Read the following statements regarding the mechanism of muscle contraction: A. A motor neuron along with the muscle fibres connected to it constitutes a motor unit. B. During muscle contraction, the 'A' bands get reduced in length whereas the 'I' bands retain their length. C. Calcium ions bind to a subunit of troponin on actin filaments and remove the masking of active sites for myosin. D. The myosin head acts as an

Step-by-step solution

Statement A is correct. A motor neuron along with the muscle fibres connected to it constitutes a motor unit. Statement B is incorrect. During muscle contraction, the 'I' bands get reduced in length, whereas the 'A' bands retain their length. Statement C is correct. Calcium ions bind to a specific subunit of troponin on the actin filaments, which brings about a conformational change and removes the masking of active sites for myosin. Statement D is correct. The globular head of myosin acts as an ATPase enzyme and h