27. c). 28. 1½+1½ a). Step wise description with diagram b). It conclusively proved that the genetic material was DNA OR a). Repressor mRNA produces repressor, inducer binds with repressor ; makes repressor inactive ; operator gene becomes active; structural genes z,y,a transcribe mRNA ; LAC – mRNA translates z, y,a genes to give enzymes β- galactosidase , permease and transacetylase. 1½+1½ b). Lactose acts as inducer. OR (a). and (b). 1 ½+½ c). Because resources are pre-stable so carrying capacity controls the population causing the growth curve to be flatter at the end. d) . 1
27. 28. c). a). Step wise description with diagram b). It conclusively proved that the genetic material was DNA OR a). Repressor mRNA produces repressor, inducer binds with repressor ; makes repressor inactive ; operator gene becomes active; structural genes z,y,a transcribe mRNA ; LAC – mRNA translates z, y,a genes to give enzymes β- galactosidase , permease and transacetylase. b). Lactose acts as inducer. OR (a). and (b). c). Because resources are pre-stable so carrying capacity controls the population causing the growth curve to be flatter at the end. d) . 1½+1½ 1½+1½ 1 ½+½ 1
1250565124study_material_of_class_xii_-biology,.docx