IB Biology HL B3.3.3 Hl Titin and Antagonistic Muscles Questions
Practise explaining how titin centres myosin and recoils like a spring to prevent overstretching, then describe how opposing muscles move a joint.
Syllabus
First assessment 2025
Course
Biology HL
Level
HL
Exam points
Explain how titin centres myosin in a sarcomere, stores elastic potential energy, recoils after stretching and limits overstretching.
Explain why antagonistic muscles are required: one muscle actively contracts to pull a joint while the opposing muscle relaxes, producing opposite movements.
Apply flexor-extensor opposition to elbow or insect-joint diagrams by identifying biceps/triceps actions, attachment and the resulting flexion or extension.
The diagram shows a section through part of the leg of an insect and antagonistic muscles X and Y. The tibia moves in the direction shown by the arrow when the muscle is flexing.
Question (a)
(a)
Outline a reason for the muscles being described as antagonistic.
[ 1 ]
cause opposite movements / pull in opposite directions / when one contracts the other relaxes;