Plant hormones

• Roots need to grow downwards to absorb water and minerals from the soil - positive gravitropism
• Shoots grow towards light for photosynthesis - positive phototropism
• Auxins are produced at shoot tips, they diffuse through cells and cause elongation of cells on one side
• Auxin gathers on the shaded area of the shoot
• Ethene ripens fruit in supermarkets
• auxins are used in selective weedkillers , rooting powders and promote growth is tissue cultures ( growing plant cells in labs )
• Gibberellins increase seed germination ( ends seed dormancy), promotes flowering and increases fruit size