In terms of alternation of generations, this is where there is an alternation of haploid sporeophyte production and diploid gametophyte production.  On the gametophyte side, the process of meiosis is used, which produces the release of spores with a haploid chromosome count.  On the sporophyte side, mitosis is used, which produces gametes, each having a haploid chromosome count.  When the gametes combine, a diploid chromosome count occurs. 

Vascular tissue may be thought of as a series of pipes or tubes through which water and nutrients may be piped up through the main stem of the gymnosperm.  The tubes are called xylem and phloem, and there are other types of vascular tissue as well.  The main purpose of the vascular system in plants is to pump water and nutrients from the soil up through the stem of the plant so the plant will be able to manufacture its own food through the process of photosynthesis.