Plant Responses To The Environment Flashcards
What 3 stimuli do plants respond to?
- Biotic factors
- Abiotic factors
- External stimuli (e.g. grazing)
What response might a plant have to higher temperatures?
Deposit thicker layers of wax on their leaves
What response might a plant have to windy conditions?
Heavily lignified vascular tissues
Suggest how the release of tannins are a response.
Tannins are toxic to microorganisms and larger herbivores. In the leaves, tannins are found in the upper epidermis, and make the leaves taste bad. In the roots they prevent infiltration by pathogenic organisms.
Suggest how alkaloids are a response to herbivores.
Alkaloids are derived from amino acids, and act as a feeding deterrent, as they taste bitter. They are located in the growing tip and flowers and peripheral cell layers
What are pheromones?
Chemicals which are released by one individual and which can affect the behaviour or physiology of another.
What are tropisms?
Directional growth responses of plants.
What is (positive) phototropism?
Growth towards the light.
What is (positive) geotropism?
Growth towards the pull of gravity.
What is (positive) chemotropism?
Growth towards chemicals (e.g. pollen tubes growing down the style).
What is thigmotropism?
Response to touch (i.e. to grow around other plants/structures).
What is a nastic response?
A non-directional stimulus.
How do plant hormones differ from animal hormones?
They are not produced in endocrine glands but in cells in a variety of tissues.
What are the effects of cytokinins?
- Promotes cell division
- Delay leaf senescence
- Overcome apical dominance
- Promote cell expansion
What are the effects of abscisic acid?
- Inhibits seed germination and growth
- Causes stomatal closure when water availability is low
