Q23 of 26 Page 1

Good air quality is one of the important factors for healthy life for young and old alike. Vehicular pollution is one of the major causes of deterioration of air quality in big cities.

(a) List any two ways in which you can try to bring in awareness amongst the students of your age group to reduce air pollution in your city.


(b) Why is the Government promoting use of CNG/unleaded Petrol as a fuel for public and private cars, and buses etc.? Explain.


(a) Ways in which awareness can be brought amongst the students to reduce air pollution –


• Organizing Workshops to educate students about the causes and hazards of air pollution and the ways to control it.


• Making environmental studies a compulsory part of school curriculum.


• Educating them about the various policies and acts implemented by the government to control air pollution.


• Telling them about the catalytic converters and electric precipitators and the way they work to reduce the air pollution.


(b) The Government is promoting use of CNG/unleaded Petrol as a fuel for public and private cars, and buses etc.


• The vehicles have catalytic converters to reduce the emission of poisonous gases. Catalytic converters have expensive metals like platinum-palladium and rhodium as the catalysts. The vehicles equipped with catalytic converters should use the unleaded petrol because lead in the petrol inactivates the catalysts.


• CNG burns most efficiently, unlike petrol or diesel, in the automobiles and very little of it is left un-burnt. Also CNG is cheaper than petrol and diesel. It can’t be siphoned off by thieves and adulterated like petrol and diesel.


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Describe the Secondary/Biological treatment given to the sewage water before it can be released into natural water bodies.

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(a) Explain with the help of an example each, the following interactions that arise between the organisms living in a particular habitat.

(i) Predation


(ii) Competition


(b) “Evolution of ‘mutualists’ is tightly linked.” Justify with the help of an example.


OR


How does the primary succession occur and progress in a newly created pond? Give one example each of the plants appearing at different stages of succession. What would you call this type of succession?


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(a) “The female gametophyte of an angiosperm is a seven celled, eight nuclei containing structure. ” Justify.

(b) Explain double fertilization in angiosperms.


OR


(a) Differentiate between spermatogenesis and oogenesis in humans with respect to:


(i) time of their initiation; (ii) number of gametes produced by each primary spermatocyte or primary oocyte; (iii) size of the gametes produced.


(b) Write the role of F.S.H. and L.H. in regulation of spermatogenesis and oogenesis.