Choose the incorrect pair.

Match the following:
Column-$A$ | Column-$B$
$(1)$ Auxin | $(I)$ Ripening and maturity of fruits
$(2)$ Gibberellin | $(II)$ Differentiation of xylem elements
$(3)$ Cytokinin | $(III)$ Prevention of genetic and physiological dwarfism
$(4)$ Ethylene | $(IV)$ Found from tumour tissue of tobacco

An apparatus commonly used to demonstrate phototropism is

Briefly describe the general effects of plant hormones.

Fill in the blanks with appropriate word/words.
$(a)$ $A$ phase of growth which is maximum and fastest is $.......$ .
$(b)$ Apical dominance as expressed in dicotyledonous plants is due to the presence of more $.......$ in the apical bud than in the lateral ones.
$(c)$ In addition to auxin,a $.........$ must be supplied to culture medium to obtain a good callus in plant tissue culture.
$(d)$ $.........$ of a vegetative plants are the sites of photoperiodic perception.

In which of the following respects do plant hormones differ from enzymes?