Plants & hormones
Even if you plant seeds upside down, the shoot will grow up & the root will grow down
Hormones used to grow plants:
- Cuttings can be dipped in rooting powder ( plant hormone) to encourage growth
Hormones used as weed killer:
- Hormones make the plants use up all of their energy to grow fast
- The plants aren't strong enough to stand, so fall & die
Where the plant stem bends TOWARDS the light
Auxin is a plant homone that controls cell growth.
The auxin is usually spread out in the stem.
When light hits the auxin, it is destroyed, meaning that there is no auxin on that side of the shoot.
The side with more auxin elongates more than the side with no auxin
The plant bends towards the light
Geotropism / Gravitropism
The plant is growing HORIZONTALLY, so the auxin makes the root grow down & the shoot grow up
- Auxin in the shoot make the cells elongate
- Auxin in the root makes the cells shorten
Gravity makes the auxin fall to the bottom of the plant
The auxin elongates the side of the shoot so it grows up
The auxin shortened the side of the root so it grow down