protective covering and protects against the ill-effect of uv-radiations causing skin cancer, cataract, etc.
Ozone formation takes place by the action of ultraviolet rays on molecular oxygen.
In modern life-style some useful chemicals like Fluorocarbon (FC), chlorofluorocarbon (CFC) etc. reacts with ozone to decompose into molecular (0₂) and atomic (0) oxygen to make ozone depletion. This is called ozone hole. It was first studied by scientists in south pole or Antarctica. To decrease such ozone depletion, there is effort in various parts of the world to stop the use of CFC completely. In 1987 in Montreal (Canada), there was an international summit in support of this called Montreal protocol.
7. What is nuclear wastes, write a note on disposal of it.
Ans. Waste materials disposed from nuclear instruments are called nuclear wastes. Those such wastes which have less radiation are disposed into sewage while with high radiations can be treated specially alongwith storage & disposal. Radionuclids are separated by precipitation. Solid and concentrated radioactive wastes are specially collected in tanks made up of concrete & steel. They are filled safely and sealed further. Some concentrated radioactive wastes are used in making ceramic, glass or concrete like solid substances. Those wastes which have higher half-life period can not be disposed totally. [5]
8. Write a note on Air Pollution, its effect and control.
Ans. Air pollution is the addition of materials or chemicals into atmosphere in such concentration that they begin to exert adverse effect on human beings. Such chemicals are called Air
pollutants, e.g. Smoke, Dusts, Gases like CO, CO₂, SO, etc. [2] Effects of Air Pollution: Air pollution is highly detrimental to human beings, growth and development of plants, natural resources, etc. Detrimental effects depend upon the concentration of air pollutants.
09. Write a note on Tiger Project.
Ans. ‘Project Tiger’ or Tiger Project is the symbol to honour the tiger because tiger is the indication of bio-diversity in Indian subcontinent. Tiger Project is the project governed by Government of India with the main objective to care after of tiger to maintain the number. Such place where there is natural collection and coservation of tiger is called Tiger reserve. At present the no. of such tiger reserve is 25 which was previously 9. There is enhancement in the number of tiger due to the creation of such tiger reserve.
At present the total number of tiger (data based on 2006)is approximately 50,000.
10. Mention any two levels of biodiversity in the biosphere.
Ans. Two main levels of biodiversity in the biosphere are-
(a) Species diversity-It occurs at the species level. e.g. The Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
(b) Ecological diversity-It is at the ecosystem level. e.g. India for instance with its deserts, rain forests, mangroves, coral reefs, wetlands, etc. has a greater ecosystem diversity than a Scandinavian country like Norway.
