B.P.S.C. (TRE-3) July, 2024
Plants appear to bend towards light due to–
aConcentration of auxins at shoot tip
bConcentration of auxins at root tip
cDiffusion of auxins towards the shady side of the shoot✓ Correct
dMore than one of the above
eNone of the above
Explanation
Auxins are synthesized at the tip of the shoot and help cells to elongate for a longer time. When light falls on the plant from one side, auxin diffuses towards the shaded side of the shoot. The higher auxin concentration on the shaded side stimulates the cells there to elongate more (i.e., on the side away from light). Therefore, the plant appears to bend towards the light.
general-science