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 and skills:
- Application: Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones.
- Application: 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.
Guidance:
- Auxin is the only named hormone that is expected.
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Theory of knowledge:
- Plants communicate chemically both internally and externally. To what extent can plants be said to have language?
Utilization:
- Micropropagation is used for rapid bulking up of new varieties of plant.
- Syllabus and cross-curricular links:
- Biology
- Topic 3.5 Genetic modification and biotechnology
Aims:
- Aim 6: Investigations into tropisms could be carried out.
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