<em>C. Binding to the operator.</em>
Explanation:
When the repressor starts binding to the operator, it can not transcribe, or make mRNA. This makes it so the RNA polymerase can't go onto the promoter and bind to it, which is a crucial part in making mRNA. The operator functions by making sure the certain DNA gets made, so it is very important. The lac repressor will turn off the expression of the lac genes by binding to the operator.
Answer:
cell membrane
Explanation
It's the outer living boundary of animal cells. It's made of lipid and protein. Plasma Membrane is a mosaic of phospholipids, cholesterol, and proteins, the proteins in plasma membrane regulates the coming/going of substances into/out of the cell.
This illustrates that the two animals (the horse and the lion) do not eat the same type of food. This could also show one way of classification between different animal species.