Direction: In the following questions, you have three brief passages with 5 questions following each passage. Read the following passage carefully and choose the best answer to each question out of the four alternatives.
Passage
The heart is one of the most vital components of the human body. The heart of the human body has the continuous job to keep oxygen-rich blood flowing through the body. All the body’s cells need a constant supply of oxygen, particularly in the brain. The brain cells live only four to five minutes after the oxygen is cut off and death comes to the entire body. Heart disease can result from damage to the heart muscles, the valves or the pacemaker. If the muscle is damaged, the heart is unable to pump properly. If the valves are damaged, blood cannot flow normally. Dr. John Gibbon of U.S.A. developed a machine in 1953 that could take over temporarily from the heart. Surgeons had the chance to repair or replace a defective heart. Many patients have had plastic valves inserted in their hearts when their hearts were faulty. Many people are now being kept alive with tiny battery operated pacemakers.