Plant Hormone
Contents
Key Stage 4 Foundation
Meaning
Plant hormones are chemical messengers (hormones) which affect the growth of a plant.
About Plant Hormones
- Plant hormones may cause cells in the plant to elongate or divide.
- The response of a plant to light and gravity, known as phototropism and gravitropism, is controlled by the plant hormone auxin.
Key Stage 4 Higher
Meaning
Plant hormones are chemical messengers (hormones) which affect the growth of a plant.
About Plant Hormones
- Plant hormones may cause cells in the plant to elongate or divide.
- The response of a plant to light and gravity, known as phototropism and gravitropism, is controlled by the plant hormone auxin.
- The germination of seeds is controlled by a group of plant hormones called gibberellins.
- Gibberellins also stimulate the growth of the plant stem and fruit.
- The ripening of fruit is controlled by ethene.
- Ethene also affects the rate of cell division.
Using Plant Hormones
Auxin
- Gardeners use auxin to encourage cuttings of plants to grow new roots when they are planted.
- Auxin can be used to kill plants by causing them to grow too fast, using up their stores of energy. Since auxin is sprayed on leaves, plants with larger leaves will absorb more and are more likely to die.
Gibberellins
- Farmers use gibberellins to cause seeds to germinate. This can help them all grow at the same time, making it easier to harvest them all at once.
- Gibberellins are also used to make fruit grow faster.
Ethene
- To make fruit last longer they are harvested before they are ripe. When the farmer wants to sell them they put ethene gas in their container causing them to ripen.