Final answer:
Seed plants have advantages including protection and nutrition for embryos in seeds, which allows for dormancy and survival in various conditions. Dispersal mechanisms enable seeds to travel and germinate in favorable conditions, unlike ferns and mosses that rely on water for reproductive success.
Step-by-step explanation:
Compared to ferns and mosses that have spores, seed plants like angiosperms and gymnosperms offer several advantages. One significant advantage is protection and nutrition for the developing sporophyte. Seeds contain the embryo, equipped with a substantial nutrient reserve, allowing it to survive until conditions are favorable for growth, enhancing the likelihood of successful establishment. This is a stark contrast to spores, which are single cells and do not provide such sustenance.
Another advantage of seeds is their dispersal mechanism. Seeds can remain dormant through a range of conditions, waiting to germinate when the environment becomes suitable. Moreover, with a protective coat, seeds can also withstand desiccation and delay germination until optimal growth conditions are met. Pollen, another evolutionary innovation of seed plants, enables them to reproduce without the presence of water, by transporting the male gametes to the female parts of the plant.
Overall, seeds and pollen have allowed seed plants to adapt to and thrive in diverse terrestrial environments, breaking free from the dependence on moist environments necessary for the reproductive success of ferns and mosses. The evolutionary shifts resulting in the dominance of the sporophyte generation, along with the development of pollen and seeds, have made seed plants highly successful on a global scale.