BIO SCI 94 Lecture 9: Lecture 9

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Nancy Burley

Document Summary

Increase independence from water (evolved from freshwater algae) Sporopollenin - durable polymer, water-tight material that encases spores (& pollen) Spore - a single cell produced by meiosis that can develop into a multicellular adult. Cuticle - waxy coating on outermost cell layer. Stomata - structures on plant surface permitting gas exchange for photosynthesis - pores with guard cells. Cuticles and pores are the most key innovations fro living on land. Alternation of generations - multicellular haploid phase (gametophyte) alternates with multicellular diploid stage (sporophyte) Plants that are gametophytes through mitosis produce sporophytes, and sporophytes produce gametophytes through meiosis. Gametophyte produce gametes through mitosis, then forms zygotes then for sporophytes, then sporophytes produce spores through meiosis to form gametophytes because spores do mitosis to form the gametophytes. Audio recording started: 5:01 pm thursday, february 9, 2017. Alternation of generations evolved in common ancestor of land plants. Often resistant to desication, but need water to reproduce.