Final answer:
Bryophytes transport water and nutrients through diffusion and osmosis across their gametophyte surfaces and rely on external water for reproductive processes. They are non-tracheophyte plants that lack true vascular tissue and survive in a variety of environments, including damp habitats and the tundra.
Step-by-step explanation:
Water and nutrients are transported through bryophytes mainly through diffusion and osmosis, rather than via the specialized vascular systems like those found in higher plants. Bryophytes, which include mosses, liverworts, and hornworts, lack true roots, relying on structures called rhizoids for anchorage and some degree of water and nutrient uptake. Since they lack vessels such as the xylem and phloem, bryophytes absorb water directly over their surface when it is available. Their entire gametophyte surfaces are involved in the uptake of moisture and nutrients. Additionally, the reproductive cycle of bryophytes requires water, with flagellated sperm needing a liquid medium to reach the egg for fertilization.
Thriving in mostly damp habitats but also able to survive in deserts, bryophytes constitute the primary flora in tundra regions and other inhospitable environments due to their small size and ability to withstand desiccation. However, the lack of a cuticular layer makes bryophytes more susceptible to pollutants in rainwater, which can readily penetrate their tissues.
It's important to note that despite being commonly referred to as non-vascular plants, a more accurate term for bryophytes would be non-tracheophyte since they do possess specialized conducting cells, albeit not the lignin-reinforced cells found in vascular plants.