Hormones Case

Plant Hormones

Auxin Growth, prevents leaves from falling, promotes flowering and fruiting

Gibberellines General Growth

Cytokinins Cell Division, regulate cell cycle

Abscisic Acid Stomata closing, Initial growth, seed dormancy

Ehtylene Senescence, aging, and dying

Brassinosteriods Cell elongation

Systemin Defense Responses

Auxin

In high concentration, auxin inhibits growth in dicots so it is used in herbicide.

Auxin and Phototropism

* The top of the shoot tip senses the sunlight and tells the opposite side to grow so the plant can bend.

* In STEM PHOTOTROPISM, auxin promotes cell elongation.

Auxin and Gravitropic

* The root cap senses the gravity which then helps distribute auxin evenly and the plant grows up. Auxin is redistributed by gravity.

* In ROOT GRAVITROPISM, auxin inhibits growth.

Auxin Promotes Apical Dominance

* Apical dominance is when auxin suppresses lateral growth and instead tells the plant to gow tall. If you cut off the auxin then the plant starts branching

Cytokinins

* Proportions of auxin and cytokinin control root and shoot development. Auxin promotes ROOT growth. Auxin promotes SHOOT growth. If they're both even then the plant does not grow correctly.

* A bacteria called Agrobacterium tumefaciens infects trees. The bacteria make cytokinin releases so the tree keeps growing into a cancer while the bacteria benefit from it and take opines that are created.

Gibberellins

* Stimulates plants to grow abnormally all. Plants need it for height

ABA

* Single compound. Tells the rest of the plant to close its stomata is one is dry.

* Gibberellins and ABA work against each other. Giberllins promote growth while ABA inhibits growth.

Brassinosteriods

* Similar to steroids and promote growth in stems

Ethylene

* Single compound

* Fruit ripening, flower drop, leaf drop

* Auxin and ethylene control lead drop. Ethylene tells leaves to drop off and auxin tells the new babe leave to stay on. The abscission zone is a layer formed to seal the stem where the leaf was attached.

Systemin

* When a plant is being attacked, the undamaged cells produce Jasmonic acid which triggers Proteinase inhibiters(bad taste) and pheromones. The pheromones call

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