Used to prevent leaf and fruit drop and to promote flowering for flower production. In high concentrations, auxin can promote fruit drop, useful when too many small fruits are produced as larger, fewer plants will be grown.
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How does auxin relate to taking cuttings?
Dipping the end of a cutting in rooting powder before planting, encourages root growth. Rooting powder contains auxins, fungicides and talcum powder.
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How can auxin alter seedless fruit?
Treating unpollinated flowers with auxin can promote growth of seedless fruit. Auxin promotes ovule growth which triggers automatic production of auxin by tissues in the developing fruit.
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How can auxin be used as a herbicide?
To kill weeds. Transported in the phloem to all parts of the plant+can act within the plant for longer because they are not a close fit to the enzymes that break them down. They promote shoot growth so much that the plant can't support itself+dies.
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Explain gibberellins and fruit production
Gibberellins delay fruit senescene in citrus fruit, extending time fruit can be left unpicked+in shops.Gibberellins acting with cytokinins=apples elongate improving their shape.No gibberellins=grapes grow restricted, with gibberellins grapes=bigger.
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Describe effect of gibberellins on brewing
When barley seeds germinate, aleurone layer of seed makes amylase enzymes that break down starch to amylase.Genes for amylase production switched on naturally by gibberellins. Adding it speeds up process. Malt produced by drying+grinding seeds.
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Effect of gibberellins on sugar production
Spraying sugar cane with gibberellins stimulates growth between nodes, elongating stems.Useful as sugar cane stores in cells of internodes making more sugar available.Spraying increases sugar yield.
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Effect of gibberellins on plant breeding
Plant breeder produces plants with desired characteristics.Conifer take long time as spend a lot of time as juvenilles. Gibberellins speed up by inducing seed formation.Harvesting biennial plants adds gibberellins to induce seed production in year 1.
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Why can stopping plants from making gibberellins be useful?
Spraying gibberellin synthesis inhibitors keeps flowers short+stocky+ensures internodes of crop plants stay short to prevent lodging. Lodging happens in wet summers-stems bend over due to water weight on seed heads making it difficult to harvest.
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What are cytokinins used for and why?
Used to prevent yellowing of lettuce leaves after they have been picked, because they can delay leaf senescene.
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Why are cytokinins used in tissue culture?
To help to mass-produce plants.
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What do cytokinins do and what effect does this have on a plant?
They promote bud and shoot growth from small pieces of tissue taken from a parent plant. This produces a short shoot with a lot of side branches that can be split into many smaller plants which can then be grown separately.
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What have scientists developed around ethene and how is it applied?
2-chloroethylphophonic acid. Sprayed in solution. It is easily absorbed and slowly releases ethene inside the plant.
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What are some commercial uses of ethene?
Speeding up fruit ripening, promoting fruit drop, promoting female sex expression, promoting lateral growth.
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Why can restricting ethene's effects be useful?
Storing fruit in low temp with little oxygen and high CO2 conc prevents ethene synthesis and fruit ripening. Makes fruit last longer. Silver salts (inhibitor of ethene synthesis) can increase shelf life of cut flowers.
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Other cards in this set
Card 2
Front
How does auxin relate to taking cuttings?
Back
Dipping the end of a cutting in rooting powder before planting, encourages root growth. Rooting powder contains auxins, fungicides and talcum powder.
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