9.3
growth in plants
Essential Idea: Plants adapt their growth to environmental conditions.
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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.
UNDERSTANDINGS:
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Undifferentiated cells in the meristems of plants allow indeterminate growth.
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Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves.
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Plant hormones control growth in the shoot apex.
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Plant shoots respond to the environment by tropisms.
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Auxin efflux pumps can set up concentration gradients of auxin in plant tissue.
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Auxin influences cell growth rates by changing the pattern of gene expression.
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APPLICATIONS & SKILLS
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Application: Micropropagation of plants using tissue from the shoot apex, nutrient agar gels, and growth hormones.
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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.
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RESOURCES
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