BIOL120 Lecture Notes - Lecture 10: Cutin, Photosynthetically Active Radiation, Contact Angle
7 Jul 2016
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Document Summary
The challenges: staying wet when things get dry, leveraging resources. The plant epidermis: colonization of terrestrial environment required mechanisms for regulating water status, modifications to the epidermis played a critical role in achieving colonization, fossil records show that the very earliest terrestrial plants had some of these modifications. Major initial challenges: gas exchange, protection from uv damage, and water retention. Subsequent challenges: defenses against herbivores, pathogens, gamete dispersal. Two key innovations are apparent in fossil records of early land plants. One of the first cell types specified during development. Derived from the outermost layer of meristematic cells postembryonically: at the at shoot/root apical meristems. Developmentally inert: epidermal cells tend not to de-differentiate. Grafting: find that epidermal cells do no contribute to graft tissues. Is covered with a specialized outer membrane" or matrix" that modulates interactions between the plant and its environment. Fulfill the basic function of protecting the tissue layers underneath.
