In many species native to tropical wet forests, seeds do not undergo a period of dormancy. Instead, they germinate immediately. Predict the role of ABA in these seeds. How would you test your prediction?

To explore how hormones function, researchers have begun to transform plants with particular genes. In one experiment, a gene involved in cytokinin synthesis was introduced into tobacco plants. Which one of the following results would be expected?a. Individuals produced more lateral branches.b. Stems grew extremely tall and slender.c. Roots were incapable of responding to gravity.d. Stomata were closed most of the time.

"Match each definition with the correct term.Bending of a shoot toward lightGrowth response to touchCycle with a period of about 24 hoursPigment that helps control floweringRelative lengths of night and dayGrowth response to gravityFolding of plant leaves at nighta. phytochromeb. photoperiodc. sleep movementd. circadian rhythme. thigmotropismf. phototropismg. gravitropism"

DRAW IT Indicate the response to each condition by drawing a straight seedling or one with the triple response.

Which of the following types of viruses would you expect to require periods of latency?a. viruses that have large genomes and require a long time for replicationb viruses that require a long time for transmission to new hostsc viruses that require a long time for assembly into complex structuresd. viruses that infect cells of the immune system

Leaflets of Mimosa pudica (common names: sensitive plant, touch-me-not) have a remarkable ability to close up in response to being touched or physically moved. How fast can the leaflets close? How does this occur? And more importantly, what benefit could this unusual response provide to the plant?Researchers studied the rate of closing and reopening of leaflets by measuring changes in the distance between opposing leaflets after being touched. Their results are shown in the accompanying graph (d/dmax is actual leaflet distance relative to maximal leaflet distance). How long does it take for leaflets to close? How long to reopen?

Leaflets of Mimosa pudica (common names: sensitive plant, touch-me-not) have a remarkable ability to close up in response to being touched or physically moved. How fast can the leaflets close? How does this occur? And more importantly, what benefit could this unusual response provide to the plant?Which of the following terms best describes the leaflet movement?a. thigmonastic movementsb. thigmotropismc. thigmomorphogenesisd. apical dominance

Leaflets of Mimosa pudica (common names: sensitive plant, touch-me-not) have a remarkable ability to close up in response to being touched or physically moved. How fast can the leaflets close? How does this occur? And more importantly, what benefit could this unusual response provide to the plant?The mechanism of leaflet closure is similar to what happens during the shrinking of guard cells and closing of stomata (see Figure 37.22). When in the open position, special cells on the upper surface of Mimosa leaflets are filled with water and are under pressure. Explain how osmosis and flow of ions into and out of these special cells may be involved in leaflet closure and reopening.

Leaflets of Mimosa pudica (common names: sensitive plant, touch-me-not) have a remarkable ability to close up in response to being touched or physically moved. How fast can the leaflets close? How does this occur? And more importantly, what benefit could this unusual response provide to the plant?If just the leaflets located toward the end of a leaf are touched, the adjacent leaflets close in fairly rapid succession until all leaflets on a leaf close up. Explain how electrical signaling may be involved in this response.