Exam 38: Plant Developmental Responses to External and Internal Signals

Grand Rapids variety of lettuce produces seeds that will not germinate unless they are exposed to light. Phytochrome is also involved in that exposure to red light stimulates germination and far-red light inhibits germination. However, the effect of red light can be reversed by an immediate exposure to far-red light--and vice versa. You design an experiment in which you expose seeds of Grand Rapids lettuce first to red light, then immediately to far-red light, and then immediately to red light again. Would these seeds germinate? Use your knowledge of the phytochrome molecule to explain your reasoning. What if the seeds were exposed first to red light, then immediately to far-red light, then immediately to red light again, and then immediately to far-red light again?

Figure 38-2 The plant in Row B of the accompanying figure demonstrates a photoperiodic response characteristic of:

The site of gravity perception in roots is the root apical meristem .

What happens after the sun goes down?

The photorecepter ____ was first discovered in plants but later found to also be present in fruit flies and mice.

During the day, the leaves of bean plants are ____, and at night they are ____.

The "stress hormone" involved in stomatal closure during water stress is:

____ helps defend plants against viral infection.

You place a coleoptile in unidirectional light and then immediately cover the tip. Which of the following will happen?

Methyl salicylate triggers the genes that code for the systemic acquired resistance pathway .

Which hormone promotes cell division and delays senescence in plants?

Which statement about cryptochrome is false ?

In three sentences or less, explain why a plant placed in a window grows toward the light.

____ is believed to be produced in the leaves and transported to the phloem in the shoot apical meristem.

A circadian rhythm has a period that approximates a(n) 12-hour cycle.

Pr is located in the ____, and after it absorbs red light, the resulting Pfr moves to the ____.

PhyB may inhibit flowering in:

Jasmonic acid is structurally similar to prostaglandins .

Figure 38-1 One conclusion that can be drawn from the accompanying figure is that a low ratio of auxin to cytokinin: