NEETZoologyBody Fluids and Circulation
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The heart beat rate of an individual can be determined by counting the number of QRS complexes in a standard ECG over a given time period. Reason (R): The QRS complex represents the depolarisation of the ventricles, which initiates ventricular contraction. In the light of the above statements, choo
Options
- AAssertion (A) is false but Reason (R) is true.
- BAssertion (A) is true but Reason (R) is false.
- CBoth Assertion (A) and Reason (R) are true but Reason (R) is NOT the correct explanation of Assertion (A).
- DBoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Correct answer
D. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Step-by-step solution
According to NCERT, by counting the number of QRS complexes that occur in a given time period, one can determine the heart beat rate of an individual. This is because the QRS complex represents the electrical depolarisation of the ventricles, which leads to ventricular contraction. Ventricular contraction is the primary mechanical event that pumps blood out of the heart, corresponding to a single heartbeat. Therefore, both Assertion and Reason are true, and the Reason correctly explains the Assertion. Answer: Both