AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to describe the effects of some plant hormones and…
Full specification wording
Use of plant hormones (HT only): Students should be able to describe the effects of some plant hormones and the different ways people use them to control plant growth.
Auxins promote cell elongation and are used as selective weed killers (disrupting growth in broad-leaved weeds but not narrow-leaved crops), in rooting powders to stimulate root growth in…
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 4
Study notes
From the checked teaching notes for this specification point.
The idea
Auxins promote cell elongation and are used as selective weed killers (disrupting growth in broad-leaved weeds but not narrow-leaved crops), in rooting powders to stimulate root growth in cuttings, and in tissue culture to promote growth. Ethene is a gas that controls cell division and the ripening of fruits; it is widely used in the food industry to control ripening during storage and transport. Gibberellins initiate seed germination and are used commercially to end seed dormancy, promote flowering throughout the year, and increase the size of fruits, such as seedless grapes.
What earns the marks
- Auxins are used as selective weed killers, targeting broad-leaved weeds without harming narrow-leaved crops.
- Auxins are used in rooting powders to stimulate root formation in plant cuttings, and in tissue culture to promote growth.
- Ethene is used in the food industry to control the ripening of fruit during storage and transport.
- Gibberellins are used to end seed dormancy, encouraging seeds to germinate at all times of the year.
- Gibberellins are also used to promote flowering and to increase the size of fruits.
Common mistakes and how to put them right
Confusing the roles of different hormones.
Put it right: Remember auxins are for roots and weeds, ethene is for ripening, and gibberellins are for seeds, flowers, and fruit size.
Stating that weed killers kill all plants.
Put it right: Selective weed killers specifically target broad-leaved plants and leave narrow-leaved crops unaffected.
Forgetting that ethene is a gas.
Put it right: Explicitly state that ethene is a gaseous hormone used to control fruit ripening.
Exam tips
- Memorise at least one specific commercial use for each of the three hormones: auxins, ethene, and gibberellins.
- When discussing ethene, mention its use in transport, allowing fruit to be picked unripe and ripened just before sale.
Try the lesson
The start of the Use of plant hormones (HT only): Students should be able to describe the effects of some plant hormones and the different ways people use them to control plant growth. lesson, made from checked teaching notes for this specification point.
Have a go first
A gardener wants to make cuttings of a shrub produce roots quickly so that new plants can be grown. Which plant hormone would be applied to the base of the cuttings, and what is its effect?
Listen
Auxins promote cell elongation and are used as selective weed killers (disrupting growth in broad-leaved weeds but not narrow-leaved crops), in rooting powders to stimulate root growth in cuttings, and in tissue culture to promote growth. Ethene is a gas that controls cell division and the ripening of fruits; it is widely used in the food industry to control ripening during storage and transport. Gibberellins initiate seed germination and are used commercially to end seed dormancy, promote flowering throughout the year, and increase the size of fruits, such as seedless grapes. A strong answer earns marks for these points. Auxins are used as selective weed killers, targeting broad-leaved weeds without harming narrow-leaved crops. Auxins are used in rooting powders to stimulate root formation in plant cuttings, and in tissue culture to promote growth. Ethene is used in the food industry to control the ripening of fruit during storage and transport. Gibberellins are used to end seed dormancy, encouraging seeds to germinate at all times of the year. A common slip: Confusing the roles of different hormones. Instead, remember auxins are for roots and weeds, ethene is for ripening, and gibberellins are for seeds, flowers, and fruit size. Exam tip: Memorise at least one specific commercial use for each of the three hormones: auxins, ethene, and gibberellins.
See it
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Use of plant hormones (HT only): Students should be able to describe the effects of some plant hormones and the different ways people use them to control plant growth.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge