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Yellow Packet Notes

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M
Mrs. Sharp

Plant growth depends on both internal and external factors. Hormones are internal chemical signals that affect growth, flowering, and fruit development. The main plant hormones are auxin, gibberellins, cytokinins, abscisic acid, and ethylene. Auxin promotes cell elongation and is involved in tropic responses like phototropism. Gibberellins stimulate stem growth and seed germination. Cytokinins promote cell division and delay aging. Abscisic acid mediates stress response and promotes dormancy. Ethylene causes fruit ripening. External factors like light, gravity, temperature and moisture also influence plant growth and development.

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Plant Responses
Factors Plant growth depends on INTERNAL factors, such as HORMONES, and external factors such as… LIGHT INTENSITY GRAVITY TEMPERATURE MOISTURE LENGTH OF DAY
Hormones Any chemical produced in one part of the body that has a target elsewhere in the body Affect GROWTH, FLOWER, and FRUIT development
Hormones Examples Auxin Gibberellins Cytokinins Abscisic Acid Ethylene
Hormone - Auxin Produced in APICAL MERISTEMS Regulates growth Promotes cell elongation Also known as IAA (Indoleacetic acid)
Hormone - Auxin Tissue response depends on hormone CONCENTRATION ROOT cells are more sensitive than STEM cells
Hormone - Auxin Causes cells on darker side of the plant to grow larger than corresponding cells on the lighter side of the plant Involved in plant movement ( TROPISM )
 
Hormone - Auxin Synthetic auxins can stimulate fruit development without fertilization ( SEEDLESS fruit)
Hormone - Gibberellins Produced in YOUNG tissue Causes elongation of STEM cells and growth of LEAVES Focus on stem growth Stimulates SEED germination
Hormone – Cytokinins Produced in the ENTIRE plant Promotes MITOSIS Involved in the closure of STOMATA during dry periods Promotes DELAY OF AGING
Hormones – Abscisic Acid Produced in LEAVES Mediates the adaptation of the plant to stress Promotes DORMANCY (helpful during drought season) by inhibiting growth of BUDS and germination of SEEDS Promotes abscission of leaves & fruit
Hormones - Ethylene A GAS that promotes ripening of fruit Produced in the ENTIRE plant Causes RIPENING of fruit by softening cell walls and converting starches into sugar Promotes SENESCENCE (causes nearby fruit to ripen)
Plant Movements Tropism Nastic Movements
Tropism Growth movement towards the direction from which the stimulus strikes the plant. Takes the name of the STIMULUS Positive Growth in the direction of the stimulus Negative Growth away from the stimulus
Phototropism Response to light Stems are positively phototropic Roots are negatively phototropic
Phototropism Caused by unequal distribution of AUXIN Auxin is transported away from light therefore, there is a [ HIGHER ] away from the light, which causes CELL elongation. This “bends” the plant toward the sun. Solar Tracking Clip
More Auxin Less Auxin Animation
 
Phototropism
Thigmotropism Response to touch Climbing vines Wraps around a solid object
 
 
Gravitropism Response to gravity Roots are POSITIVELY gravitropic Stems are NEGATIVELY gravitropic
 
Chemotropism Response to a chemical Pollen tube growth toward the ovule
Hydrotropism Response to water Willow tree roots are notorious from ruining underground pipelines
 
Nastic Movements Movement that is independent of the direction of the stimulus Movement is regulated by changes in the WATER pressure of cells Animation Examples Venus Fly Trap Sun Dew
 
 
 
Photoperiodism Response to DAY LENGTH Involves a hormone called PHYTOCHROME Two forms Phytochrome Red (P r ) Phytochrome Far Red (P fr )
Photoperiodism Ratio of P r and P fr is thought to explain how a plant can CALCULATE THE LENGTH of the day (or night)
LONG Day Plants Flower when… Days are long Nights are short Occurs during the SUMMER . Examples Radishes, petunias, wheat
SHORT Day Plants Flower when… Days are short Nights are long Occurs during the SPRING & FALL Examples Goldenrods, poinsettias, soybeans
DAY-NEUTRAL Plants Do not have a critical period of day length Flower during SPRING through FALL Examples Dandelions, tomatoes, corn
 
Photoperiodism of Short-Day Plant
 
 
Phytochrome Phytochrome RED (P r ) Converts RED wavelengths of light into FAR RED wavelengths during the day Phytochrome FAR RED (P fr ) Converts FAR RED wavelengths of light into RED wavelengths of light at night
 
 
 
 
 
 

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Yellow Packet Notes

  • 2. Factors Plant growth depends on INTERNAL factors, such as HORMONES, and external factors such as… LIGHT INTENSITY GRAVITY TEMPERATURE MOISTURE LENGTH OF DAY
  • 3. Hormones Any chemical produced in one part of the body that has a target elsewhere in the body Affect GROWTH, FLOWER, and FRUIT development
  • 4. Hormones Examples Auxin Gibberellins Cytokinins Abscisic Acid Ethylene
  • 5. Hormone - Auxin Produced in APICAL MERISTEMS Regulates growth Promotes cell elongation Also known as IAA (Indoleacetic acid)
  • 6. Hormone - Auxin Tissue response depends on hormone CONCENTRATION ROOT cells are more sensitive than STEM cells
  • 7. Hormone - Auxin Causes cells on darker side of the plant to grow larger than corresponding cells on the lighter side of the plant Involved in plant movement ( TROPISM )
  • 8.  
  • 9. Hormone - Auxin Synthetic auxins can stimulate fruit development without fertilization ( SEEDLESS fruit)
  • 10. Hormone - Gibberellins Produced in YOUNG tissue Causes elongation of STEM cells and growth of LEAVES Focus on stem growth Stimulates SEED germination
  • 11. Hormone – Cytokinins Produced in the ENTIRE plant Promotes MITOSIS Involved in the closure of STOMATA during dry periods Promotes DELAY OF AGING
  • 12. Hormones – Abscisic Acid Produced in LEAVES Mediates the adaptation of the plant to stress Promotes DORMANCY (helpful during drought season) by inhibiting growth of BUDS and germination of SEEDS Promotes abscission of leaves & fruit
  • 13. Hormones - Ethylene A GAS that promotes ripening of fruit Produced in the ENTIRE plant Causes RIPENING of fruit by softening cell walls and converting starches into sugar Promotes SENESCENCE (causes nearby fruit to ripen)
  • 14. Plant Movements Tropism Nastic Movements
  • 15. Tropism Growth movement towards the direction from which the stimulus strikes the plant. Takes the name of the STIMULUS Positive Growth in the direction of the stimulus Negative Growth away from the stimulus
  • 16. Phototropism Response to light Stems are positively phototropic Roots are negatively phototropic
  • 17. Phototropism Caused by unequal distribution of AUXIN Auxin is transported away from light therefore, there is a [ HIGHER ] away from the light, which causes CELL elongation. This “bends” the plant toward the sun. Solar Tracking Clip
  • 18. More Auxin Less Auxin Animation
  • 19.  
  • 21. Thigmotropism Response to touch Climbing vines Wraps around a solid object
  • 22.  
  • 23.  
  • 24. Gravitropism Response to gravity Roots are POSITIVELY gravitropic Stems are NEGATIVELY gravitropic
  • 25.  
  • 26. Chemotropism Response to a chemical Pollen tube growth toward the ovule
  • 27. Hydrotropism Response to water Willow tree roots are notorious from ruining underground pipelines
  • 28.  
  • 29. Nastic Movements Movement that is independent of the direction of the stimulus Movement is regulated by changes in the WATER pressure of cells Animation Examples Venus Fly Trap Sun Dew
  • 30.  
  • 31.  
  • 32.  
  • 33. Photoperiodism Response to DAY LENGTH Involves a hormone called PHYTOCHROME Two forms Phytochrome Red (P r ) Phytochrome Far Red (P fr )
  • 34. Photoperiodism Ratio of P r and P fr is thought to explain how a plant can CALCULATE THE LENGTH of the day (or night)
  • 35. LONG Day Plants Flower when… Days are long Nights are short Occurs during the SUMMER . Examples Radishes, petunias, wheat
  • 36. SHORT Day Plants Flower when… Days are short Nights are long Occurs during the SPRING & FALL Examples Goldenrods, poinsettias, soybeans
  • 37. DAY-NEUTRAL Plants Do not have a critical period of day length Flower during SPRING through FALL Examples Dandelions, tomatoes, corn
  • 38.  
  • 40.  
  • 41.  
  • 42. Phytochrome Phytochrome RED (P r ) Converts RED wavelengths of light into FAR RED wavelengths during the day Phytochrome FAR RED (P fr ) Converts FAR RED wavelengths of light into RED wavelengths of light at night
  • 43.  
  • 44.  
  • 45.  
  • 46.  
  • 47.  
  • 48.