Biological Importance of Sodium and Potassium - UNSOLVED PRACTICE SET
Chapter: s-Block Elements Alkali and Alkaline Earth Metals | Topic: Biological Importance of Sodium and Potassium
BIOLOGICAL IMPORTANCE OF SODIUM AND POTASSIUM - UNSOLVED PRACTICE SET
Topic: Biological Importance of Sodium and Potassium
Multiple Choice Questions
Q1. The main cation present in extracellular fluid (outside cells) in the human body is:
- K⁺
- Na⁺
- Ca²⁺
- Mg²⁺
Q2. Potassium ions are primarily found in:
- Blood plasma
- Intracellular fluid (inside cells)
- Cerebrospinal fluid
- Lymph
Q3. The sodium-potassium pump (Na⁺/K⁺-ATPase) maintains the concentration gradient by pumping:
- 2 Na⁺ out and 3 K⁺ in
- 3 Na⁺ out and 2 K⁺ in
- 3 Na⁺ in and 2 K⁺ out
- Equal numbers of Na⁺ and K⁺
Q4. A diet deficient in sodium can lead to:
- Hypertension
- Muscle cramps and weakness
- Hyperkalemia
- Bone disorders
Q5. Which of the following is a good dietary source of potassium?
- Table salt
- Bananas and coconut water
- Processed cheese
- Soft drinks
Q6. Excessive intake of sodium is linked to:
- Diabetes
- Hypertension (high blood pressure)
- Rickets
- Anaemia
Short Answer Questions
Q7. What is the role of sodium ions (Na⁺) in nerve impulse transmission? Why is this function critical for the nervous system?
Q8. Explain why potassium is essential for maintaining proper muscle function. What happens when blood potassium levels become too low (hypokalemia)?
Q9. Your grandmother adds extra salt to her food because she says it "gives strength." Explain to her why excessive salt intake can be harmful, especially for people with high blood pressure.
Q10. Why do athletes drink oral rehydration solutions (ORS) containing sodium and potassium after intense physical activity? What do these ions replace?
Q11. The sodium-potassium pump is called an "active transport" mechanism. What does this mean, and why does it require ATP (energy)?
Q12. Coconut water is often called "nature's ORS" in India. Why is it considered beneficial during dehydration or diarrhoea?
Long Answer Questions
Q13. Describe the biological importance of sodium in the human body. Discuss:
(a) Its role in maintaining osmotic pressure and fluid balance
(b) Its function in nerve impulse transmission
(c) Its role in muscle contraction
(d) The daily recommended intake and sources of sodium
(e) Health consequences of sodium deficiency and excess
Q14. Discuss the biological importance of potassium in the human body with reference to:
(a) Maintenance of intracellular fluid balance
(b) Regulation of heart rhythm and blood pressure
(c) Role in muscle contraction and nerve function
(d) The sodium-potassium pump and its significance
(e) Dietary sources of potassium commonly available in India
Q15. India faces a growing burden of non-communicable diseases like hypertension and cardiovascular diseases. The Indian government has initiated programs to reduce salt intake in the population. Discuss:
(a) Why reducing salt (sodium) intake is a public health priority in India
(b) The WHO recommendation for daily salt intake and how it compares with average Indian consumption
(c) Strategies being used to reduce salt in processed foods in India
(d) Why potassium-rich diets (like the DASH diet) are recommended as an alternative approach
Numerical / Application-Based Problems
Q16. The recommended daily intake of sodium for an adult is 2.3 g (equivalent to about 6 g of NaCl). The average Indian consumes about 10 g of salt per day.
(a) Calculate the mass of sodium consumed by an average Indian per day from 10 g of NaCl.
(b) Calculate the percentage excess sodium consumed compared to the recommended intake.
(c) If a person reduces salt intake to 5 g per day, calculate the mass of sodium consumed and state whether it meets the recommendation.
[Given: Atomic masses: Na = 23, Cl = 35.5]
Q17. A standard Oral Rehydration Solution (ORS) packet contains 2.6 g of sodium chloride (NaCl), 1.5 g of potassium chloride (KCl), 2.9 g of trisodium citrate, and 13.5 g of glucose in 1 litre of water.
(a) Calculate the molarity of NaCl and KCl in the ORS solution.
(b) Calculate the total number of moles of sodium ions (Na⁺) present in 1 litre of this ORS.
(c) A child with diarrhoea is advised to drink 200 mL of this ORS every 2 hours. Calculate the mass of potassium ions (K⁺) the child receives in one day (24 hours) if they follow this advice.
[Given: Atomic masses: Na = 23, Cl = 35.5, K = 39]
Q18. In a nerve cell, the concentration of K⁺ inside the cell is about 140 mM (millimolar), while outside it is about 5 mM. For Na⁺, the concentration inside is about 15 mM and outside is about 145 mM.
(a) Calculate the concentration ratio of K⁺ (inside : outside) and Na⁺ (inside : outside).
(b) Using the Nernst equation concept (without calculation), explain why maintaining these concentration gradients is essential for the resting membrane potential.
(c) If the sodium-potassium pump stops working, predict what would happen to the nerve cell's ability to transmit signals.