Chapter 16: Environmental Issues
1. What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.Ans: Domestic sewage contains four kind of impurities:(i) Suspended solids: They are soil particles such as sand and silt.(ii) Colloidal particles: They are…
Chapter 15: Biodiversity and Conservation
1. Name the three important components of biodiversity.Ans: Three components of biodiversity are:(a) Genetic diversity(b) Species diversity(c) Ecological diversity 2. How do ecologists estimate the total number of species present in the world?Ans: Ecologists estimate the total number of…
Chapter 14: Ecosystem
1. Fill in the blanks.(a) Plants are called as————- because they fix carbon dioxide.(b) In an ecosystem dominated by trees, the pyramid (of numbers) is————- type.(c) In aquatic ecosystems, the limiting factor for the productivity is————- .(d)…
Chapter 13: Organisms and Populations
1. How is diapause different from hibernation?Ans: Diapause is a period of suspended growth or development occuring in many insects and other invertebrates during which metabolic activities are greatly reduced. On the other hand, hibernation is a sleep like…
Chapter 12: Biotechnology and its Applications
1. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because –(a) bacteria are resistant to the toxin(b) toxin is immature;(c) toxin is inactive;(d) bacteria encloses toxin in a special sac.Ans: (c) Toxin…
Chapter 11: Biotechnology Principles And Processes
1. Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).Ans: (i) Human insulin – Diabetes(ii) Human growth hormone – Dwarfism cure(iii) Blood clotting factor…
Chapter 10: Microbes in Human Welfare
1. Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the…
Chapter 9: Strategies for Enhancement in Food Production
1. Explain in brief the role of animal husbandry in human welfare.Ans: Animal husbandry deals with the caring, feeding and management of domesticated animals. It includes poultry, farming and fisheries.These animals are very useful for human beings…
Chapter 8: Human Health and Disease
1.What are the various public health measures, which you would suggest as safeguard against infectious diseases?Ans. The various public health measures against infectious diseases includes the following –1.Education – People should be educated about the infectious diseases so that…
Chapter 7: Evolution
Evolution Chapter Class 12 NCERT Q1. Explain antibiotic, resistance observed in bacteria in light of Darwinian selection theory.Ans: According to Darwin, environment selects organisms with favourable variations and these organisms are allowed to survive. When a bacterial population…
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