Use of plant hormones – Higher - Plant hormones - AQA - GCSE Biology (Single Science) Revision - AQA

Use of plant hormones – Higher

There are many , and there are a number of different groups. They are used in and to have a specific effect.

were the first class of plant hormones to be discovered. Their main function is to help plants grow and auxin stimulates plant cells to . The tips of the growing stems and roots (apical meristem) of a plant is one of the main places where auxin is produced. The apical meristem is also the location that all other parts of a plant grow from - the stem, leaves and flowers.

Auxins are one specific group of hormones that are used:

as weed killers
as rooting powders
for promoting growth in tissue culture

Weedkillers

Selective weedkillers kill some plants, but not others. This can be useful for getting rid of dandelions in a lawn without killing the grass or weeds that compete with crops such as wheat. The selective weedkiller contains a growth hormone that causes the weeds to grow too quickly and die. Because most weeds have broader leaves than grass or wheat, the weedkiller is absorbed in larger quantities by the weeds.

Selective weedkillers kill plants that some species of animals rely on as a food source. This can result in a reduction of biodiversity.

Rooting powder

Plant cuttings can be dipped in hormone rooting powder before planting.

Synthetic plant hormones are used to control plant growth. For example, rooting powder contains growth hormones that make stem cuttings develop roots quickly.

Promoting growth in tissue culture

Scientists with tissure cultured plants — Image caption,
Scientists with cultured plants

Tissue culture is a technique used to grow whole new plants from small sections of a parent plant.

Hormones are used to stimulate cell division and elongation.

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