Once sameer observed a plant kept in his room was bending and growing towards the windows direction only. He asked his teacher the reason behind the bending of the plant towards the window. Name the phenomenon observed and how does this phenomenon take place? What are the values shown by Sameer?
Answers
Phenomenon-Phototropism
How it takes place?---There are several signaling molecules that help the plant determine where the light source is coming from which helps the plant, and this activates several genes, which change the hormone gradients allowing the plant to grow towards the light. The very tip of the plant known as the coleoptile is necessary in light sensing.Phototropism in plants such as Arabidopsis thaliana is directed by blue light receptors called phototropins. Other photosensitive receptors in plants include phytochromes that sense red light and cryptochromes that sense blue light. Different organs of the plant may exhibit different phototropic reactions to different wavelengths of light. Stem tips exhibit positive phototropic reactions to blue light, while root tips exhibit negative phototropic reactions to blue light. Both root tips and most stem tips exhibit positive phototropism to red light.[citation needed] Cryptochromes are photoreceptors that absorb blue/ UV-A light, and they help control the circadian rhythm in plants and timing of flowering. Phytochromes are photoreceptors that sense red/far-red light, but they also absorb blue light. The combination of responses from phytochromes and cryptochromes allow the plant to respond to various kinds of light.[14] Together phytochromes and cryptochromes inhibit gravitropism in hypocotyls and contribute to phototropism.
Values---Observative,Curious