Ethylene Triggers the Ripening of Fruit for Many Plant Species

question 20

Multiple Choice

Ethylene triggers the ripening of fruit for many plant species but does not seem to play an important role for the ripening of grapes. Scientists hypothesized that the trigger for the ripening of grape fruits is abscisic acid (ABA) . They sprayed unripe Cabernet Sauvignon grapes with different concentrations of ABA and tracked several fruit characteristics over time: percent of fruits that are purple, concentration of anthocyanin (a purple pigment) per fruit, weight of each fruit, and total soluble solids per fruit as measured by °Brix. °Brix measurements indicate the amount of sugar in the fruit, and determine how much alcohol a wine will have. Higher values of each measurement indicate a greater degree of ripening. The scientists' results are shown in these four graphs.
Source: Wheeler, S., Loveys, B., Ford, C., & Davies, C. (2009) . The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid. Australian Journal of Grape and Wine Research, 15(3) , 195-204.
-What is the difference between fruits sprayed with the low (5 mg/L) concentration of ABA and the high (400 mg/L) concentration of ABA?

• A) The high concentration results in the earlier occurrence of colored fruit and maximum fruit size.
• B) The high concentration induces an earlier occurrence of the maximum amount of anthocyanin (purple pigment).
• C) The high concentration has smaller fruit until the end of the experiment.
• D) The high concentration produces fruit with less sugar at the end of the experiment.

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