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Multiple Choice
In the autumn, the amount of __________ decreases, rendering the cells of the abscission layer more sensitive to __________.
A
ethylene; auxin
B
gibberellin; abscisic acid
C
cytokinin; abscisic acid
D
gibberellin; auxin
E
auxin; ethylene
Verified step by step guidance
1
Understand the role of auxin and ethylene in plant physiology. Auxin is a plant hormone that promotes cell elongation and growth, while ethylene is involved in the regulation of fruit ripening and leaf abscission.
Recognize that during autumn, the decrease in auxin levels makes the cells of the abscission layer more sensitive to ethylene. This sensitivity leads to the process of leaf abscission, where leaves detach from the plant.
Identify the abscission layer as a specialized layer of cells at the base of the leaf petiole. This layer becomes more sensitive to ethylene as auxin levels decrease.
Consider the environmental changes in autumn, such as shorter daylight hours and cooler temperatures, which contribute to the reduction of auxin production in plants.
Conclude that the correct answer is 'auxin; ethylene' because the decrease in auxin makes the abscission layer more sensitive to ethylene, facilitating the leaf drop process.