A student notices that a potted plant kept in a dark cupboard grows tall and pale with very long internodes compared to one kept in sunlight. This is most directly influenced by the action of which hormone, which promotes cell elongation?
Question
A student notices that a potted plant kept in a dark cupboard grows tall and pale with very long internodes compared to one kept in sunlight. This is most directly influenced by the action of which hormone, which promotes cell elongation?
Insulin
Auxin
Adrenaline
Thyroxin
Answer
Auxin
Detailed Explanation
Auxin promotes cell elongation in stems, and in the absence of light to redistribute it, plants can show excessive, pale elongation (etiolation) as they grow tall seeking light.