Plant Hormones Flashcards

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1
Q

Auxins

A

Control cell elongation
prevent leaf fall
maintain apical dominance
Stimulate release of ethene

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2
Q

Gibberelins

A

Stem elongation
Trigger seed germination
Stimulate pollen tube growth in fertilisation

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3
Q

Ethene

A

Fruit ripening
Abscission

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4
Q

ABA abscisic acid

A

Dormancy of seeds and buds
Antifreeze production
Stomata closing

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5
Q

Seed germination

A

Seed absorbs water embryo activat produce gibberelins - stimulate enzymes to break down food stores
Produce atp to grow

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6
Q

Apical dominance

A

High conc of auxin supresss lateral shoots
Growth at tip in main shoot
Inhibits lateral shoots
Low conc of auxin promotes root growth

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7
Q

Auxin func

A

Synthesised in meristem
Diffuse from tip
Low pH develops
Vacuoles bigger and cell wall stretches
Cell wall becomes rigid auxin is destroyed no cell elongation

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8
Q

Gibberelin func

A

Elongation of plant stems between internodes

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9
Q

Removal of gibberelins

A

Dwarf plants
Stems shorter reduce waste and vulnerability to damage by weather

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10
Q

Synergism

A

Hormones working together eg auxins and gibberelins

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11
Q

Antagonism

A

Hormones having opposite effects
Eg gibberellins and abscisic acid

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12
Q

Abscission

A

Lengthening of dark periods cause abscission - dormancy
Falling conc of auxins trigger ethene production - switch on genes in cell to stimulate enzyme production digest separation layer
Vasc bundles sealed off and fatty deposits form protective layer

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13
Q

Stomata control

A

ABA release under abiotic stress when water falls
Changes in ionic conc of guard cells incr turgor of cells closing stomata

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14
Q

Chemical defences

A

Tannins- phenols bitter taste and toxic to insects
Alkaloids - affect metabolism and poison animals eg caffeine toxic to fungi
Terpenoids- toxins that interfere w animals eg pyrethrin interferes w nervous sys of insect

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15
Q

Pheromones

A

Chemical which effects behav of other members of species
Pheromone which absorbed by other leaves trigger production of callose
Communicate w neighbour via roots
Signals larger predators VOC - cabbage and wasps, apples and mites

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16
Q

Response to touch

A

Leaves touched fold down and collapse frightens off or dislodges animals

17
Q

Phototropism

A

Grow towards the light
Auxinl down shaded part causes bending causes elongation

18
Q

Geotrophism

A

+ve towards gravity eg roots
-ve against gravity eg leaves

19
Q

Commercial use of hormones

A

Ethen - control of ripening and fruit dropping
Micropropagation- add auxin
Gibberelins- removal dwarf plants delay ripening
Auxin produce seedless fruits