Purebred is another word for homozygous
Ans: Cells are so small because it allows them to have a better surface area to volume ratio. This makes it much easier for the cell to bring in necessary nutreints and excrete wastes. Also the smaller the cell is, the less time it takes to replicate the small cell as opposed to a bigger cell.
The lack of access to the healthy food has caused the growth of Sebastian to slow down. In the case healthy food is provided to him, he can grow into the size he was genetically suited to. This process is known as the canalization. Canalization term is used as the measure of the ability of any given genotype to result in the same phenotype in-spite of the environmental variability.
Canada as it is far from the equator