Sarcomere - Definition, Structure, Function and Quiz - Biology Dictionary Quiz 1. Which zone of the sarcomere maintains a constant length during contraction? A. Z lines B. A band C. I band D. S zone Answer to Question #1 2. Which of the following contains only actin filament? A. A band B. H band C. I band D. Z line Answer to Question #2 3. Which of the following contains only myosin filament? A. A band B. H band C.