Refer to the figure below showing the changes that occur when a leaf is about to fall from the stem. In this diagram, an abscission zone has formed.What does that mean for the plant?
A) It has been exposed to red light, changing the shape of its phytochrome protein.
B) It has been exposed to far-red light, changing the shape of its phytochrome protein.
C) It has produced insufficient auxin for abscission to take place.
D) Ethylene will trigger the plant to drop its leaves.
E) Auxin will soon initiate fruit production.

Question

Refer to the figure below showing the changes that occur when a leaf is about to fall from the stem.  In this diagram, an abscission zone has formed.What does that mean for the plant?
A) It has been exposed to red light, changing the shape of its phytochrome protein. 
B) It has been exposed to far-red light, changing the shape of its phytochrome protein. 
C) It has produced insufficient auxin for abscission to take place. 
D) Ethylene will trigger the plant to drop its leaves. 
E) Auxin will soon initiate fruit production.

Quizplus · Accepted Answer

The formation of an abscission zone means that the plant is preparing to shed the leaf. The hormone ethylene is responsible for triggering the process of abscission, which leads to the detachment of the leaf from the stem. Therefore, choice D is the best answer. Choices A, B, and E are unrelated to the process of abscission and can be ruled out. Choice C suggests that a lack of auxin would prevent abscission, but in reality, a decrease in auxin is actually needed for abscission to occur.

Refer to the Figure Below Showing the Changes That Occur