Exam 37: Plant Sensory Systems, Signals, and Responses

Plant growth regulators ________.

Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only ¼ inch of soil is that the ________.

You have a small tree in your yard that is the height that you want it, but it does not have as many branches as you want. How can you prune it to trigger it to increase the number of branches?

The heavy line in the accompanying figure 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 can function in signal transduction in plants? I. calcium ions II. nonrandom mutations III. receptor proteins IV. red light V. second messengers

Plants often use changes in day length (photoperiod) to trigger events such as dormancy and flowering. It is logical that plants have evolved this mechanism because photoperiod changes ________.

To find the gene that encodes for the blue-light receptor, researchers inserted the gene for the PHOT1 protein into insect cells growing in culture. When they exposed the transgenic cells to blue light, they found that the PHOT1 protein became phosphorylated. No other plant proteins were present in the insect cells. Which of the following is a reasonable conclusion from this result? The PHOT1 protein ________.

The dropping of leaves and fruit are principally controlled by ________.

You have discovered a previously unidentified plant, and you cultivate it in your lab. You notice that its flowers close when people are talking yet are open when the lab is relatively quiet. You suspect that this plant may have the ability to hear! Which of the following hypotheses is (are) the most reasonable to explain this phenomenon? I. There is a cell-surface protein on the epidermal cells that becomes phosphorylated in response to vibration by sound waves. II. There are tiny hairs on epidermal cells that bend in response to the vibration of sound waves, triggering an action potential in epidermal cells. III. There is a cell-surface receptor on root cells that becomes phosphorylated when the soil vibrates in response to sound waves.

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

According to the acid-growth hypothesis, auxin works by ________.

Before plowing a field, a farmer thought the bare field looked weed-free. Three days after plowing and turning over the soil, he was amazed to see thousands of tiny seedlings. What is the most likely reason for the mass germination of seeds?

A researcher found a beautiful plant while traveling in Alaska and collected its seeds. When she came back to Florida, she soaked some seeds in pure water and some in water with a hormone. When she put the seeds in soil to grow, only the seeds that had been soaked with the hormone germinated. The hormone most likely was ________.

Which of the following best explains both the growth of a vine up the trunk of a tree as well as the directional growth of a houseplant toward a window?

Which of the following is the most likely plant response to an attack by herbivores?

For a plant to initiate chemical responses to herbivory before it is directly attacked by herbivores, ________.

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

A botanist discovers a plant that lacks the ability to form starch grains in root cells, yet the roots still grow downward. This evidence would refute the long-standing hypothesis that ________.

The apical bud of a shoot produces ________, resulting in the inhibition of lateral bud growth.

You are part of a desert plant research team trying to discover crops that will be productive in arid climates. You discover a plant that, under water-deficit conditions, produces a hormone that triggers a suite of drought responses. Most likely the hormone is ________.