Biology:2010:CBSE:[Delhi ]:Set-I
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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
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 . -
Q3
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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Q4
Name the scientist who disproved spontaneous generation theory.
Marks:1View AnswerAnswer:
Louis Pasteur disproved the spontaneous generation theory.
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Q5
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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Q6
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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Q7
A bilobed, dithecous anther has 100 microspore mother cells per microsporangium. How many male gametophytes this anther can produce?
Marks:1View AnswerAnswer:
The anther is a four sided structure consisting of four microsporangia located at the corners, two in each lobe.
Therefore, total microspore mother cells = 4 x 100 = 400.
After meiosis 400 microspore mother cells will form:
4x400=1600
Thus, 1600 microspores or pollen grains or male gametophytes will be formed. -
Q8
If 8 individuals in a laboratory population of 80 fruitflies died in a week, then what would be the death rate for population for the said period?
Marks:1View AnswerAnswer:
Death rate = Dead flies
Total flies
= 8
80
= 0.1 -
Q9
A moss plant produces a large number of antherozoids but relatively only a few egg cells. Why?
Marks:2View AnswerAnswer:
For fertilising the egg, antherozoids need to be carried to the egg cell. Out of all the antherozoids that are produced, very few reach the egg cell. The rest either get degenerated or are diverted from the path due to water current. That is why the number of antherozoids produced by a moss plant is much higher than that of the egg cells.
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Q10
Why is the introduction of genetically engineered lymphocytes into a ADA deficiency patient not a permanent cure? Suggest a possible permanent cure.
Marks:2View AnswerAnswer:
• Lymphocytes are mortal in nature and require periodic infusion into the patient and thus, is not a permanent cure.
• A permanent cure for ADA deficiency is to introduce genes isolated from marrow cells that produce ADA into cells at early embryonic stages.
