Plant Hormones Answers

Plant Hormones Handout: Student Name: ___________________________ Plant Hormones Worksheet Teacher: ________________________________ Date: ___________ Period: _________________ Plant Hormones Fill in the blank spaces with the appropriate definition or description of each. What is a plant HORMONE? A naturally-occurring compound that causes change in physiology, growth or development in the plant. 1. ___AUXIN_____ Role of Hormone Cell elongation (increase cell size) Site of Production Shoot Tips Effect of Hormone Growth of plant in response to the environment, production of roots. Define and draw some examples of TROPISM: Tropism: a plant’s response to environment Phototropism- response to light Geotropism-response to gravity Thigmotropism-response to touch 2. ___CYTOKININ____ Role of Hormone Cell division (increase cell quantity) Site of Production Root Tips Effect of Hormone Mitosis of new cells; stimulates seed germination and new shoot growth Draw some examples of how this hormone works: 3. ____GIBBERELLIN___ Role of Hormone Internode elongation Site of Production Root and Shoot Tips Effect of Hormone Controls yearly cycles (flowering, seeding and dormancy exiting) rapid growth of stems and seeds. Describe how PHOTOPERIOD helps gibberellin in the plant control yearly cycles: Photoperiod: a plant’s recognition of daylight length in a 24 hour period As daylight increases in the spring, the plant recognizes a longer photoperiod. Gibberellin triggers the plant to exit dormancy. 4. ____ABSCISIC ACID______ Role of Hormone Dormancy Site of Production Chloroplasts Effect of Hormone Enters dormancy: (leaves drop off of trees, seeds fall, stomatas close to reduce water loss) Describe how abscisic acid, in the plant, enters dormancy during times of drought: In times of water stress, the chloroplasts trigger stomatas to close to prevent loss of water during respiration. 5. ____ETHYLENE_______ Role of Hormone Ripening and death Site of Production Ripening fruit, aging flowers, germinating seeds and wounded tissues Effect of Hormone Stimulates fruits to ripen, flowers to enter senescence (to grow old and die) Describe how ethylene can affect other plants: Ethylene is in gas form and can diffuse and affect nearby plants.