Exam 39: Plant Sensory Systems, signals, and Responses

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! Based on what you know about plant sensation,which of the following hypotheses is the most reasonable to explain this phenomenon?

Use the following information when answering the corresponding question(s). Some plants have continually produced secondary defense compounds.Other plants are induced to form secondary defense compounds when they are injured.Corn seedling leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate volatile chemicals (LOX products),and after 6 hours large amounts of terpenoid compounds are released into the air.The terpenoids are released not only from the leaf being chewed,but from all leaves of the plant.The terpenoid compounds attract a parasitoid wasp female that lays her eggs on the caterpillar.When the wasp larvae hatch,they eat and kill the moth caterpillar.(T.C.J.Turlings,J.H.Loughrin,P.J.McCall,U.S.R.Rose,W.J.Lewis,and J.H.Tumlinson.1995.How caterpillar-damaged plants protect themselves by attracting parasitic wasps.Proceedings of the National Academy of Sciences 92:4169-74. ) -Refer to the paragraph on how caterpillar-damaged plants protect themselves by attracting parasitic wasps.How could you test the hypothesis that caterpillar saliva and a wound are both necessary to attract the parasitoid wasps?

Use the following information when answering the corresponding question(s). Some plants have continually produced secondary defense compounds.Other plants are induced to form secondary defense compounds when they are injured.Corn seedling leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate volatile chemicals (LOX products),and after 6 hours large amounts of terpenoid compounds are released into the air.The terpenoids are released not only from the leaf being chewed,but from all leaves of the plant.The terpenoid compounds attract a parasitoid wasp female that lays her eggs on the caterpillar.When the wasp larvae hatch,they eat and kill the moth caterpillar.(T.C.J.Turlings,J.H.Loughrin,P.J.McCall,U.S.R.Rose,W.J.Lewis,and J.H.Tumlinson.1995.How caterpillar-damaged plants protect themselves by attracting parasitic wasps.Proceedings of the National Academy of Sciences 92:4169-74. ) -Refer to the paragraph on how caterpillar-damaged plants protect themselves by attracting parasitic wasps.What can you conclude based only on the information in the preceding paragraph?

A particular parasitoid is heterozygous for a gene that binds plant pheromones.Which of the following is true of that parasitoid?

Use the following information when answering the corresponding question(s). The shade avoidance response is a plant's way of changing its growth pattern when it is being shaded by another plant.Upon exposure to shade,many plants will grow taller,flatten their leaf angle,and extend their leaves further from their stems in order to reach full sunlight.Research performed by Pierik et al.(Interactions between ethylene and gibberellins in phytochrome-mediated shade avoidance responses in tobacco.2004.Plant Physiology 136:2928-36;online at http://www.plantphysiol.org/cgi/content/full/136/2/2928)examined the role of ethylene and gibberellins on the shade avoidance response in tobacco plants.The shade avoidance response is known to involve phytochromes. -Refer to the paragraph on the research done by Pierik et al.When the researchers inhibited the synthesis of gibberellins in the tobacco plants,neither ethylene nor far-red light could trigger a shade avoidance response.Taken together with the data presented above,these data suggest that gibberellins _____.

Antisense gene sequences can be used to block the transcription of specific genes in a cell or group of cells.Suppose you took a cutting from a plant and treated it with an antisense gene that would block the transcription of an enzyme involved in auxin production.What would happen to your cutting?