A farmer who wants to keep seeds for three years before planting and wants to prevent them from sprouting uses

Analyze the question: The farmer wants to store seeds for a long time (three years) and stop them from germinating. So we need the plant hormone that promotes seed dormancy and inhibits sprouting.

Concept: Plant hormones and their roles

• Auxin: promotes cell elongation, apical dominance, and root formation. It also helps prevent leaf and fruit fall.
• Gibberellins: break seed dormancy and stimulate germination and stem elongation. This is the opposite of what the farmer wants.
• Abscisin (abscisic acid, ABA): a growth inhibitor. It maintains seed and bud dormancy, causes leaf fall (abscission), and closes stomata during water stress.
• Cytokinins: promote cell division, delay leaf ageing, and help break dormancy of lateral buds.

Solution:

1. The goal is to prevent sprouting, so we need a hormone that keeps seeds dormant.
2. Gibberellins and cytokinins stimulate growth and germination, so they are ruled out.
3. Auxin mainly promotes growth in shoots and does not maintain seed dormancy, so it is ruled out.
4. Abscisin (abscisic acid) is the hormone that induces and maintains dormancy and inhibits germination.

Answer: C. abscisin

Exam tip: Remember ABA = "Always Block Accelerating growth". Abscisic acid is the "stress and sleep" hormone that causes dormancy, leaf fall, and stomatal closure. Gibberellins are the "germination" hormone, so they work as opposites in questions on dormancy.