Biology:2014:[Delhi]:Set-III
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Q1
Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Marks:1View AnswerAnswer:
The type of host cell that is suitable for the gene guns to introduce an alien DNA is plant cell.
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Q2
Name any two types of cells which act as “cellular barriers” to provide innate immunity in humans.
Marks:1View AnswerAnswer:
(i) Polymorphic-nuclear leukocytes and monocytes
(ii) Macrophages
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Q3
How is repetitive/satellite DNA separated from bulk genomic DNA for various genetic experiments?
Marks:1View AnswerAnswer:
Density gradient centrifugation separates satellite DNA from bulk genomic DNA.
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Q4
Write the name of the organism that is referred to as “Terror of Bengal”.
Marks:1View AnswerAnswer:
Water hyacinth (Eichhornia crassipes) is referred to as “Terror of Bengal”.
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Q5
Name the green house gases that contribute to total global warming.
Marks:1View AnswerAnswer:
Carbon dioxide and methane are the green houses gases that contribute to total global warming.
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Q6
Identify ‘a’ and ‘b’ in the figure below representing proportionate number of major vertebrate taxa.
Marks:1View AnswerAnswer:
(a) Amphibians
(b) Mammals
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Q7
Give an example of an organism that enters ‘diapause’ and why.
Marks:1View AnswerAnswer:
Zooplanktons enter diapauses, i.e., they undergo a period of suspended development to overcome unfavourable conditions.
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Q8
How is stratification represented in a forest ecosystem?
Marks:1View AnswerAnswer:
Stratification is the vertical distribution of different species occupying different levels. In a forest, trees occupy top vertical strata or layer of a forest, shrubs the second and herbs and grasses occupy the bottom layers.
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Q9
i) Name the scientist who suggested that the genetic code should be made a combination of three nucleotides.
ii) Explain the basis on which he arrived at this conclusion.
Marks:2View AnswerAnswer:
i) George Gamow suggested that the genetic code should be made a combination of three nucleotides.
ii) He suggested that as there are only 4 bases to code for 20 standard amino acids, the code should be a combination of bases. By permutation-combination method, a code of 3 nucleotides could code for a maximum of 64 amino acids. It was discovered that 61 codons are there for amino acids and 3 codons do not code for any amino acids.
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Q10
State the disadvantage of inbreeding among cattle. How can it be overcome?
Marks:2Answer:
The disadvantage is:
Due to continued inbreeding there occurs reduced fertility and productivity. This is called inbreeding depression.To overcome this, selected animals from breeding population is mated with unrelated superior animals of the same breed.
