What is the location of the product of the $Lac \, y$ gene?

The $lac$ operon is a part of which of the following?

Wild type $E. coli$ cells are growing in a normal medium with glucose. They are transferred to a medium containing only lactose as the sugar. Which one of the following changes takes place?

In $lac$ operon,the regulator gene codes for

Which enzyme is responsible for the transport of lactose into the cell?

The 'Operon model' for gene regulation in bacteria was proposed by: