Complex sentence: Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle, which means they spend most of their life cycle with diploid cells, while the gametophyte (gamete-bearing phase) is relatively short-lived.
Split into simpler sentences: Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle. The gametophyte (gamete-bearing phase) is relatively short-lived.