Groups of alleles associated with the lactose operon are as follows (in order of dominance for each allelic series): repressor, I^s (superrepressor), I⁺ (inducible), and I^- (constitutive); operator, O^c (constitutive, cis^- dominant) and O+ (inducible, cis-dominant); structural, Z⁺ and Y⁺. 

(a) Which of the following genotypes will produce β-galactosidase and β-galactoside permease if lactose is present: 

(1) I⁺O⁺Z⁺Y⁺, 

(2) I−O^cZ⁺Y⁺, 

(3) I^sOcZ⁺Y⁺, 

(4) I^sO⁺Z⁺Y⁺, and 

(5) I^-O⁺Z⁺Y⁺? 

(b) Which of the above genotypes will produce β-galactosidase and β-galactoside permease if lactose is absent? Why?