Plants use direct environmental stimuli for orientation in growth and movement. This is called tropism. The responses of the plant may be toward (positive) or away (negative) from the external stimulus or stimuli.Click the links below to learn more about the different types of stimuli and the plants reaction to it:Phototropism-Reaction to light and different wavelengths.his is called tropism. The responses of the plant may be toward (positive) or away (negative) from the external stimulus or stimuli. Click the links below to learn more about the different types of stimuli and the plants reaction to it:
I'm thinking about training for a marathon. A marathon is 26.2 miles or 42 kilometers. Although some marathons differ in their terrain (some are very flat, some are extremely hilly) and degree of difficulty, the distance is always 26.2 miles.
Comments. An ultra-marathon is any race longer than the classic marathon distance of 26.2 miles. Growing ever more popular, you can do an event almost every weekend in Britain at the moment (although that's not recommended if you don't like bits of you falling off).