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Leguminous plants of the pea flower family are characterised by nodules on their roots. These contain bacteria that are able to fix nitrogen from the atmosphere into the soil and then plants themselves. The process of crop rotation involves switching between crops that take nitrogen compounds out of the soil and leguminous plants that put them back in.
This clip is from:
Bitesize: Chemistry
First broadcast:
20 March 2008

Classroom Ideas

This clip could be used to introduce the concept of symbiotic relationships. In this case the plants benefit from nitrate production and the bacteria are able to live safely within root nodules. Can students think of any other examples, such as sharks and cleaner fish, and ox and oxpecker birds? Then extend to parasitic relationships. Can students think of any examples, such as mistletoe plants, and tapeworms? Students' understanding is secure if they can explain the difference to their neighbour.

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