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Plant Responses and Adaptations

Plant Responses and Adaptations. Plant Hormones. A hormone is a chemical in an organism that causes a physiological change Hormones in plants regulate growth and development. Auxins :. Cause cell elongation in apical meristems of plant stems Delay fruit formation. Gibberellins:.

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Plant Responses and Adaptations

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  1. Plant Responses and Adaptations

  2. Plant Hormones • A hormone is a chemical in an organism that causes a physiological change • Hormones in plants regulate growth and development

  3. Auxins : • Cause cell elongation in apical meristems of plant stems • Delay fruit formation

  4. Gibberellins: • Stimulate cell elongation, like auxins • Increase rate of seed germination • Farmers use gibberellins to enhance fruit formation

  5. Cytokinins: • Stimulate mitosis and cell division • Are produced in root meristems and travel up plant through xylem tissue

  6. Ethylene: • Is a gas composed of C and H, produced mostly in fruits, leaves and stems • Ripens fruits • Breakdowns complex carbs to simple sugars, making food taste sweeter

  7. Plant Tropic Responses • A tropism is a plant’s response to an external stimulus. • A tropism is POSITIVE if the plant grows TOWARD the stimulus. • A tropism is NEGATIVE if the plant grows AWAY from the stimulus. • Tropic responses are not reversible unless stimulus changes.

  8. Phototropism-response to light • Cells elongate in plant stems due to auxin hormone • Plant grows towards the light

  9. Gravitropism-response to gravity • Upward growth of stems • Downward growth of roots • Due to gravity • Beneficial to plants

  10. Thigmotropism-response to touch • Plants come into contact with an object and begin to grow around it

  11. Nastic Movement Plant movement that is not dependent on direction of a stimulus

  12. Plant Reproduction Includes sporophyte stage and gametophyte stage

  13. Alternation of Generations • Diploid sporophyte makes haploid spores through meiosis • Spores undergo mitosis and form multicellular haploid gametophyte • Gametophyte forms haploid gametes (egg and sperm) which form a zygote together • Zygote undergoes mitosis to become embryo sporophyte, which matures and cycle begins again

  14. Flower Structure • Angiosperms are plants that produce flowers • Flowers have many organs that each have a separate function

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