Question

25. In a rare biological example of positive feedback, an increase in ethylene production triggers more ethylene production. Explain how this effect, and the fact that ethylene is a gas, could help to coordinate the timing of the ripening process on a plant.

26. It is imperative that grocery stores have ripe fruit at the store for consumers to buy, but it is easier to transport produce in an unripened state. Explain how the commercial use of ethylene might help to solve this dilemma.

Answer 1

25. Ethylene is a gas hormone produced by fruits when they ripe. The produced ethylene further activates EIN3 gene (Ethylene sensitive3 gene), a transcription factor that regulates the activation of ripening genes like RIN, TAGL1, NAC, etc. The ripening gene further activates ACO1 and ASC2 gene that synthesizes ethylene from the ripe fruits and this loop goes on and helps in ripening fruits in the plant in a positive feedback manner.

26. Fruits are at their best when they ripen. In recent years the consumption of fruits has increased due to the awareness of its health benefits. In order to meet the fruit consumption requirement, fruits are transported distant places even intercontinental. However, the majority of the fruits tend to perish and have short-lived after ripe and as a result, can't be transported after ripening. Therefore, in order to avoid fruit spoilage during long distant transportation, harvesting raw fruits and ripen them artificially before sale to save the cost of spoilage. Ethylene gas is a natural hormone that is synthesized by ripe fruits. The ethylene gas generated by ripe fruit help in the ripening of the neighboring fruits in a positive feedback loop.