A plant mutant that shows normal gravitropic bending but does not store starch in its plastids would require a reevaluation of the role of in gravitropism.a. auxinb. calciumc. statolithsd. differential growth

What evidence suggests that ABA from roots can signal guard cells to close?a. If roots are given sufficient water, guard cells close anyway.b. If roots are dry, guard cells begin to close—even though leaves may not be experiencing water stress.c. Applying ABA on guard cells directly causes them to close.d. If roots are dry, the ABA concentration in leaf cells drops dramatically.

Plant hormones act by affecting the activities ofa. genes.b. membranes.c. enzymes.d. genes, membranes, and enzymes.

Why was it logical to predict that amyloplasts function as statoliths?a. They are dense and settle to the bottom of gravity-sensing cells.b. They are present only in gravity-sensing cells.c. They make a direct physical connection with membrane proteins that have been shown to be gravity-receptor molecules.d. Their density changes in response to gravity.

Buds and sprouts often form on tree stumps. Which hormone would stimulate their formation?a. auxinb. cytokininc. abscisic acidd. ethylene

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