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Name: Date: Auxins: Pg. 807 1. Auxin is produced by________________ and______________. 2. How does auxin move through the plant? __________________________________________________________ 3. What is the main function of this hormone? __________________________________________________________ 4. Describe how auxin effects cell elongation? __________________________________________________________ 5. What does auxin induce? __________________________________________________________ 6. How does this hormone affect fruit production? __________________________________________________________ 7. Hoe does this hormone affect flower production? __________________________________________________________ Cytokinin: Pg. 808 1. Cytokinin is produced by________________. 2. How does cytokin move through the plant? ________________________________________________________________ 3. What is the main function of this hormone? ________________________________________________________________ ________________________________________________________________ 4. How do cytokinins affect cell division? ________________________________________________________________ ________________________________________________________________ 5. How do cytokinins counteract auxin? ________________________________________________________________ ________________________________________________________________ 6. Explain how cytokinins affect senescence of organisms. ________________________________________________________________ ________________________________________________________________ Auxin moves only downward but gravity does not cause its movement. It is generally produced by apical shoot meristems and developing leaves. Auxin promotes growth by stimulating cell elongation. It triggers enzyme activities that loosen the cell wall fibers (normally tightly woven) Auxin also stimulates cell division. It activates the vascular cambium and promotes the formation of lateral roots by the pericycle. Auxin inhibits the growth of lateral buds. Inhibits roots small quantities promote root growth. Slight increases inhibit it. Auxin production by seeds stimulates fruit growth. If eggs are not fertilized, ovules do not become seeds and auxin cannot be produced. The lack of auxin results in abscission of the flower. Auxin also prevents fruits and leaves from off prematurely. It can be sprayed on to prevent from falling off. high concentration → uncontrolled growth, death example: some herbicides- 2,4-D, 2,4,5-T (components of agent orange) Cytokinins stimulate cell division major source is the roots oppose auxin by: move upward promote growth of lateral buds as plant grows, lower buds are more under the influence of cytokinins prevents leaf senescence Senescence Senescence refers to the aging and eventual death of a plant or plant parts. When plant parts senesce, nutrients are withdrawn and redistributed via the phloem. In deciduous species (species that lose their leaves), nutrients move to the stems and roots for storage.