Q.45 Which of the following statements are related to steroidal hormones?

1. Cholesterol is the precursor of steroidal hormones.
2. Steroidal hormones include oxytocin and prolactin.
3. Steroidal hormones cannot cross the cell membrane without any receptor.
4. StAR protein helps in transport of cholesterol from outer to inner mitochondrial membrane for steroid biosynthesis.

Choose the correct answer from the options given below:

1. A and B only
2. A and C only
3. A and D only
4. B and C only

   Echinoderms were last query; now steroidal hormones MCQ tests endocrine biology basics for exams like NEET. This question checks cholesterol links, examples, membrane crossing, and biosynthesis transport. The right pick excludes wrong hormone types and membrane myths.

   Correct Answer: C (A and D only)

   Steroid hormones derive from cholesterol via key steps; options B and C fail on examples and diffusion.

   Option A: Cholesterol Precursor – Correct

   Steroid hormones like cortisol, estrogen, and testosterone all start from cholesterol, the lipid backbone modified by enzymes in adrenal glands, gonads, and placenta. This universal precursor gives their four-ring structure, enabling fat-soluble actions.

   Option B: Oxytocin and Prolactin – Incorrect

   Oxytocin (uterine contraction, milk ejection) and prolactin (lactation) are peptide hormones from the pituitary, not steroids. Steroids include glucocorticoids (cortisol), mineralocorticoids (aldosterone), and sex steroids (testosterone, estradiol)—water-soluble peptides bind surface receptors instead.

   Option C: Membrane Crossing Claim – Incorrect

   Steroid hormones freely diffuse across cell membranes due to lipid solubility, binding intracellular receptors in cytoplasm or nucleus—no surface receptor or help needed. This contrasts peptide hormones needing membrane receptors and second messengers.​

   Option D: StAR Protein Role – Correct

   StAR (Steroidogenic Acute Regulatory) protein shuttles cholesterol from outer to inner mitochondrial membrane, the rate-limiting step for steroid synthesis. Inside mitochondria, cholesterol converts to pregnenolone via CYP11A1, kicking off hormone pathways.​

   Exam Relevance

   Mastering steroidal hormones MCQ clarifies hormone classes for deuterostome/endocrine topics in NEET or zoology. Key contrast: lipid-soluble steroids (genomic, slow) vs. peptide (rapid signaling). Recall: cholesterol → StAR → pregnenolone pathway.