If Canada can maintain its sovereignty over the water ways of the north what are pros and cons of this position?

a- all cells come from pre-existing cells

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.

the tricuspid valve is present between right atrium and right ventricle

bacterium is not correct