Animated Solution for Chemistry - s and p-Block Elements: The correct statement(s) among I to III with respect to potassium ions that are abundant within the cell fluids is/are I. They activate many enzymes. II. They participate in the oxidation of glucose to produce ATP. III. Along with sodium ions, they are responsible for the transmission of nerve signals.

When we study the s-block elements in chemistry, it is easy to get lost in ionization enthalpies and flame tests. However, the true magic of these elements, particularly sodium ($Na$) and potassium ($K$), lies in their profound biological importance.

Imagine a living cell as a highly fortified castle. Inside the castle walls (the intracellular fluid), potassium ions ($K^{+}$) are the absolute rulers. They are the most abundant positive ions inside the cell. Conversely, outside the castle walls (the extracellular fluid), sodium ions ($N{a}^{+}$) dominate the landscape. This specific distribution is not an accident; it is the foundation of life itself.

The Enzyme Activator

Let us evaluate the first statement: Do potassium ions activate enzymes?

Yes, absolutely! Inside the cell, many vital enzymes are essentially dormant until a potassium ion binds to them. $K^{+}$ acts as a crucial cofactor. For instance, pyruvate kinase, a key enzyme in the glycolysis pathway, requires potassium to function properly. Without the abundant presence of $K^{+}$ in the intracellular fluid, these biological machines would grind to a halt, bringing cellular metabolism to a standstill.

Powering the Cell

Moving to the second statement: Do they participate in the oxidation of glucose to produce ATP?

Because potassium is responsible for activating enzymes like pyruvate kinase, it plays a direct and indispensable role in the oxidation of glucose. Glycolysis and the subsequent Krebs cycle are the primary pathways through which a cell breaks down glucose to harvest energy.

This energy is stored in the form of ATP (Adenosine Triphosphate), the universal energy currency of the cell. Therefore, by enabling the enzymes that drive these pathways, potassium ions are fundamentally participating in ATP production. Statement II is perfectly correct.

The Electric Highway

Finally, let us look at the third statement: Are they responsible for the transmission of nerve signals?

Have you ever wondered how a thought travels from your brain to your muscles? It happens via electrical impulses, and this is where the famous Sodium-Potassium Pump ($N{a}^{+}/K^{+}$ pump) comes into play.

This pump is a fascinating protein embedded in the cell membrane. It constantly uses ATP to pump $3N{a}^{+}$ ions out of the cell and $2K^{+}$ ions into the cell against their concentration gradients. Because more positive charge is leaving the cell than entering, the inside of the cell becomes negatively charged relative to the outside.

This creates an electrical gradient known as the resting membrane potential. When a nerve is stimulated, ion channels open, allowing these ions to rush back across the membrane, creating an electrical spike called an action potential. Thus, potassium, working in tandem with sodium, is the very reason our nervous system can transmit signals. Statement III is undeniably correct.

By analyzing the biological roles of potassium, we have established that it activates enzymes, facilitates the production of ATP, and is essential for nerve signal transmission.

Since all three statements (I, II, and III) are scientifically accurate, the correct choice is Option (b). Chemistry and biology are truly two sides of the same coin!