There are two factors which determine an individual’s intelligence. The first is the sort of brain he is born with Human brains differ considerably, some being more capable than others. But no matter how good a brain he has to begin with, an individual will have a low order of intelligence unless he has opportunities to learn. So the second factor is what happens to the individual---the sort of environment in which he is reared. If an individual is handicapped environmentally, it is likely that his brain will fail to develop and he will never attain the level of intelligence of which he is capable
The importance of environment in determining an individual’s intelligence can be demonstrated by the case history of the identical twins, Peter and Mark X Being identical, the twins had identical brains at birth, and their growth processes were the same . When the twins were three months old, their parents died , and they were placed in separate foster homes. Peter was reared by parents of low intelligence in an isolated community with poor educational opportunities. Mark was reared in the home of well-to-do parents who had been to college. He was read to as a child, sent to good schools, and given every opportunity to be stimulated intellectually. This environmental difference continued until the twins were in their late teens, they were given tests to measure their intelligence Mark’s I Q was 125, twenty-five points higher than the average and fully forty points higher than his identical brother. Given equal opportunities, the twins, having identical brains, would have tested at roughly the same level.
11 The selection can best be titled________
A) Measuring Your Intelligence B) Intelligence and Environment
C) The Case of Peter and Mark D) Pitfalls for the I Q Test
12 The best statement of the main idea of this passage is that _______
A) human brains differ considerably
B) the brain a person is born with is important in determining his intelligence
C) environment is crucial in determining a person’s intelligence
D) a person who is handicapped environmentally will never attain the level of intelligence of which he id capable
13 According to the passage, the average I Q is ____
A) 85 B)100 C)110 D)125
14 The case history of the twins appears to support the conclusion that______
A) individuals with identical brains seldom test at the same level
B) an individual’s intelligence is determined solely by his environment
C) children reared under average conditions possess average intelligence
D) lack of opportunity hinders the growth of intelligence
15 This passage suggests that an individual’s I Q____
A) can be predicted at birth B) is inherited from his parents
B) stays the same throughout his life D) can be increased by education

11B
12C
13B
14D
15D