Question

8. Explain the water to land transition in plants with respect to challenges overcome related to water requirements for fertilization to occur and vascular tissue. Use bryophytes, pteridophytes (e.g., ferns), gymnosperms, and angiosperms in your answer, and be sure to describe the water issues and name the types of vascularization. Complete your answer with one specific challenge faced and overcome by animals during the water to land transition.

Answer 1

8) To successfully transit from water to land plants needed to adopt the environment of land. One of the many challenges that plants will face is that they needed structural support in the land whereas they not needed it in water as the plant is already supported by water. To provide structural support vascular tissue is necessary. For example, bryophytes that live in water don't have vascular tissue as this is not needed for structural support. Apart from this plant needed to adopt a new strategy for fertilization to occur in absence of water. In water it can reproduce asexually or sexually. For asexual reproduction, fragments separate from the plant and grow as genetically identical plants. In case of sexual reproduction, water required as a medium for fertilization to happen. To overcome water problem in the land plant uses pollen as a fertilization method. For example, gymnosperms (Produces seed) and angiosperms (Flowering plants) both use this method for fertilization. Pteridophytes (another type of vascular plants) adopted a new method to overcome fertilization problem. As they lack both flower & seeds they reproduce by dispersing spores.

Animals faces problem of osmoregulation during transition from water to land. In the water it is easier to regulate osmotic pressure through skin or any other particular organ such as gills. But in land in absence of water they needed to develop kidney as a regulator for osmotic pressure.