Q26 of 43 Page 1

(a) Differentiate between active and passive immunity.

(b) Comment on the role of vaccination and immunization in keeping human population healthy.


OR


Describe the process of secondary treatment given to municipal waste water (sewage) before it can be released into fresh waterbodies. Mention another benefit provided by this process.


a)



b) Role of Vaccination


• Antibodies produced in body against antigen neutralize the pathogenic agents.


• Vaccines also generate memory cell ( B and T cells) that recognize quickly on subsequent exposure and controls growth of pathogen with massive production of antibodies.


• Preformed antibodies or antitoxin protect our body from deadly microbes like tetanus and against snake venom.


OR


Process of secondary treatment:


1. Passing of primary effluent into large aeration tank which is constantly agitated mechanically & air is pumped into it that allows vigorous growth of useful aerobic microbes into flocs.


2. Microbes consume major part of organic matter in effluent which significantly reduces BOD.


3. Now effluent is passed into settling tank where flocs are allowed to settle/ sediment called activated sludge.


4. Digestion of activated sludge by anaerobic microbes and effluents from secondary treatment can be released into river/ stream.


5. Resulted in production of Bio gas (CH4, H2S and CO2) which can be used as source of energy.


More from this chapter

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24

Analyse the effects of ‘Alien species invasion’ on the biodiversity of a given area. Provide two examples.

 25

Mendel crossed a homozygous pea plant having yellow and round seeds with another pea plant bearing green and wrinkled seeds. He found that in some of the F2 population new combination of parental characters were observed. How will you explain the appearance of a new combination of parental characters in F2-offsprings? Support your answer with the help of Punnett square.

OR


Describe S.L. Miller’s experiment. Comment on the observations he made and his contribution towards the origin of life on Earth.


 27

A plastic sack manufacturer in Bengaluru, Ahmed Khan has managed to find an ideal solution to the problem of plastic waste. Explain in five steps the efforts of Ahmed Khan to meet the challenges of solid waste management.

OR


(a) What does an ecological pyramid represent? State any two limitations that these pyramids have.


(b) Describe an inverted pyramid of biomass with the help of an example.


 5

Name the pioneer species that invade in primary succession on bare rock and in water.