Question

Steroid hormones easily pass through the plasma membrane by simple diffusion because they:

• A. Are water soluble
• B. Contains carbon and hydrogen
• C. Enters through pores
• D. Are lipid soluble

Answer 1

The correct option is D

Are lipid soluble

The correct option is D.

Explanation for the correct option:

1. The plasma membrane of the cell is composed of proteins and phospholipid bilayer.
2. If any substance that is easily soluble in lipid and hydrophobic in nature would be able to pass easily through the membrane.
3. Such as steroids and vitamins like A, D, and E.

Explanation for incorrect options:

Option A:

1. Water-soluble substances and molecules are hydrophilic in nature and do not dissolve in lipids.
2. Moreover, the steroid is not water-soluble.

Option B:

Although, Hydrocarbons are lipid-soluble carbon and hydrogen alone does not play any role in diffusion through the plasma membrane.

Option C:

1. Steroid hormones are complex molecules made of cholesterol and could not easily enter through pores as they're not small in size.
2. Their solubility in fat makes them easily permeable through the plasma membrane.

Final answer:

Hence, steroid hormones easily pass through the plasma membrane by simple diffusion because they are lipid-soluble.