Question numbers 12(i) to 12(iv) are based on the following text on characterization of Cell Lines: In order to analyze the growth characteristics of a particular cell type or cell line, a growth curve can be established from which one can obtain a population doubling time, a lag time, and a saturation density. A growth curve generally will show the cell population's lag phase, that is, the time it takes for the cells to recover from subculture, attach, and spread; the log phase, in which the cell 3 number begins to increase exponentially and a plateau phase, in which the growth rate slows or stops due to depletion of growth factors and nutrients.(i)  Beyond what cell concentration , saturation density is achieved ? (a)  > 104 cells /ml (b)  104 to 105 cells /ml (c)  > 105 cells /ml (d)  > 106 cells /ml(ii) There is no increase in the cell concentration in the lag phase due to the following reasons: (a)  Exhaustion of the medium. (b)  Space constraint (c)  Both “a” and “b” (d)  Acclimatization to the new environment.(iii) In which phase of growth is the specific growth rate of animal cell calculated?(a)  Log phase (b)  Lag phase (c)  Stationary phase(d)  Decline phase.(iv)  A student adds antibiotic to the animal cell culture medium and still obtains the same growth curve .The probable explanation for it will be: (a) Antibiotics add growth factors and hormones in the medium (b)  Antibiotics provide serum for the growth of animal cells. (c)  Antibiotics enhance the nutrient content of the medium. (d)  Antibiotics don’t have any affect on animal cells