The formular used for estimating the number of DNA copies after a particular number of cycle is 2^n, where n is the number of cycle. From the question given, number of cycle is 19. So, we have 2^19 = 524,288.
Therefore, after 19 cycles, there will be 524, 288 copies of DNA molecules.
The correct option is LOWER SALINITY.
The river Mississippi is a fresh water river which has considerably less salt than the pacific ocean which is very salty. So, at the point where the two met, the quantity of the salt there will be lower compared to the sea water of the pacific ocean.
The population may decrease due to the limiting factor - our ecosystem... which may not be able to provide sufficient food at the increasing demand...
The virus attaches to the host cells membrane