Question

The answer is shown, but can someone explain how to interpret the images too? There are these random plus signs in between the "absent" and "present" for Z and Y.

Answer 1

The correct answer for question 15 is (c). Because when all the regulated genes are present i.e. repressor, promotor and operator genes are active, then in the presence of lactose, RNA polymerase catalyses the transcription process. Whereas in the absence of lactose, repressor protein catalyses by the repressor gene will block the way of RNA polymerase and stop the synthesis of mRNA for the structural genes.

The corrrect answer for question 16 is (b). Because these is lack of structural gene genotype i.e. z and y so in this case it is not possible to synthesize the structural gene.