Myofilaments myofilaments include actin and myosin are responsible for shortening muscle cells are specific types of microfilaments all of the answers listed are correct.

Answer : All the listed options are correct .

Myofilaments are present in myofibrils, a special component of muscle cell or muscle fibre. They are made of proteins. They are hair like structure so also called as microfilaments .There are two type of myofilaments present :

A) Thick filament : This filament is made of protein known as " Myosin " . Myosin provides elasticity and contractibility to muscles.

B) Thin filament : This filament is made of protein known as " Actin " , which helps in contraction mechanism .

Following are attached diagram for Myofilaments .

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.