Q16 - Cytokinin Receptor Loss and Day-Length Stress in Arabidopsis
Cytokinin is a plant hormone involved in stress signalling, which may affect responses to day-night cycles. Arabidopsis plants were grown under 8 hours light / 16 hours dark for 12 days, then four different light / dark regimes for one cycle. Patches of cell death were measured in leaves after this.
Using the information and data, determine which of the statements are true or which are false.
A. Increased light exposure is the major cause of cell death in cytokinin receptor knockouts in this experiment.
B. A condition of 12 h light and 12 h dark will lead to a high percentage of cells dying in cytokinin receptor knockout plants.
C. Cytokinin increases leaf stress.
D. Cytokinin helps adjust expression of circadian clock related genes.
Question reproduced from IBO 2017, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions