Exam 31: Plant Responses to Internal and External Signals

Vines in tropical rain forests must grow toward large trees before being able to grow toward the sun. To reach a large tree, the most useful kind of growth movement for a tropical vine presumably would be the opposite of

Plant hormones can have different effects at different concentrations. This explains how

Figure 31.1 -The heavy line in Figure 31.1 illustrates the relationship between auxin concentration and cell growth in stem tissues. If the same range of concentrations were applied to lateral buds, what curve(s) would probably be produced?

Which of the following would only be activated or upregulated after a plant has already been infected by a pathogen?

After some time, the tip of a plant that has been forced into a horizontal position grows upward. This phenomenon is related to

If the range of a species of plants expands to a higher latitude, which of the following processes is the most likely to be modified by natural selection?

A plant seedling bends toward sunlight because

The aleurone layer is stimulated to release ________ as a result of gibberellin release from the embryo.

Plant hormones produce their effects by

If a farmer wanted more loosely packed clusters of grapes, he would most likely spray the immature bunches with

Charles and Francis Darwin concluded from their experiments on phototropism by grass seedlings that the part of the seedling that detects the direction of light is the

If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering?

In extremely cold regions, woody species may survive freezing temperatures by

A plant will recognize a pathogenic invader

What is the probable role of salicylic acid in the defense responses of plants?

The plant hormone involved in aging and ripening of fruit is

A short-day plant will flower only when

In nature, poinsettias bloom in early March. Research has shown that the flowering process is triggered 3 months before blooming occurs. In order to make poinsettias bloom in December, florists change the length of the light-dark cycle in September. Given this information and clues, which of the following is a correct statement about poinsettias?

If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?

The transduction pathway that activates systemic acquired resistance in plants is initially signaled by