Study the figure given below and answer the following questions

Study the figure given below and answer the following questions.

(i) Name the molecule X’ synthesised by i gene.How does this molecule get inactivated?
(ii) Which one of the structural genes codes for (beta-galactosidase?
(iii) When will the transcription of this gene stop?

(i) Molecule ‘X is a repressor protein. When an inducer combines with it, it is inactivated.
(ii) ‘z’ gene.
(iii) Transcription of gene stops:
(a) Substrate (lactose) is not available.
(b) Energy source (glucose) is available to the cells.