Biology:2010:CBSE:[Delhi ]:Set-II
To Access the full content, Please Purchase
-
Q1
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 . -
Q2
Name the scientist who disproved spontaneous generation theory.
Marks:1View AnswerAnswer:
Louis Pasteur disproved the spontaneous generation theory.
-
Q3
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.
-
Q4
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.
-
Q5
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. -
Q6
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 -
Q7
An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give one reason.
Marks:1View AnswerAnswer:
An anther with malfunctioning tapetum fails to produce viable male gametophytes because it is unable to nourish the developing pollen grains.
-
Q8
In a pond, there are 20 hydrilla plants. Through reproduction 10 new hydrilla plants were added in a year. Calculate the birth rate of the population.
Marks:1View AnswerAnswer:
Birth rate = number of births
Total population
Birth rate = 10/20 = 0.5 off springs per hydrilla per year. -
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
Name the type of food chains responsible for the flow of larger fraction of energy in an aquatic and a terrestrial ecosystem respectively. Mention one difference between the two food chains.
Marks:2View AnswerAnswer:
• The food chain responsible for the larger flow of energy in an aquatic ecosystem is the grazing food chain (plankton food chain). On the other hand, for terrestrial ecosystem it is the detritus food chain.
• The grazing food chain begins with producer and continues to primary and secondary consumers. However, the detritus food chain begins with dead organic matter and is made up of decomposers mainly fungi and bacteria.
