Biology 1201A Lecture Notes - Lecture 10: Cotyledon, Sieve Tube Element, Stoma
2 Oct 2016
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Seed plants: include gymnosperms (conifers) and angiosperms (flowering plants). Angiosperms are divided into two groups: dicotyledons (dicots) and monocotyledons (monocots). Storage tissue that provides nutrition to developing seedling. Numbers of petals, sepals, stamens, and other parts. Arrangement of vascular tissue (xylem + phloem) in stems. Cell are dead at maturity (no cellular component). Tracheids: long and tapered where water passes from one to another through pits. Vessel elements: shorter and wider, have less or no taper at ends. A column of vessel elements (members) is called a vessel. Perforations are where h2o passes through from one vessel member to the next (lack both 1st and 2nd cell wall). Perforations are an advantage to tracheids. b. phloem: transport sugar. Made of cells called sieve-tube members (elements) that form fluid-conducting columns (sieve tubes); living at maturity although lack nuclei and ribosomes. Pores on end of member form sieve plates (areas where cytoplasm of one cell makes contact with next cell).
