Final answer:
Active transport in Malpighian tubules ensures intracellular potassium (K+) concentration remains constant, as K+ ions are moved into the cell against their concentration gradient by the sodium-potassium pump, which uses ATP.
Step-by-step explanation:
Active transport in the Malpighian tubules is crucial to maintaining ionic and osmotic balances within an organism. Specifically, through the mechanism of the sodium-potassium pump, potassium ions (K+) are moved into the intracellular space against their concentration gradient, demonstrating the body's ability to regulate ion concentrations actively. The sodium-potassium pump actively transports two K+ ions into the cell while exporting three sodium ions (Na+) out of the cell. This active transport process consumes ATP (Adenosine Triphosphate). Subsequently, it helps in generating and maintaining an electrochemical gradient across the cell membrane.
The question regarding the active transport of K+ in Malpighian tubules leads to the conclusion that intracellular K+ concentration remains constant. This is because the active transport mechanisms involved in the process ensure that K+ ions are adequately moved into the cells to balance the ionic distribution between the intracellular and extracellular environments. Hence, the correct answer is:
- (a) Intracellular K+ concentration remains constant
This dynamic process enables organisms to maintain essential physiological functions, such as nerve impulse transmission, muscle contraction, and the tightening of Malpighian tubules that affect urine formation and excretion.