Interpret red/far-red treatments through Pr/Pfr conversion, explain auxin elongation via cell-wall and water-potential changes, and link gibberellin trends to transcription and germination.
Animals and plants can detect and respond to light.
The drawing shows the results of some experiments investigating phototropisms. The diagram shows a coleoptile of a seedling.
intact coleoptile illuminated from one side
tip of coleoptile removed and remaining coleoptile illuminated from one side
black cap placed on tip of coleoptile and coleoptile illuminated from one side
Experiment 3:
coleoptile illuminated and the tip removed
tip replaced on one side of the remaining coleoptile that is then kept in the dark
Scientists concluded that these results suggest a plant growth substance is involved in regulating the phototropic response.
Discuss how the results of these experiments support the role of a plant growth substance in the phototropic response of plants.
Use the information for these experiments and your own knowledge to support your answer.