B5 Page 6 Flashcards
Example of a plant part which is positively phototropic?
Shoots, they grow towards light.
What is phototropism?
The growth of some parts of a plant towards or away from light.
Example of a plant part which is negatively phototropic?
Roots, grow away from light.
What does phototropism helps the plant do?
Helps the plant survive.
Describe positive phototropism.
Plants need sunlight to photosynthesise. Photosynthesis occurs mainly in the leaves so its important for plant shoots which will grow leaves grow towards light.
Describe negative phototropism.
Plants need nutrients from the souls to grow. Phototropism means the roots will grow way from light down into the soil where they can absorb water and nutrients.
What are auxins?
Auxins are chemicals that control growth near the tips of shoots and roots.
Where are auxins produced?
In the tips and diffuse backwards to stimulate cell elongation. This occurs in the cells just behind the tips.
What happens If the tip of a shoot is removed?
No auxins are available and the shoot may stop growing.
What are auxins involved in the responses of plants?
Light, water and gravity.
How does the growth make it “bend” towards the light?
The auxins accumulate on the shade side of the shoot therefore making the area in the shade elongate therefore “bending” towards the light.
