Given below are two statements.

Statement I  : Nerve impulse transmission along an axon is unidirectional.

Statement II : Axonal membrane is impermeable to negatively charged proteins present in the axoplasm.

In light of the above statements, choose the correct answer from the options given below.

Statement I is correct. Although action potentials can be initiated at various points along the axon in experimental conditions, under normal physiological conditions, nerve impulses (action potentials) are typically transmitted in one direction—from the cell body (soma) down the axon to the axon terminals. This unidirectional flow is due to the refractory period that follows the passage of an action potential, preventing the impulse from traveling backward.

Statement II is also correct. The axonal membrane is indeed impermeable to large negatively charged proteins within the axoplasm. These proteins contribute to the negative charge inside the neuron but cannot pass through the axonal membrane, helping maintain the membrane potential.