Essential Idea:
Plants adapt their growth
to environmental conditions
Understandings:
- Undifferentiated cells in the meristems of plants allow 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
- Plant shoots respond to the environment by tropisms
- Auxin efflux pumps can set up concentration gradients of auxin in plant tissue
- Auxin influences cell growth rates by changing the pattern of gene expression
Applications:
- Micropropagation of plants using tissues 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