What does the given diagram of enzyme action represent?

Steroid hormones are derived from . . . . . . .

What is the role of a second messenger in the mechanism of protein hormone action?

According to the accepted concept of hormone action,if receptor molecules are removed from target organs,what will be the effect?

Which one of the following pairs of hormones are the examples of those that can easily pass through the cell membrane of the target cell and bind to a receptor inside it (mostly in the nucleus)?

What are intracellular receptors?