1. 9.3 Growth in Plants

2. Plant hormones: Respond to changes in the environment Regulate growth
Regulate reproduction and flowering
Regulate water loss
Regulate growth by controlling mitosis and cell division

3. Meristem Tissue
Undifferentiated tissues that become many different types of tissues
Located where plants exhibit major growth

4. 2 types of Meristems Apical Meristems Lateral Meristems
Located at the top and the root of plants
Allows for growth of new leaves and flowers
Allows roots to grow down into the soil
Elongation of plant
Lateral Meristems
Responsible for secondary growth in woody plants
Allows them to increase stem and root thickness

5. Indeterminate Growth
Animal embryos have a fixed number of parts that will develop and are considered determinate growth
2 legs, 2 arms, 10 fingers/toes etc.
The growth in plants is much different and is considered to be INDETERMINATE.
Meaning apical meristems can continue to increase the lengths of stem and root throughout the life of a plant and can produce any number of extra branches of the stem or root. They can also produce any number of extra leaves or flowers.

6. Mitosis and Cell Division
Occur in the shoot apex
Provide cells needed for extension of the stem at that location
Also important for development of leaves.

8. Tropisms
A directional movement in plants in response to a stimulus

9. Type of Tropism
Response
Phototropism
Response to light
Gravitropism
Response to gravity
Thigmotropism
Response to touch
Thermotropism
Response to temperature
Chemotropism
Response to substance
Hydrotropism
Response to water

10. Auxin (plant hormone) Responsible for phototropism
Affects cells on the dark side of the plant
causes the cells away from light to elongate
When light shines directly down on a plant shoot auxin is equally distributed this causes the plant to grow straight
This hormone is released in abundance of blue light in the shoot tip.

12. Auxin
Auxin efflux pumps can set up concentration gradients of auxin in plant tissue.
Moves Auxin from cytoplasm to cell wall
Lower concentration on light side and higher concentration on dark side.
Auxin influences cell growth by changing the pattern of gene expression.
These genes cause secretion of H+ ions into cell walls that loosen connections in the cellulose fibers that allow cells to expand.

14. Micropropogation of plants
The practice of rapidly multiplying stock plant material to produce a large number of plants, using modern plant tissue culture methods.
Can create virus-free strains of existing plants
Can propagate rare species - Orchids
Uses tissue from shoot apex, nutrient agar gels and growth hormones
Used in plants to increase population faster than seeding time would allow
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