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15 Cards in this Set
- Front
- Back
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Gibberellic Acid
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seed germination, bud germination, stem elongation, flowering/fruiting
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Auxin
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Apical dominance, phototropism, stem/cell elongation, gravitropism
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Cytokinins
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promote cell division and lateral bud outgrowth, inhibit leaf senescence
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Brassinosteroids
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Steroid hormone
Supports growth of xylem Supports elongation of stems and pollen tubes Inhibits leaf abscission |
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Abscisic acid
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– Inhibits growth/stem elongation
– Supports seed dormancy – Inhibits seed germination –Closure of stomata in response to water stress |
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Ethylene
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– Promotes fruit ripening
– Promotes leaf abscission – Promotes senescence – Inhibits stem elongation – Inhibits gravitropism |
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Hormones that Respond to Tissue Damage and Trigger
Plant Defenses |
• oligosaccharins
• jasmonates • systemin • salicylic acid |
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Phytochemical repel herbivores/microbes
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– Oils from variety of herbs & spices repel insects
– Pine sap inhibits insect pests (e.g., bark beetles) – Tannins & resins concentrate in heartwood of trees to prevent insect & microbial infestation and rotting – Many alkaloids (e.g., caffeine, nicotine, morphine, and cocaine) repel herbivores & microbes |
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Barriers to Entry:
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• Cuticle: matrix of cross-linked
lipid molecules impregnated with extremely long-chained lipids • Spines, thorns, & prickles |
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Photosynthesis
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• Occurs in chloroplasts in green plant tissues
• Leaf parenchyma cells contain 40-50 chloroplasts • Chlorophyll pigments in plants • convert energy from sunlight to chemical energy in the form of ATP & NADPH (an electron carrier) • Carotenoids (carotene and xanthophylls): absorb wavelengths of light that are not absorbed by chlorophyll and extend the range of wavelengths that can drive photosynthesis |
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Photosynthesis
Equation |
6CO2 + 12H2O + light energy =>
C6H12O6 (glucose) + 6O2 + 6H2 |
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Gas exchange
between atmosphere and plant via stomata in leaves |
Stoma (stomata plural): guard cells & pores
Guard cells: pair of bean-shaped cells Pore: opening between guard cells |
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Gas exchange between atmosphere & plant
via stomata in leaves |
• O2 produced by plant released out of stomata pores into
atmosphere where it is available for humans & animals to breath • H2O released out of the pores via evapo-transpiration • in some species (e.g., coastal redwoods & Douglas Firs) during high fog conditions, H2O can be absorbed from the air into the leaf through the stomata pores to provide H2O for the plant • During photosynthesis when CO2 levels within leaf fall below optimal levels, the stomata open & CO2 diffuses in from atmosphere |
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Sugar produced by photosynthetic organisms => fuels cellular respiration and growth of plant
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• sugars are typically stored in the form of starch (long
chains of glucose molecules) • transported in the form of the disaccharide, sucrose (glucose attached to fructose) or monosaccharide (glucose or fructose) |
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Plant Pigments & Photosynthesis
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Carotenoids
–Carotenes (e.g., beta-carotene in carrots; lycopene in tomatoes) –Xanthophylls (e.g, zeaxanthin which gives corn yellow color) Carotenoids in chloroplasts –extend range of wavelengths that drive photosynthesis –Protect chlorophyll by acting as anti-oxidant and destroy free radicals that damage the chlorophyll molecules beta-carotene also works a beneficial antioxidant in humans) During most of year the carotenoids are not visible in the leaves because the chlorophyll pigments cover them up. In fall, as the deciduous leaves are beginning to die, chlorophyll degenerates and the red, orange, and yellow carotenoids become visible |
