Question

How many of the following hormones do not enter the target cell?
Iodothyronine, Testosterone, Estradiol, Insulin, Glucagon

• A. 4
• B. 6
• C. 3
• D. 2

Answer 1

The correct option is D 2

Insulin and glucagon are protein hormones. They are water-soluble, and hence interact with membrane bound hormone receptors and generate second messengers. Thus, these hormones do not enter the target cell directly.
Hormones like iodothyronines, testosterone, and estradiol (estrogen) interact with the hormone recpetors present within the cell (intracellular receptors). Thus, they enter the target cell.