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37 NCEA Style Question: Biological Clocks in Plants
1. Carnations require at least two or three weeks with days longer than 14 hours to initiate flowering. Flowering is controlled by the pigment phytochrome in response to the photoperiod.
(a) Describe this pattern of flowering:
(b) Explain how phytochrome controls flowering in carnations:
2. Tulips have large flowers with petals that open during the day and close at night. Discuss how this regular movement of the petals enhances the plant’s reproductive success. You may use more paper if required.
3. Some plants respond to seasonal changes by alternating periods of growth and dormancy. Describe the environmental cues that are important in these life cycle responses and discuss their adaptive value:
