No that is just, no just no. DNA is copied through cell reproduction where a cell splits to create more (growing for multi called organisms and asexual reproduction for single celled organisms) The mitochondria is an organelle that is the "power house" of the cell, the "digestive system".
Cool front is not a standard weather front. Cold front, warm front and occluded front are all standard weather front. When you say weather front, it is a boundary that separate 2 air masses.
Radiation is the thermal energy transfer
Experiments in general are more reliable when a greater sample size is used. When using a small sample size, a mistake or fluke can greatly effect the outcome of the experiment. With a large sample size, there is more data to understand averages and deviations to the average data. The average will likely be more accurate with more data, which would make his sample size more reliable.
