Flashcards in The Plant Nervous System (T2) Deck (10):
Give an example of a plant that responds quickly to stimuli and advise how it does this..
The Venus fly trap. The quick movement is brought about by changes in the tugor of specialised cells found at the base of the leaves.
What is tropism? Give an example.
Tropism is when a plant grows to a directional stimulus.
A plant grows in a pot with the top of the plant getting the most sunlight. If you turn the pot on its side, eventually you will see the plant growing upwards towards the light.
Two stimuli are working on the plant: light and gravity.
Give two examples of directional stimuli (stimuli acting in a specific direction)
What is positive tropism?
When a plant grows towards the direction is the stimulus.
What is negative tropism?
When a plant grows away from the direction of the stimulus.
What is phototropism?
A growth response to light.
What is geotropism?
A growth response to gravity.
Why, in most species of plant, is positive phototropism the strongest response of the shoot?
Because the shoot needs light to undertake photosynthesis.
If a shoot grows towards the light it will ensure that the leaves are at an angle to the stem and can receive the maximum amount of sunlight.
Why are plant roots generally strongly geotropic?
To ensure that the roots grow down into the soil where they can reach soil and mineral ions and secure an anchorage.