question_answer 41)

  The role of ethylene and abscissa add is both positive and negative. Justify the statement.

Answer:

                Auxin is an important plant phytohormone required for the growth and development of every plant in its life cycle. (a) Auxin Precursors are raw materials required to initials synthesis of auxins. IIA is synthesised from tryptophan, adenine compounds and derivatives of carotenoids. (b) Anti-Auxins are compounds that inhibit action of auxins, e.g., p-chlorophenoxy isobutyric acid (PCIB), TIBA. (c) Synthetic Auxin These are synthesised not by plants but artificially by man, e.g., 2-4 D (weedicide), NAA, dicamba and IBA, (Indole Butyric Acid) which are natural as well as synthetic auxin.