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The effects of IAA on root growth

Produced by Science & Plants for Schools (SAPS), this activity enables students to investigate the effects of the plant hormone indole acetic acid (IAA) on root growth in mustard seedlings.

Different concentrations of IAA appear to have differing effects on root growth. These effects may vary from one species to another but generally at low concentrations IAA stimulates root growth while at higher concentrations it inhibits root growth.

Mustard seedlings are relatively sturdy and have large root hairs at the top of the root. These make it easy to see where the root begins and thus students can measure the root length accurately.

The investigation is designed for students following a Scottish Highers course but it is equally useful for other post-16 courses in biology.

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