Public all over India is very much concerned about the deteriora

Subject

Biology

Class

CBSE Class 12

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

21.

Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.

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22.

In situ conservation can help endangered / threatened species. Justify the statement.

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 Multiple Choice QuestionsLong Answer Type

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23.

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organised an awareness programme entitled ‘Bury not burn’. They invited you, being a biology student to participate.
(a) How would you justify your arguments that promote burying and discourage burning?
(Give two reasons)
(b) With the help of flow charts, one for each practice, depict the chain of events that follow.


(a) Following arguments can be put forward to promote burying and discourage burning:
(i) When we burn wastes, pollutants such as carbon dioxide,NO2 , SO2 , etc. are released in the atmosphere. These
pollutants damage the environment. Due to burning, smoke is released into atmosphere which causes
problems like asthma, emphysema, etc.
(ii) Burying the waste does not have any harmful effect in fact when we bury organic wastes, the soil becomes
enriched with nutrients.
(b) The solid wastes are of two types:
Biodegradable wastes These can be degraded by the microbes, e.g. organic waster paper, etc.
Non-biodegradable wastes These cannot be degraded by the microbes and can remain as such for long periods,
e.g. plastic.
Flow charts depicting effects of burying and burning are:

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24.

(a) Arrange the following hormones in the sequence of their secretion in a pregnant woman.
(b) Mention their source and the function they perform.

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25.

State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.

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26.

Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.

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