Question

Pregnenolone and progesterone form the precursors for all except:

• A. Vitamin D
• B. Protein hormone
• C. Steroid hormones
• D. Eicosanoids

Hint:

Steroid precursors:
Pregnenolone, progesterone.
Products: steroid hormones, vitamin D, eicosanoids.
Protein hormones: separate synthesis.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Pregnenolone and progesterone are steroid precursors.
They are used for the synthesis of specific compounds.

Step 2: Key Formula or Approach:
No specific formula.
Need to know the products derived from pregnenolone.

Step 3: Detailed Explanation:
Pregnenolone and progesterone are precursors for:
- Steroid hormones (cortisol, aldosterone, androgens, estrogens)
- Vitamin D
- Eicosanoids (through arachidonic acid pathway)
They are NOT precursors for protein hormones.
Protein hormones are synthesized from amino acids.
Thus, protein hormone is the exception.

Step 4: Final Answer:
Pregnenolone and progesterone are not precursors for protein hormones.
Hence, the correct option is (B).