The following experiment was performed to test the effect of auxin on the plant growth. Five plant seedlings (all growing actively) were prepared as below; they were unilaterally illuminated, and growth was measured after 10 days. Treatments : Plant A: Tip not removed, nothing applied Plant B: Tip removed, nothing applied Plant C: Tip removed, gelatin block with cytokinin was placed on the cut edge Plant D: Tip remov

Step-by-step solution

Auxin is the plant hormone that is synthesized in young stem apex. During day time, auxin redistribution occurs such that the plant side directly exposed to sunlight contains lower auxin concentration than the other side which is not exposed to light. This unequal distribution causes curvature. In plant A, redistribution of auxin leads to curvature, whereas removal of the tip in plant B leads to no auxin synthesis and no curvature. However, in plant D, where gelatine box with auxin is placed due to auxin redistribu