Biology:2010:CBSE:[Delhi ]:Set-III
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Q1
Mention one positive and one negative application of amniocentesis.
Marks:1View AnswerAnswer:
Positive impact: It is used for detecting foetal abnormalities or genetic diseases during pregnancy.
Negative impact: It is also used for determining the sex of foetus which leads to female foeticide. -
Q2
How do the animals like fish and snails avoid summer related unfavorable conditions?
Marks:1View AnswerAnswer:
Fishes and snails avoid summer-related unfavorable conditions by undergoing aestivation or summer sleep.
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Q3
In a pond there were 200 frogs. 40 more were born in a year. Calculate the birth rate of the population.
Marks:1View AnswerAnswer:
Birth rate = number of births
Total population
Birth rate = 40/200 = 0.2 offsprings per frog per year. -
Q4
Mention two functions of the codon AUG.
Marks:1View AnswerAnswer:
The two functions of codon AUG are:
a) It acts as an initiation or start codon and codes for formylated methionine.
b) It codes for the amino acid methionine when present in an intermediate position . -
Q5
Name a molecular diagnostic technique to detect the presence of a pathogen in its early stage of infection.
Marks:1View AnswerAnswer:
PCR (Polymerase Chain Reaction) is used to detect the presence of pathogens in the early stage of infection because it amplifies even a minute quantity of DNA.
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Q6
Name the scientist who disproved spontaneous generation theory.
Marks:1View AnswerAnswer:
Louis Pasteur disproved the spontaneous generation theory.
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Q7
What is it that prevents a child to suffer from a disease he/she is vaccinated against? Give one reason.
Marks:1View AnswerAnswer:
Specific antigens or killed/weakened micro-organisms stimulate the immune system to synthesise antibodies against that particular disease. When the same micro-organism attacks a person a second time, the synthesised antibodies fight against these micro-organisms; hence, prevents a child to suffer from that disease.
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Q8
Why is the enzyme cellulase used for isolating genetic material from plant cells but not from animal cells?
Marks:1View AnswerAnswer:
Cellulase is used to digest cellulose that is present in the cell wall of plant cells. Since animal cells lack a cell wall, no cellulose is found in them. Hence, cellulase is used for digesting and isolating genetic material from plant cells and not animal cells.
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Q9
Where does triple fusion take place in a flowering plant? Why is it so called? Mention its significance.
Marks:2View AnswerAnswer:
• Triple fusion takes place inside the embryo sac.
• It is called as triple fusion because the second male gamete fuses with the secondary diploid (2n) nucleus, producing a triploid (3n) primary endosperm nucleus.
• Triple fusion is significant as it results in the formation of endosperm. The endosperm provides nourishment to the growing embryo. -
Q10
Why certain regions have been declared as biodiversity “hot spots” by environmentalists of the world? Name any two “hot spot” regions of India.
Marks:2View AnswerAnswer:
Regions which have high species richness and also a high degree of endemism have been declared as biodiversity hot spots by the environmentalists of the world.
Two hot spot region in India are:
1. Western Ghats
2. Eastern Himalayas
