Plant Hormones
Biology: AQA GCSE Higher, topic 5.4.1
Plant Hormones
Plants produce hormones that allow them to respond to changes in the external environment. The key plant hormones are:
Auxins
- Auxins change growth patterns to allow roots and shoots to move either towards or away from a stimulus (change in conditions).
- Responses to stimuli that involve directional growth are called tropisms.
Gibberellins
- Gibberellins are important in starting off the seed germination (sprouting) process.
Ethene
- Ethene is a gas that controls cell division and the ripening of fruits.
Test yourself on Plant Hormones
Which of the three main plant hormones is a gas?
A packet of dry seeds fails to sprout even when watered and kept warm. Which plant hormone is most likely to be missing?
Bananas left in a bowl turn from green to yellow and become soft after a few days. Which hormone causes this change?
A pot plant on a windowsill grows at an angle, leaning towards the window instead of growing straight upwards. Which hormone caused this change in growth direction?
A supermarket stores unripe green tomatoes in a sealed room filled with a particular gas to make them turn red and soften before they reach the shelves. Which hormone is being used?