1) the seeds absorb the water,expand and burst.
2)Jellies,jams and pickles have been added with preservatives to prevent rancidity or it getting spoilt.
3)The roots get bigger and bigger as they grow,lack of space or soil may be the cause of them growing out.
4)Freshwater fish cannot tolerate the salinity of the sea water,as ex-osmosis occurs.
5)Yes,they will wilt if water is not been provided.Minerals and other nutrients will be made available only if fertilizers are dissolved in the water.
6)Because of Osmosis this occurs.Water in potato is comparatively less when compared to the container having water.So due to osmosis,water diffuses into potato making it fat and big in size :P