1. Topic 9: Plant Science 9.3 Growth in Plants

2. 1 – Undifferentiated Cells Define differentiation. What role does differentiation play in plants?

3. Meristematic cells are cells that are capable of rapid division. ◦Apical / primary / terminal meristem – occur at the tips of stem and root and are responsible for an increase in the length of the stem and root.

4. Lateral meristem – form from cambium cells in the center of the vascular bundle and promote secondary growth. Additions of the vascular tissue increase the girth of the stem.

5. Mitosis Mitosis allows for extension in stem length and girth as well as development of leaves.

6. Growth ApicalVs.Lateral Occurs at the tip of the root and stem Position Occurs laterally between the primary xylem and phloem Product of embryonic cells Origin Cambium – left from primary growth Produces initial tissues of actively growing plants Timing Functions in older stems and roots and in woody plants from the outset Epidermis, mesophyll, primary xylem and phloem Cell products Secondary xylem and phloem and fibers Produces growth in length and height Outcome Produces growth in girth and strengthening of the stem

7. 2 - Hormones How do hormones cause change in humans? In plants?

8. Hormones Plants produce growth-regulating substances (hormones) that influence growth in the shoot apex – area of active growth.

9. Phototropism Dark – thin, weak, underdeveloped, yellow. Light – short, sturdy, fully expanded, dark green. Phototropism - is directional growth in which the direction of growth is determined by the direction of the light source.

10. Auxin 1. Auxin expels protons making the area more acidic 2. Acidity activates the breakdown of cell walls making them less rigid 3. Decreases in cell wall strength causes the central vacuole to swell on the dark side to support the cell and drives phototrophic movement.

11. Auxin Continued Influence gene expression ◦Affects cell division ◦Affects cell enlargement ◦Promotes elongation ◦Stimulates elastins Movement of auxin is unidirectional and controlled by auxin efflux pumps (shoot  root)

12. Tropisms Phototropism Chemotropism Geotropism / Gravitropism Heliotropism Thigmotropism Thermotropism Hydrotropism

13. Works Cited "Ethylene- The Fruit Ripening Hormone." UrbanAsian. N.p., 27 Feb. 2013. Web. 15 May 2015. Gregoire, Sheila. "A Line from Linda." : The Tree Canopy. N.p., 3 Nov. 2014. Web. 11 May 2015. McCormally, Kathleen. "Gravitropism." Mframe1.htm. N.p., 1997. Web. 15 May 2015. "Phases of Growth." 5_PLANT_GROWTH_AND_DEVELOPMENT. N.p., n.d. Web. 15 May 2015. Siegel, Bernie. "Q & A with Bernie – June 2, 2014." Bernie Siegel MD. N.p., 2 June 2014. Web. 11 May 2015.