Part 7: Mechanism of Hormone Action – Peptide vs Steroid Hormones, Receptors, Signal Transduction
Part 7 (25 MCQs) on Mechanism of Hormone Action – Peptide vs Steroid Hormones, Receptors, Signal Transduction from Chapter 22: Chemical Coordination and Integration (NCERT Class 11 + NEET UG).
Part 7: Mechanism of Hormone Action – Peptide vs Steroid Hormones, Receptors, Signal Transduction
Q1. Peptide hormones act through:
a) Intracellular receptors
b) Cell surface receptors
c) Nuclear receptors only
d) Mitochondrial receptors
Answer: b) Cell surface receptors
- ✅ Peptide hormones cannot cross plasma membrane → act via membrane receptors.
Q2. Steroid hormones act through:
a) Cell membrane receptors
b) Intracellular/nuclear receptors
c) Synaptic junctions
d) Enzyme-linked receptors only
Answer: b) Intracellular/nuclear receptors
- ✅ Lipid-soluble steroids diffuse into cell → bind intracellular receptors.
Q3. Which of the following is a peptide hormone?
a) Cortisol
b) Testosterone
c) Insulin
d) Estradiol
Answer: c) Insulin
- ✅ Insulin is a peptide hormone, others are steroid-based.
Q4. Which of the following is a steroid hormone?
a) Insulin
b) Glucagon
c) Cortisol
d) ADH
Answer: c) Cortisol
- ✅ Cortisol = steroid (cholesterol derivative).
Q5. Thyroxine belongs to which class of hormones?
a) Steroid
b) Peptide
c) Iodinated amino acid derivative
d) Catecholamine
Answer: c) Iodinated amino acid derivative
- ✅ Thyroxine is derived from tyrosine + iodine.
Q6. The “second messenger” concept is related to:
a) Peptide hormones
b) Steroid hormones
c) Thyroid hormones
d) None
Answer: a) Peptide hormones
- ✅ Peptide hormones act via cAMP, IP₃, DAG as second messengers.
Q7. Which molecule is a second messenger in hormone action?
a) ATP
b) cAMP
c) DNA
d) RNA
Answer: b) cAMP
- ✅ cAMP mediates many peptide hormone actions (e.g., glucagon, adrenaline).
Q8. The first messenger in hormone action is:
a) Hormone itself
b) cAMP
c) Ca²⁺
d) ATP
Answer: a) Hormone itself
- ✅ Hormone binds receptor = first messenger.
Q9. Which ion acts as a second messenger?
a) Na⁺
b) K⁺
c) Ca²⁺
d) Mg²⁺
Answer: c) Ca²⁺
- ✅ Intracellular Ca²⁺ is a second messenger (muscle contraction, secretion).
Q10. Protein kinases are activated by:
a) cAMP
b) DNA
c) Steroid hormones
d) RNA
Answer: a) cAMP
- ✅ cAMP activates protein kinases → phosphorylation cascade.
Q11. Steroid hormone–receptor complex binds to:
a) Plasma membrane
b) Mitochondria
c) DNA in nucleus
d) Ribosomes
Answer: c) DNA in nucleus
- ✅ Steroid hormone complex acts as transcription factor.
Q12. Hormones that act via cell membrane receptors are:
a) Steroid hormones
b) Peptide hormones
c) Thyroid hormones
d) All lipid-soluble hormones
Answer: b) Peptide hormones
- ✅ Peptides cannot enter cells → act through membrane receptors.
Q13. Catecholamines act via:
a) Nuclear receptors
b) Membrane receptors and cAMP
c) Direct binding to DNA
d) Enzyme repression
Answer: b) Membrane receptors and cAMP
- ✅ Epinephrine/norepinephrine → GPCR → cAMP pathway.
Q14. Steroid hormones are soluble in:
a) Water
b) Lipids
c) Both water and lipids
d) Plasma proteins only
Answer: b) Lipids
- ✅ Lipid solubility allows diffusion through plasma membrane.
Q15. ADH acts on kidney tubules via:
a) Nuclear receptors
b) cAMP as second messenger
c) DNA binding
d) Direct gene activation
Answer: b) cAMP as second messenger
- ✅ ADH → activates cAMP → aquaporin channels inserted.
Q16. Insulin increases glucose uptake by:
a) Activating glucose transporters
b) Increasing gluconeogenesis
c) Increasing glycogenolysis
d) Blocking glycolysis
Answer: a) Activating glucose transporters
- ✅ Insulin → GLUT4 transporter translocation to membrane.
Q17. Which hormone increases glycogenolysis via cAMP pathway?
a) Insulin
b) Glucagon
c) Thyroxine
d) Estrogen
Answer: b) Glucagon
- ✅ Glucagon → adenylate cyclase → cAMP → glycogen breakdown.
Q18. The IP₃-DAG pathway is associated with:
a) Steroid hormones
b) Peptide hormones
c) Thyroid hormones
d) Adrenal steroids
Answer: b) Peptide hormones
- ✅ Many peptide hormones use IP₃-DAG → Ca²⁺ release.
Q19. Hormone–receptor interaction follows the principle of:
a) Lock and key model
b) Competitive inhibition
c) Endocytosis
d) Diffusion
Answer: a) Lock and key model
- ✅ Specific receptor–hormone binding is highly selective.
Q20. Steroid hormones act slower than peptide hormones because:
a) They dissolve poorly in plasma
b) They act at gene transcription level
c) They cannot enter cells easily
d) They do not bind receptors
Answer: b) They act at gene transcription level
- ✅ Steroid hormones → gene transcription → protein synthesis (slow but long-lasting).
Q21. Peptide hormones act faster because:
a) They directly bind DNA
b) They use second messengers
c) They bind intracellular receptors
d) They alter genes permanently
Answer: b) They use second messengers
- ✅ cAMP/IP₃ → rapid effects of peptide hormones.
Q22. Epinephrine hormone action is mediated by:
a) Intracellular receptor binding
b) Adenylate cyclase and cAMP
c) Gene transcription
d) Mitochondrial DNA
Answer: b) Adenylate cyclase and cAMP
- ✅ Epinephrine → GPCR → adenylate cyclase → cAMP.
Q23. Steroid hormone receptors are located in:
a) Plasma membrane
b) Cytoplasm and nucleus
c) Endoplasmic reticulum
d) Ribosomes
Answer: b) Cytoplasm and nucleus
- ✅ Steroid receptors exist intracellularly.
Q24. Second messenger system was first demonstrated for:
a) Insulin
b) Glucagon
c) Steroid hormones
d) Thyroxine
Answer: b) Glucagon
- ✅ Glucagon–cAMP mechanism was first described.
Q25. Which is NOT a second messenger?
a) cAMP
b) IP₃
c) Ca²⁺
d) Insulin
Answer: d) Insulin
- ✅ Insulin is a hormone (first messenger), not a second messenger.
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