Reception and Response in Plants – S6 Biology Notes

These Senior Six Biology notes are part of the coordination topic and explain how plants detect and respond to stimuli. They describe the types of tropism, including phototropism, geotropism, hydrotropism, chemotropism and thigmotropism, and give a simple experiment for several of them. The notes explain how auxin causes plant parts to bend, compare tropic and nastic responses, and use Mimosa pudica as an example of a nastic response. The classic experiments by Darwin, Boysen-Jensen, Paal and Went are summarised. Later sections cover photoperiodism: short-day, long-day and day-neutral plants, how phytochromes control flowering, and what Pr and Pfr do. The notes end with vernalisation.