Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?
a. glucose
b. cellulose
c. starch
d. estrogen
e. glycerol

Estrogen.

Explanation:

Plasma membrane is made of lipids and proteins. The lipids are arranged in bilayers and proteins are embedded or may span the lipid bilayer. The carbohydrates are attached on the surface of the membrane.

The molecules that are lipophillic in nature can easily diffuse through the plasma membrane. Among the molecules listed in the question, estrogen is highly lipophillic in nature and can easily cross the lipid bilayer of the plasma membrane.

Thus, the correct answer is option (d).

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."