A person's heartbeat is irregular because their natural pacemaker is faulty. A doctor fits an artificial pacemaker. How does the artificial pacemaker help the person?
It widens the coronary arteries so more blood reaches the heart muscle
It replaces the faulty valves so that blood flows through the heart one way
It sends electrical impulses to the heart muscle so the heart beats regularly
It pumps blood out of the left ventricle when the heart muscle cannot do so
179 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.