Hormones• Hormones are chemical substances that  control a plant’s patterns of growth,  development, and responses to  env...
Cont.• Auxins are responsible for the plant  response called gravitropsim and  phototropism• Auxins are also responsible f...
Cont.• Gibberelinns cause an increase in overall  size of plants and individual plant  structures• Ethylene is produced in...
Plant Response•   Tropism – response to external stimuli•   3 types:•   Gravitropism – responds to force of gravity•   Pho...
Cont.• Photoperiodism: seasonal activity like  flowering and growth (phytochrome is  plant pigment responsible)• Dormancy:...
Plant Adaptations• Aquatic plants: for sufficient oxygen  absorption, aquatic plants have tissues  with large air-filled s...
Cont.• Nutritional specialists: specialized features  for obtaining nutrients (carnivorous or  parasites)• Chemical: manuf...
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Plants ch 25

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Plants ch 25

  1. 1. Hormones• Hormones are chemical substances that control a plant’s patterns of growth, development, and responses to environment conditions• Auxins are produced in the apical meristem and are transported downward into the rest of the plant, stimulates cell elongation
  2. 2. Cont.• Auxins are responsible for the plant response called gravitropsim and phototropism• Auxins are also responsible for lateral buds (branches)• Cytokinins are plant hormones that stimulate cell division and the growth of lateral buds and cause dormant seeds to sprout
  3. 3. Cont.• Gibberelinns cause an increase in overall size of plants and individual plant structures• Ethylene is produced in response to auxins, fruit tissue release small amounts of the hormone which stimulates fruit to ripen
  4. 4. Plant Response• Tropism – response to external stimuli• 3 types:• Gravitropism – responds to force of gravity• Phototropism: response to light• Thignotropism: response to touch
  5. 5. Cont.• Photoperiodism: seasonal activity like flowering and growth (phytochrome is plant pigment responsible)• Dormancy: in winter, deciduous plants turn off photosynthetic pathways, transport materials from leaves to roots, and seal leaves off from the rest of the plant
  6. 6. Plant Adaptations• Aquatic plants: for sufficient oxygen absorption, aquatic plants have tissues with large air-filled spaces through which oxygen can diffuse• Desert: extensive root systems, reduces leaves, thick stems that can store water (xerophytes)
  7. 7. Cont.• Nutritional specialists: specialized features for obtaining nutrients (carnivorous or parasites)• Chemical: manufacture compounds that are toxic to predators
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