Chapter 20 Study Questions

Define the terms “floral evocation” and “phase change.” How is phase change regulated by microRNAs?

Textbook Reference: Floral Evocation: Integrating Environmental Cues, p. 592; The Shoot Apex and Phase Changes, pp. 592–594
Define the following terms in relation to circadian rhythm: period; phase; amplitude; entrainment; zeitgeber; free-running; temperature compensation; subjective day; subjective night.

Textbook Reference: Circadian Rhythms: The Clock Within, pp. 594–596
What is the ecological function of photoperiodism? Discuss variations in the photoperiodic response.

Textbook Reference: Photoperiodism: Monitoring Day Length, pp. 597–599
Define the “clock hypothesis” of photoperiodism and describe the evidence that supports it. What is the relationship between the clock hypothesis and the coincidence model of oscillating light sensitivity?

Textbook Reference: Photoperiodism: Monitoring Day Length, pp. 599–603
What is the evidence that phytochrome is the primary photoreceptor in photoperiodism?

Textbook Reference: Photoperiodism: Monitoring Day Length, pp. 603–604
Define “vernalization” and discuss the role of epigenetic changes in gene expression. Textbook Reference: Vernalization: Promoting Flowering with Cold, pp. 605–608
Discuss how grafting studies led to the hypothesis of a phloem-transmissible floral stimulus called “florigen.”

Textbook Reference: Long-distance Signaling Involved in Flowering, pp. 608–610
Discuss the mechanism of action of florigen in stimulating flowering in Arabidopsis. What other factors influence flowering?

Textbook Reference: The Identification of Florigen, pp 610–612
What are the major categories of genes that regulate floral development and how do they interact to regulate floral organ formation?

Textbook Reference: Floral Meristems and Organ Development, pp. 613–618
Describe the “quartet model” of floral organ specification.

Textbook Reference: Floral Meristems and Organ Development, pp. 618–619