Class 12th Biology 2014 Set2 Delhi Board Paper Solution
Question 3
Give an example of an organism that enters 'diapause' and why.
Answer
Bombyx mori (silk moth) is an insect that enters diapause. It enters into diapause due to some adverse environmental conditions such as drought, extreme temperature, reduced food availability; which, in turn, delays the overall development. The physiological and metabolic activities are also diminished at this particular time. Thus, it is a type of survival mechanism exhibited by the insect at the time of adversity.
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(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals. - Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
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- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- Explain the Law of Dominance using a monohybrid cross.
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Explain the following terms with example
(a) Co-dominance
(b) Incomplete dominance - Q:- Differentiate between the followings:
(a) Repetitive DNA and Satellite DNA
(b) mRNA and tRNA
(c) Template strand and Coding strand - Q:- List two essential roles of ribosome during translation.
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(a) MALT
(b) CMI
(c) AIDS
(d) NACO
(e) HIV - Q:- What are the major components of seminal plasma?
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- Q:- 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) Common detritivores in our ecosystem are_________.
(e) The major reservoir of carbon on earth is_________. - Q:- Explain (in one or two lines) the function of the followings:
(a) Promoter
(b) tRNA
(c) Exons