Firstly, if you don't know what a stimulus is, it may be an idea to have a read of post 2.79 and then come back to here.
Plants respond to many stimuli, here are quite a few, it may be an idea to pick like 3 to remember for the exam as there is no need to learn all of them...
- Climbing plants have a sense of touch, so they can find things to climb and reach sunlight
- Plants can sense gravity, so their roots and shoots grow in the right direction (if they didn't sense gravity it would be chaos, some roots would grow up and some shoots would grow down etc)
- Plants sense the direction of light and grow towards it to maximise light absorption for photosynthesis
Specific examples...
- If cattle overgraze (eat LOADS of the field) they start to eat lots of white clover (as there is no grass left), the white clover will respond by producing toxins to avoid being eaten
- At low temperatures carrots produce antifreeze proteins which bind to ice crystals and lower the temperature that water freezes at, stopping more ice crystals from growing (ngl, this ones pretty cool)
Example credit: CGP
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