Biological Role — Na, K, Ca, Mg
s-block Elements
5
JEE Qs
8%
Hard
45
min
Thoroughly memorize the specific biological function of each ion (Na+, K+, Ca2+, Mg2+) and differentiate their roles, paying special attention to the Na+/K+ pump mechanism and Ca2+ involvement in multiple physiological processes.
🧮 Key Formulas
✅ Key Points for JEE
- 1Sodium (Na+) is the primary extracellular fluid cation, crucial for maintaining osmotic balance, nerve impulse transmission (action potential generation), and regulating blood pressure. Its movement is tightly linked with the Na+/K+ pump.
- 2Potassium (K+) is the primary intracellular fluid cation, essential for nerve impulse transmission (repolarization), enzyme activation, protein synthesis, and maintaining osmotic pressure within cells. It is actively transported by the Na+/K+ pump.
- 3Calcium (Ca2+) is vital for bone and teeth formation (as hydroxyapatite), muscle contraction, blood coagulation, nerve impulse transmission, and intracellular signaling. Its concentration is regulated by hormones like parathyroid hormone and calcitonin.
- 4Magnesium (Mg2+) acts as an essential cofactor for numerous enzymes, particularly those involved in ATP-dependent reactions (e.g., energy transfer, nucleic acid synthesis, protein synthesis). It stabilizes DNA/RNA and is important for nerve and muscle function.
- 5The Na+/K+ pump (Na+,K+-ATPase) is a crucial membrane protein that actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, consuming ATP. This creates electrochemical gradients essential for nerve impulses, nutrient transport, and maintaining cell volume.
⚠️ Common Mistakes
- ✕Confusing the primary location (intracellular vs. extracellular) and main roles of Na+ and K+ ions, particularly their respective contributions to nerve impulse generation and repolarization.
- ✕Forgetting the diverse roles of Ca2+ beyond just bone formation, such as its involvement in muscle contraction, blood clotting, and nerve signaling.
- ✕Underestimating the importance of Mg2+ as an enzyme cofactor in many metabolic processes, especially those involving ATP.
📝 Practice Questions
See allQ49. List - I List - II Reaction Type of redox reaction (A) Li (I) 589.2 Match List - I with List - II. Choose the correct answer from the options (B) Na (II) 455.5 (C) Rb (III) 670.8 (D) Cs (IV) 780.0 given below : (1) (A)-(II), (B)-(IV), (C)-(III), (D)-(I) (2) (A)-(I), (B)-(IV), (C)-(III), (D)-(II) (3) (A)-(IV), (B)-(II), (C)-(I), (D)-(III) (4) (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
Q40.Ion having highest hydration enthalpy among the given alkaline earth metal ions is: (1) Be2+ (2) Sr2+ (3) Ba2+ (4) Ca2+
Q32.Match List I with List II (A) Slaked lime (I) NaOH (B) Dead burnt plaster (II) Ca ( OH ) 2 (C) Caustic soda (III) Na2CO3 · 10H2O (D) Washing soda (IV) CaSO4 Choose the correct answer form the options given below: (1) (A) - I, (B) - IV, (C) - II, (D) - III (2) (A) - III, (B) - IV, (C) - II, (D) - I (3) (A) - II, (B) - IV, (C) - I, (D) - III (4) (A) - III, (B) - II, (C) -IV, (D) -I
Q33.Choose the correct statement(s): A. Beryllium oxide is purely acidic in nature. B. Beryllium carbonate is kept in the atmosphere of CO2. C. Beryllium sulphate is readily soluble in water. D. Beryllium shows anomalous behavior. Choose the correct answer from the options given below: JEE Main 2023 (01 Feb Shift 1) JEE Main Previous Year Paper (1) A, B and C only (2) B,C and D only (3) A and B only (4) A only
Q40.The correct order of bond enthalpy ( kJ mol–1 ) is: (1) Si −Si > C −C > Sn −Sn > Ge −Ge (2) Si −Si > C −C > Ge −Ge > Sn −Sn (3) C −C > Si −Si > Sn −Sn > Ge −Ge (4) C −C > Si −Si > Ge −Ge > Sn −Sn
Q37. O −O bond length in H2O2 is X than the O −O bond length in F2O2 . The O −H bond length in H2O2 is Y ¯¯ than that of the O −F bond in F2O2 . Choose the correct option for X and Y from the given below. ¯¯ (1) X - shorter, Y− shorter (2) X -shorter, Y -longer (3) X -longer, Y -longer (4) X-longer, Y - shorter
NCERT Chapters
- Class 11 Chemistry Ch 10: The s-Block Elements