Chapter 30

Plant hormones ___________. a. often have multiple, overlapping effects b. are active in developing plant embryos c. are active in adult plants d. may have different effects in different tissues e. all of the above

_____________is the hormone in most rooting compounds. a. Gibberellin b. Auxin c. Cytokinin d. ABA

Which of the following statements is false? a. Auxin and gibberellin promote stem elongation. b. Cytokinin promotes cell division in shoot tips. c. Abscisic acid promotes water loss and dormancy. d. Ethylene promotes fruit ripening and abscission.

Which combination of hormones is best for promoting lateral root growth? a. A high auxin level and low ABA and cytokinin levels b. A low auxin level and high ABA and cytokinin levels c. A high level of auxin, ABA, and cytokinin

Ethylene differs from other hormones in that it __________. a. is a gas b. participates in defense c. operates during ripening d. none of the above

Heliotropism may be related to ____________. a. phototropism b. gravitropism c. photoperiodism d. a and \(c\)

Sunlight resets biological clocks in plants by activating and inactivating ___________. a. phototropins b. phytochromes c. cryptochromes d. chlorophylls e. \(b\) and \(c\) f. all of the above

In some plants, flowering is a _________ respones. a. phototropic b. gravitropic c. photoperiodic d. thigmotropic

Stomata close in response to __________. a. \(A B A\) b. nitric oxide c. bacteria d. all of the above

Match the response with its main trigger. $$ \text {________phototropism} \quad \quad\quad\quad\quad \text {a. contact with an object} $$ $$ \text {________gravitropism} \quad \quad\quad\quad\quad \text {b. blue light} $$ $$ \text {________thigmotropism} \quad \quad\quad\quad\quad \text {c. a long period of cold} $$ $$ \text {________photoperiodism} \quad \quad\quad\quad\quad \text {d. gravity} $$ $$ \text {________vernalization} \quad \quad\quad\quad\quad \text {e. sun position} $$ $$ \text {________heliotropism} \quad \quad\quad\quad\quad \text {f. night length} $$

Match the hormone with the characteristic. $$ \text {________ethylene} \quad \quad\quad\quad\quad \text {a. efflux carriers set up gradients} $$ $$ \text {________cytokinin} \quad \quad\quad\quad\quad \text {b. produced in positive and negative feedback loops} $$ $$ \text {________auxin} \quad \quad\quad\quad\quad \text {c. affects expression of more genes than any other hormone} $$ $$ \text {________gibberellin} \quad \quad\quad\quad\quad \text {d. works antagonistically to auxin in apical dominance} $$ $$ \text {________ABA} \quad \quad\quad\quad\quad \text {e. big in stems} $$ $$ \text {________nitric oxide} \quad \quad\quad\quad\quad \text {f. active in bursts} $$