Which of the statements explains why there is a delay in the conduction of the electrical impulse at the atrioventricular node (AVN)?
To allow the ventricles to fill completely before they contract.
To prevent the ventricles from contracting at the same time as each other.
To allow blood to flow directly from the vena cava into the ventricles.
To ensure that the semilunar valves open during atrial systole.
15 exam-style questions on OCR A A Level Biology Transport in animals. Each one has a worked solution and a mark scheme showing where the marks go.