A Level Biology Practice Exam

What is unique about myogenic muscle?

1. It is voluntary and controlled by the nervous system

2. It contracts in response to external stimuli only

3. It has its own intrinsic rhythm

4. It requires nerve signals for every contraction

The correct answer is: It has its own intrinsic rhythm

Myogenic muscle is characterized by its ability to contract independently due to its own intrinsic rhythm. This means that it has an innate capacity to generate electrical signals that stimulate contraction without relying on external neural input. This property is crucial, especially in cardiac muscle, where continuous rhythmic contraction is essential for maintaining an effective heartbeat. The other options do not apply to myogenic muscle. For instance, myogenic muscle is not voluntary and does not require constant nervous system control; rather, it operates autonomously. It also does not rely solely on external stimuli for contraction, as its rhythm is self-generated. Moreover, while nerve signals may influence myogenic muscle function (for instance, modulating the heart rate), they are not required for each contraction to occur, as the muscle can contract on its own.