Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A detached leaf stays green for days. A matching leaf, sprayed with a cytokinin, stays green for days.
Gibberellins (GA3, from the fungus Gibberella) are terpenes that lengthen the stem, promote bolting, delay senescence and speed malting. Cytokinins are adenine derivatives (kinetin, zeatin) that promote cell division and lateral shoots, overcome apical dominance and delay senescence. A high auxin to cytokinin ratio gives roots and a low ratio gives shoots.
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) days.
Step 2. (b) times as long.
Step 3. (c) The cytokinin delays senescence. It moves nutrients into the leaf, so the leaf does not age.
Answer: days; times; senescence.
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