Water is essential to life because it creates us humans, plants, animals, etc. So, if we find water on Mars it would be important because water is essential to life, meaning we would know that there would be some kind of life on Mars because water makes up anything.
I believe in both groups , the sperm swim from antheridia to aronia. Both are tied to water by swimming sperm that require water to reach eggs. Neither of them has pollen, seeds, flowers, or fruits. Seedless vascular plants, however, have xylem and phloem, which bryophytes lack. For seedless vascular plants Cells in diploid sporophyte such as fern from undergo meiosis, releasing haploid spores that germinate and develop into gametophytes. Bryophytes reproduce sexually by forming sperm and egg cells within separate haploid male and female gametophytes.
This is extremely vague, but assuming this is regarding concentration gradient in the nervous system, the Sodium-Potassium pump is responsible for transporting sodium and potassium.