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19 Cards in this Set
- Front
- Back
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Plant Hormones |
-plants produce many chemicals that can alter their growth & metabolism -these are called hormones or plant growth regulators -ex. Auxin, Cytokinins, Gibberellins, Brassinosterioids, Abscisic Acid (ABA), Strigolactones, Ethylene, Florigen |
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Auxin |
-promotes stem elongation -major auxin is indoleactetic acid (IAA) -can be growth towards light (phototropism) or growth in response to gravity (gravitropism) |
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Phototropism |
-growth of a plant shoot toward or away from light |
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Gravitropism |
-growth of plant toward or against gravity -can be positive as roots go down -can be negative as shoots grow up -controlled by special dense starch-filled plastids called statoliths |
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Cytokins |
-induces & regulates cell division (cytokinesis) -common in the endosperm of a seed & in actively growing areas |
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Gibberellins |
-group of hormones that stimulate growth producing tall stems, large fruit, seed germination, etc -eater absorbed into a seed induces the embryo to release gibberellins, break from dormancy, & germinate |
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Brassinosteroids |
-group of plant hormones that promote cell division in shoots & roots, slows leaf abscission, promotes xylem formation |
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Abscission |
-leaf abscission: loss of leaves from deciduous trees to help prevent drying during times of stress -before abscission, nutrients & water are retrieved from leaves & stores for use in new leaves next season; leaves dry & change colour as their pigments break down |
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ABA |
-Abscisic acid: produced in response to water deficiency; signals guard cells to close, faciliates drought tolerance & seed formancy -ensures seeds only grow when sufficient water is present |
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Strigolactones |
-promote seed germination, attract mycorrhizal fungi |
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Ethylene |
-gaseous hormone that promotes ripening of fruit, leaf abscission, & the triple response in seedlings |
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Triple Response |
-a response of seedling to mechanical stress -includes: ---inhibition of stem elongation ---promotion of lateral expansion -horizontal growth |
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Fruit Ripening |
-immature fruits = bitter & green; helps prevents animals from eating them until inner seeds are ready -ethylene promote ripening, making fruit brightly coloured & sweet to attract animals |
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Etiolation |
-etiolation: morphological adaptation of plants to grow in the dark -de-etiolation: change of a plant shoot as it is exposed to light. Induces the plant to make chlorophyll & perform photosynthesis |
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Florigen |
-plant protein hormone that signals a bud to produce a flower |
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Photopeiodism |
-physiological plant response to a photoperiod (length of day & night). This could involve flowering |
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Circadian Rhythms |
-physiological cycle of plants & animals that consists of 24 hours, in the absence of any external environmental cues -a bean plant will still drop its leaves at midnight, even if light is still present |
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Thigmomorphogensis |
-directional growth or movement of a plant in response to touch --ex. Mimosa Pudica; venus fly trap, arabidopus |
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Defense Against Infection |
-hypersensitive response: cells & tissues die around the area of infection to limit spread; localized & specific -systemic response: infected cells release chemicals that spread through the phloem around the plants; helps the other cells to express proteins that help in defense |
