Circulatory System

Step 1: Understanding the Concept: An Electrocardiogram (ECG) is a graphical representation of the electrical activity of the heart during a standard cardiac cycle.
Step 2: Key Formula or Approach: Associate each wave of the ECG (P, QRS complex, T) with its corresponding electrical event (depolarization or repolarization) in the atria or ventricles.
Step 3: Detailed Explanation: A standard ECG consists of several waves.
The 'P' wave represents the electrical excitation or depolarisation of the atria, which leads to the contraction of both atria.
Therefore, Statement I is incorrect because it falsely states that the P wave represents ventricular depolarisation (which is actually represented by the QRS complex).
The 'T' wave represents the return of the ventricles from an excited to a normal resting state, which is called repolarisation.
Therefore, Statement II is completely correct.
Step 4: Final Answer: Statement I is wrong but Statement II is correct.