1. 9.3 Growth in Plants Understanding:
Undifferentiated cells in the meristems of plants allows indeterminate growth
Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves
Plant hormones control growth in the shoot apex
Plants respond to the environment by tropisms
Auxin influences cell growth rates by changing the pattern of gene expression
Auxin efflux pumps can set up concentration gradients of auxin in plant tissues
Applications:
Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones
Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species
Nature of science:
Developments in scientific research follow improvements in analysis and deduction: improvements in analytical techniques allowing the detection of trace amounts of substances have led to advances in the understanding of plant hormones and their effect on gene expression

2. Growth
Determinate growth: Growth stops when a certain size is reached (animals and some plants) Indeterminate growth: Growth continues (some plants)
Understanding:
Undifferentiated cells in the meristems of plants allows indeterminate growth

3. Regions of plant that grow Undifferentiated cells Active cell division
Meristems
Regions of plant that grow Undifferentiated cells Active cell division
Understanding:
Undifferentiated cells in the meristems of plants allows indeterminate growth

4. Primary growth Plant grows longer Tips of stem and roots
Apical Meristems
Primary growth Plant grows longer Tips of stem and roots
Understanding:
Undifferentiated cells in the meristems of plants allows indeterminate growth

5. Secondary growth Plant grows wider Responsible for thickness of stems
Lateral Meristems
Secondary growth Plant grows wider Responsible for thickness of stems
Understanding:
Undifferentiated cells in the meristems of plants allows indeterminate growth

6. Mitosis
Cells go through cell cycle repeatedly New cells absorb water and nutrients Increase in volume and mass After mitosis, one cell continues on into the cell cycle, one cell is used for growth
Understanding:
Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves

7. Shoot apical meristems produce cells for:
Mitosis
Shoot apical meristems produce cells for:
Continual stem growth
Flower production
Leaf production
Understanding:
Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves

8. Protoderm Procambium Ground meristem Meristems
Apical meristems can create additional meristems What do these additional meristems create?
Protoderm
Procambium
Ground meristem
Understanding:
Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves

9. Meristems
Apical meristems can create additional meristems Protoderm: Creates epidermis Procambium: Produces cambium and vascular tissue Ground meristem: Produces pith and cortex
Understanding:
Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves

11. Hormones Auxins Cytokinins Gibberellins Understanding:
Plant hormones control growth in the shoot apex

12. Hormones Auxins Growth of roots Growth of shoots Development of fruits
Leaf development
Too high concentrations = inhibits growth
Cytokinins
Produced in the root
Promote bud growth
Gibberellins
Contribute to stem elongation
Understanding:
Plant hormones control growth in the shoot apex

13. Tropisms Hormones control rate and direction of growth
Also influenced by external factors
Gravity
Light
Understanding:
Plants respond to the environment by tropisms

14. Tropisms Tropism Phototropism Geo/gravitropism Positive Negative
Growth away from the stimulus
Stimulus for growth is light
Stimulus for growth is gravity
Directional growth
Growth towards the stimulus
Understanding:
Plants respond to the environment by tropisms

15. Tropisms
Directional growth = Tropism Light = phototropism Gravity = geo/gravitropism Positive = towards stimulus Negative = away from stimulus
Understanding:
Plants respond to the environment by tropisms

16. Tropisms
Stems have positive phototropism (towards strongest light source) Stems have negative gravitropism (against gravity) Roots have positive gravitropism (with gravity)
Understanding:
Plants respond to the environment by tropisms

17. Micropropagation
What is micropropagation? What is totipotency? Describe the procedure of micropropagation What are some of the uses of micropropagation?
Applications:
Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones
Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species

18. Proteins transcribed to move auxin
Understanding:
Auxin influences cell growth rates by changing the pattern of gene expression
Proteins transcribed to move auxin
Photoreceptors (made from proteins) absorb light
These proteins bind to receptors on cells
Causes certain genes to be transcribed
Specific proteins made
(PIN3)
Proteins transport auxin from cell to cell

19. Phototropism
Auxin produced at the stem tip PIN 3 proteins move auxin to side of the stem with least light Causes cells on dark side to elongate or grow faster Gene expression in those cells altered to promote cell growth
Understanding:
Auxin influences cell growth rates by changing the pattern of gene expression

20. Phototropism
Auxin causes transport of protons from cytoplasm to cell wall (Active process – requires a proton pump) Breaks bonds in cell walls Cell walls become more flexible Cells can increase in size easily (water into vacuole)
Understanding:
Auxin efflux pumps can set up concentration gradients of auxin in plant tissues

22. Micropropagation
What is micropropagation? What is totipotency? Describe the procedure of micropropagation What are some of the uses of micropropagation?
Applications:
Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones
Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species