CH 39

Plant hormones act by directly affecting the activities of _____. a. membranes b. genes and enzymes c. enzymes d. signal transduction pathways e. genes

Which of the following seedlings will probably bend toward light? a. one whose tip is separated from its base by a gelatin block b. one whose tip is cut off c. one whose tip is covered with a black plastic cap d. one whose tip is cut off and topped by a gelatin block containing no plant substances e. one whose tip is separated from its base by aluminum foi

What is the physical basis of the phototropic response? a. Cell elongation. b. Photosynthesis. c. Cell transport. d. Cell shortening.

Where does the majority of stem growth in a plant occur? a. Apical meristem. b. Lateral branches. c. Both the apical meristem and lateral branches. d. Axillary buds.

Which term describes the direction of auxin transport in a plant? a. Bidirectional. b. Multidirectional. c. Circular. d. Polar.

Which of these plant hormones is not typically considered a growth-promoting substance? a. brassinosteroids b. auxin c. cytokinin d. abscisic acid e. gibberellin

Thigmotropism is a movement in response to _____. a. chemicals b. light c. touch d. temperature e. gravity