Which of the following plant hormone is responsible for ripening of fruits?

Step 1: Analyze the question The question asks which plant hormone causes fruits to ripen.

Step 2: Explain the concept Plant hormones (growth regulators) control growth, development, and responses to the environment. Each has a main role:

• Gibberellins promote stem elongation, seed germination, and breaking of dormancy.
• Abscisic acid (ABA) inhibits growth, causes seed dormancy, and closes stomata during water stress.
• Ethylene is a gaseous hormone that stimulates fruit ripening and also leaf fall (abscission) and flower senescence.
• Cytokinins promote cell division and delay leaf ageing.

Step 3: Work through the options

• A. Gibberellins: they promote elongation and germination, not ripening.
• B. Abscisic acid: it is a growth inhibitor linked to dormancy and stress, not ripening.
• C. Ethylene: it triggers ripening. It makes fruits soften, change colour, and develop sweetness.
• D. Cytokinins: they stimulate cell division, not ripening.

Step 4: Answer The correct option is **C.

Real-life link: Nigerian traders often put unripe plantains, bananas, or mangoes together in a closed container or covered with leaves. Ripe fruits release ethylene gas, which speeds up ripening of the others. Putting a ripe banana beside unripe ones does the same thing.

Exam tip: Remember "Ethylene = Eripening", or think "ethylene is the only gaseous hormone". Whenever you see "fruit ripening" in a JAMB question, ethylene is the answer.