Read the following statements about the lac operon of E. coli. (i) The i gene codes for the repressor, which is made all the time (constitutively). (ii) The z gene codes for beta-galactosidase, which hydrolyses lactose into galactose and glucose. (iii) The y gene codes for permease, which increases the permeability of the cell to beta-galactosides. (iv) The letter i in the name of the i gene stands for inducer. (v) Glucose or galactose can act as an inducer of the lac operon. (vi) The regulation of the lac operon by its repressor is called positive regulation. How many of the statements above are correct?