Exam 39: Plant Sensory Systems, signals, and Responses

The cells that have phosphorylated phototropin receptors elongate in response to blue light.

Which of the following is the strongest evidence that cytokinins regulate cell divisions?

You discover a chemical that inhibits the conversion of starch to sugar and inhibits the breakdown of chlorophyll and cellulose in fruit.Who might be interested in buying this chemical?

Table 39.1 -Refer to Table 39.1.Plant B is a short-day flower.Why did it fail to flower?

A caterpillar eats a leaf of a plant.The next day it crawls to a nearby leaf to eat.But after eating the second leaf,the caterpillar gets very sick and falls off the plant.Which of the following molecules were involved in the plant's ability to defend itself against the second attack?

Use the following information when answering the corresponding question(s). Researchers found that high doses of nitric oxide were not lethal to soybean cells.Likewise,high doses of reactive oxygen intermediates were not lethal to soybean cells.However,when combined,nitric oxide and reactive oxygen intermediates were very lethal to soybean cells.(M.Delledonne et al.2001.Signal interactions between nitric oxide and reactive oxygen intermediates in the plant hypersensitive response.Proceedings of the National Academy of Sciences,USA 98(23):13454-59. ) -Refer to the paragraph on Delledonne et al.Based on the findings presented in the paragraph,combined with what you have learned about the hypersensitive response,which sequence of events occurs when a pathogen infects a plant cell? (Only some of the events will be used. ) 1)The R protein binds to the avr protein. 2)The pathogen releases avr proteins. 3)The plant cell produces nitric oxide. 4)The pathogen produces reactive oxygen intermediates. 5)A signal transduction cascade occurs. 6)The plant cell and the pathogen die. 7)The pathogen dies,the plant cell lives. 8)The plant cell produces both nitric oxide and reactive oxygen intermediates.

Which of the following is not a characteristic of plant hormones?

Suppose a plant had a nonsense mutation in a gene that encodes for an enzyme required for the synthesis of gibberellic acid.If the plant is homozygous at this locus,what will its phenotype be?

Which of the following signals indicates shade to a plant?

Figure 39.2 -Suppose you laid a seedling on its side so that the root was parallel to the ground.Immediately after the change in position,where in the root cells (position A,B,or C in Figure 39.2)would you find the amyloplasts? The answer should be one of the positions shown in Figure 39.2.

Which of the following cannot be sensed by plants?

The addition of a phosphate group to a protein is called _____,and it usually results in _____.

Why does auxin move through the plant slower than sucrose does?

You buy some fresh fruit at the grocery store.When you get home you are in a hurry,and you put the fresh fruit in the crisper with some overripe fruit.At the end of the week you are disappointed to find that your new fruit has already become overripe.What happened?

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 compounds from the caterpillar alone do not attract parasitoid wasps?

A particular species of virus carries a gene for salicylate hydroxylase,an enzyme that breaks down salicylic acid.Will this virus be more or less virulent to plants than other viruses?

Figure 39.2 -Suppose you laid a seedling on its side so that the root was parallel to the ground.Several hours after the change in position,where in the root cells (position A,B,or C in Figure 39.2)would you find the amyloplasts?

A certain bacterium infects a plant's upper leaves.A few days later,bacteria of the same species attempt to infect the same plant's roots but are unsuccessful.What process is responsible for the plant's ability to prevent this infection?

Shoots that grow vertically toward the Sun can be characterized as _____.

In the fall,the leaves of some trees change color.This happens because chlorophyll breaks down and the accessory pigments become visible.What hormone is responsible for this?