**Core Concept**
The question is testing the understanding of the mechanism of action of various hormones, specifically whether they act through nuclear receptors or membrane-bound receptors. Hormones can be broadly classified into two categories based on their mode of action: steroid hormones, which diffuse through the cell membrane and bind to nuclear receptors, and peptide hormones, which bind to membrane-bound receptors.
**Why the Correct Answer is Right**
Steroid hormones, such as cortisol and aldosterone, diffuse through the cell membrane and bind to intracellular receptors, which then activate gene transcription. This is in contrast to peptide hormones, such as epinephrine and norepinephrine, which bind to membrane-bound receptors, leading to rapid changes in cellular activity through second messenger systems.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because insulin is a peptide hormone that binds to a membrane-bound receptor on the surface of target cells, triggering a cascade of intracellular signaling events.
**Option B:** Incorrect because angiotensin II is a peptide hormone that binds to a membrane-bound receptor, leading to vasoconstriction and increased blood pressure.
**Option C:** Incorrect because growth hormone is a peptide hormone that binds to a membrane-bound receptor, stimulating the production of IGF-1 and promoting growth and development.
**Clinical Pearl / High-Yield Fact**
Steroid hormones, such as cortisol and aldosterone, are lipophilic and can diffuse through the cell membrane, whereas peptide hormones, such as insulin and growth hormone, are hydrophilic and bind to membrane-bound receptors.
**Correct Answer: C. Growth hormone is a peptide hormone that acts through membrane-bound receptors.**
Free Medical MCQs Β· NEET PG Β· USMLE Β· AIIMS
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