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).

b. lithosphere, asthenosphere, mesosphere   is the answer most likely

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]