Knockout of the CTR1 gene in Arabidopsis causes the plant to continuously perform this process. For 10 points each:
[10h] Name this process in which a seedling inhibits its root elongation, increases its shoot thickness, and tightens its apical hook in the presence of ethylene.
ANSWER: triple response [accept constitutive triple response 1]
[10e] In seedlings, ethylene signalling causes microtubules to change orientation and induces a lateral shift in deposition of this polymer. This polymer is the main component of a plant’s cell wall.
ANSWER: cellulose [or C6H10O5; reject “hemicellulose”]
[10m] Ethylene also acts against auxin to promote this process, which occurs following a “maintenance” and “induction” phase. A hormone named for this process induces stomatal closure during drought stress.
ANSWER: leaf abscission [or leaf shedding; accept fruits or flowers in place of “leaf”; prompt on abscisic acid or abscisin or ABA by asking “what process is that hormone named after?”; prompt on leaves falling off from a plant; prompt on leaf senescence; prompt on defoliation]
<Kane Nguyen, Biology>