Download growth hormones promoters inhibitors

GROWTH HORMONES
Plants have natural growth hormones that can either promote or inhibit growth.
PROMOTERS
Auxin is a growth promoter. It causes plant cells to elongate to allow the plant to grow towards a light source. This produces a bend in the stem of the plant.
Gibberellins promote cell enlargement. This allows stems to grow. They also help in the uptake of starch, and reverse dwarfism (delaying the ripening of certain fruits).
Cytokinins promote cell division and differentiation. They stimulate the development of new buds and delay the ageing of leaves.
INHIBITORS
Ethylene is growth inhibitor. It stimulates the aging of plants (ripening and sweetening of fruit, and dropping of leaves from trees). It is the reason why fruits and vegetables spoil in your fridge because the presence of ethylene STIMULATES THE PRODUCTION OF MORE ETHYLENE.
INHIBITORS, CON'D
Abscisic Acid (ABA) is also a growth inhibitor. It blocks the intake of CO2 by controlling the opening and closing of the stomata. It also prevents the growth of new buds, and seed germination.
PLANT TROPISMS
As living organisms, plants have the ability to use energy and obtain materials from the external environment, as well as use energy to convert said materials into useable substances.
That being said, plants can do all of this by responding to external stimuli, much like animals do. A directional growth in response to stimulation from the environment is called a tropism.
The production of plant hormones is affected by the environment, which results in the directional growth. Hormones work to allow plants to respond to these stimuli. Growth toward a stimulus is positive tropism, while growth away from a stimulus is negative tropism.
PHOTOTROPISM
Plants need the energy from the Sun to perform photosynthesis. This causes plants to have an affinity for light. Stems and leaves exhibit positive phototropism, as they will grow towards a light source. The growth is caused by the presence of auxin, which will elongate the cells on the dark side of the stem.
*** Roots exhibit negative phototropism, as they grow away from the light. ***
GRAVITROPISM
Roots exhibit positive gravitropism as they grow down into the ground. Stems and leaves exhibit negative gravitropism as they grow against the force of gravity. THIGMOTROPISM
Thigmotropism is a plant's response to touch. Vines show strong thigmotropism because they tend to grow around objects. Thigmotropism of vines
NASTIC MOVEMENTS
Some plants respond to stimuli independent of the direction of the stimuli. This is known as a nastic movement. Mimosa pudica ­ the sensitive plant
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Carnivorous Plants