Plant Responses Flashcards
What is tropsim?
a growth response controlled by direction stimulus
What are the main types of tropism?
- Gravitropism
- Chemotropism
- Phototropism
- Thigmostopism
- Hydrotropism
What is Gravitropism?
When the direction of root growth is determined by the direction of the gravitational pull
What is Chemotropism?
When the direction of growth is determined by particular substances
What is Phototropism?
When direction of growth is determined by direction of light
positively means towards, negatively means away
What is Thigmostopism?
When direction of growth is determined by touch
What is Hydrotropism?
When direction of growth is determined by water
What coordinate and control a plants responses?
Hormones
What are the main types of plant hormones?
- Auxin
- Cytokinins
- Gibberellins
- Abscisic acid
- Ethene
What is Auxin?
a class of plant hormones that control cell elongation
What are Cytokinins?
a class of plant hormones that promote cell division, or cytokinesis
What are Gibberellins?
a class of plant hormones that ripen plants (for fruits and flowering)
What are Abscisic Acids?
a class of plant hormones that regulates plant growth (seed maturation and dormancy)
What are Ethenes?
a class of plant hormones that speeds up ripening and controls cell division during plant growth
What are the two types of responses that plant hormones can bring about?
- synery, which amplifies
- antagonistic, which cancels out
Describe the process of phototropism.
- Illumination occurs on one side of the plant
- Auxin moves (either by xylem or phloem) to the unexposed area of the plant
- This causes growth (cell elongation) on that side
- As a result, the plant pends towards the light
Explain the effect that Indole Acetic Acid (IAA) has on phototropism.
- Uneven distribution of IAA = uneven growth
- higher concentrations of IAA results in a greater rate of cell elongation
- higher concentration of IAA on the shaded side of the shoot, the faster the rate of cell elongation, which causes the shoot to bend towards the light
Describe the process of graphitropism.
