Plant hormones Flashcards
What do plant hormones do?
control and coordinate plant growth and development
What is a tropism?
a plant’s response to a stimulus by growing
What is a postive/negative tropism?
a positive tropism is when a plant grows towards the stimulus
a negative tropism is when it grows away
What is growing towards light called?
positive phototropism
What is growing downwards/towards the pull of gravity called?
positive gravitropism/geotropism
What are auxins?
plant hormones that make a cell grow longer
What are auxins affected by and what do they cause?
light
positive phototropism in shoots
negavitve phototropism in roots
Where is auxin produced?
in cells near the top of a shoot
Describe how auxin causes plants to grow towards the light.
- produced in the tip of the shoot
- moves away from light to the shaded side of plant
- causes cell elongation in shaded side
- plant grows towards light
What does auxin cause in shoots and roots?
cell elongation in shoots
inhibits cell elongation in root cells
Why do plants grow towards the light?
plants grow towards the light so that they can absorb maximum light for photosynthesis
What happens when the light source is directly above the plant?
- auxin is produced in the tip
- it diffuses downwards evenly
- the cells elongate evenly
- it grows straight upwards
What is gibberellin and what does it do?
- helps seeds to germinate
- makes seedless/bigger fruit
- makes flowers bloom
What is ethene gas and what does it do?
-helps fruit ripen
Name 2 uses of auxin
- selective weed killers
- rooting powders
