Tropism - Structure and Function of Plants - Lecture Notes, Study notes of Biology

Download Tropism - Structure and Function of Plants - Lecture Notes and more Study notes Biology in PDF only on Docsity! Physiology 1. Tropism - A growth response involving bending or curving of a plant toward or away from an external stimulus. 2. Phototropism - the curving of stem, petioles, leaf blades, etc toward light a. The role of auxin in phototropism – Went’s experiment with grass shoot tips and agar b. Briggs continued more in-depth experiments identifying that the controlling substance (Auxin) – is laterally transferred toward the shaded sided of the stem. c. Illustrating the action of Auxin on cell elongation (not cell division!). 3. Gravitropism a. Response relative to gravity (toward or away). b. Illustration of stem response to gravity via auxin c. Coleus shoot gravitropism response video d. Amyloplasts and gravity – focusing on the root  Act as “weights” that indicate “down” – primary sensing area is in the root cap below the root apical meristem. e. Action of Auxins in the root – these are the opposite to the action in the stem  Auxin inhibits cell elongation in roots but promotes it in stems! f. Amyloplast mutants – cannot produce amyloplasts and they cannot respond normally to gravity. g. Cytokinin also acts on the roots – illustrated on the board Docsity.com