Identify the plant growth promoters and plant growth inhibitors.

Which of the following are added as growth promoters in culture media?
$(i)$ Ethylene
$(ii)$ Abscisic acid
$(iii)$ Gibberellin
$(iv)$ Auxin
$(v)$ Cytokinin

Plants are killed in water by frost due to:

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.

Which of the following are plant growth promoters?

Some flowers $(e.g., Oxalis)$ open in the morning and close during evening because of