Plant Responses
- Created by: Sad Crab
- Created on: 01-02-21 10:47
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- Plant Responses
- Environmental Stimuli
- Abiotic
- Gravity
- Wind
- Water/ Humidity
- Light
- Temperature
- Nutrients
- Biotic
- Herbivores
- Prey
- Competition
- Pathogens
- Abiotic
- Tropisms
- Phototropism
- shoots grow towards light
- phototropic signal is auxin
- diffuses down the shoot
- promotes active transport of H+ into the cell wall
- lowers pH, allows expansin enzymes to break bonds between pectin and cellulose fibrils
- this allows the cell to stretch and expand
- lowers pH, allows expansin enzymes to break bonds between pectin and cellulose fibrils
- promotes active transport of H+ into the cell wall
- diffuses down the shoot
- Geotropism
- roots grow towards gravity
- low [auxin] = increased root growth
- Chemotropism
- growing towards chemical signals
- e.g. pollen tubes responding to chemicals to reach female ovule
- Thigmotropism
- climbing plants respond to touch
- Hydrotopism
- roots grow towards water
- Phototropism
- Responses to Herbivory
- tannins
- toxic to microorganisms and herbivores
- alkaloids
- act as deterrents
- e.g. nicotine, caffeine, morphine
- pheromones
- chemicals that alter an animal's behaviour
- tannins
- Plant Hormones
- Auxin
- apical dominance
- inhibit leaf abscission
- inhibit ethene
- Phototropism
- shoots grow towards light
- phototropic signal is auxin
- diffuses down the shoot
- promotes active transport of H+ into the cell wall
- lowers pH, allows expansin enzymes to break bonds between pectin and cellulose fibrils
- this allows the cell to stretch and expand
- lowers pH, allows expansin enzymes to break bonds between pectin and cellulose fibrils
- promotes active transport of H+ into the cell wall
- diffuses down the shoot
- Gibberellins
- promote seed germination
- seed absorbs water
- embryo releases G
- G diffuses to aleurone layer
- starts cascade of enzyme controlled reactions to synthesise amylase
- metabolises starch reserves
- uses glucose for ATP for germination
- metabolises starch reserves
- starts cascade of enzyme controlled reactions to synthesise amylase
- G diffuses to aleurone layer
- embryo releases G
- seed absorbs water
- promote internodal elongation
- promote lateral growth
- promote seed germination
- Cytokinin
- promote cell division (meristem)
- overcome apical dominance
- auxin acts as a sink for cytokinin
- promotes vertical growth
- Abscisic Acid
- inhibits gibberellins
- cause stomata to close
- Ethene
- promote fruit ripening
- promote leaf abscission
- promote senescence of plant tissue
- Auxin
- Environmental Stimuli
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