5. Isomers are molecules that have the same num- ber of the same elements, but in a different arrangement. Which one of the following is an isomer of 2-propanol (shown below), which contains Carbon (C), Hydrogen (H) and Oxygen (O)? a. b. c. d. e. Questions 6 and 7 are based on the following passage. The rectilinear propagation of light and the law of reflection had been observed long before the development of modern theories that correctly explain these observations. Rectilinear propaga- tion of light refers to the fact that light travels in straight lines. Hero of Alexandria, who lived around the first century, explained these obser- vations by stating that light travels along the shortest allowed path. It wasn’t until 1657 that Pierre de Fermat rejected Hero’s shortest-path theory and showed that light propagates along the path taking the least time. From his princi- ple of least time, Fermat re-derived the law of reflection, as well as the law of refraction. This principle played an important role in the devel- opment of quantum mechanics. 6. The passage shows that a. reflection and refraction can’t be explained by the same theory. b. the term reflection means that light travels in straight lines. c. Hero of Alexandria had insight into quantum mechanics. d. scientists develop theories to explain the phe- nomena they observe in nature. e. light travels along the shortest allowed path. 7. Which general statement about science is NOT supported by the passage? a. A scientific finding sometimes plays a role in other scientific findings. b. Centuries can pass before an observation is correctly explained by science. c. Theory should not be based on experimental evidence. d. Different scientists do not always come up with the same explanation for an observation. e. A scientific theory should be in agreement with observations. 8. Lung cancer accounts for over 30% of all can- cers. Smokers are 90% of lung cancer victims. Lung cancer is rare in societies that don’t smoke. Which is NOT a likely consequence of these statistics? a. Most smokers don’t quit because they experi- ence withdrawal symptoms. b. Congress passed a bill requiring tobacco com- panies to label their product as harmful. c. The percentage of smokers dropped after these figures were made public. d. The U.S. military developed a program to eliminate all tobacco use from the armed forces. e. The Surgeon General issued a report stating that smoking is a health hazard. HHH HHH CHHC C HOH HH CHH C HH HH CHOH C HHH HHH CHOHC C HOHH HHH CHCC C H H H HOHH HHH CHHC C – THE GED SCIENCE EXAM– 205 9. Paola is an engineer at an environmental con- sulting firm. Her job is to analyze air quality and the amount of toxic emissions due to highway traffic. The amount of emissions depends on the number of lanes and on the average speed of the traffic. The greater the number of lanes and the slower the cars move, the higher the amount of toxic emissions. Which of these choices corre- sponds to the highest amount of toxic emissions into the atmosphere? a. a two-lane highway at 2 A.M . on Monday b. a four-lane highway at 2 A. M. on Tuesday c. a two-lane highway at 5:30 P.M . on Wednesday d. a four-lane highway at 5:30 P.M. on Thursday e. a two-lane highway at 5:30 P.M. on Sunday 10. Many types of learning occur only at particular times called sensitive periods. (For example, chil- dren born blinded by cataracts can learn to see if the cataracts are removed by age 10. If the cataracts are removed later in life, these people can see random shapes and colors, but are unable to interpret them.) A scientist is inter- ested in knowing whether there is a sensitive period for chaffinch birds to learn to sing the species song, and if so, how long this period lasts. Which of the following experiments would be most suitable for his purpose? a. Take 20 just-hatched chaffinch birds from their environment. Bring them up in isola- tion, so that they are not exposed to their species song. Every week, return one bird to its environment and keep a record of the number of weeks it spent in isolation and whether it learned to sing. b. Take 20 just-hatched chaffinch birds from their environment. Bring them up with birds of a different species, so they are exposed to songs that do not resemble their own. Every week, return one bird to its environment and keep a record of the number of weeks it spent with birds of a different species and which song it learned to sing. c. Take 20 just-hatched chaffinch birds from their environment. Every day, play them a recording of the song of their species. Reward with food the birds that try to imitate the recorded sound, and note the number of weeks it took each one to learn to sing. d. Take 20 chaffinch birds, of any age. Every day, play a recording of the song of another bird species. Record the age of every bird that was able to learn the song of the other bird species. e. Bring up 20 just-hatched chaffinch birds among both adult chaffinch birds and adult birds of another species. Record the amount of time it took just-hatched birds to sing, and determine whether the presence of the other species improved or deterred their ability to learn to sing their species song. Pretest Answers and Explanations 1. b. Longitude is the only factor on the list that does NOT influence climate. In places on Earth that have the same longitude, noon occurs at the same time, but those places don’t necessarily have the same climate. For example, Maine and Florida are at approximately the same longitude, but the climate in Maine is much colder than Florida, because Florida is closer to the equator (latitude), choice a. Altitude can influence cli- mate, choice c. There is often snow at a top of a mountain when there isn’t any at its base. Ocean currents can also influence climate, choice d. The Gulf stream is a warm Atlantic Ocean cur- rent that provides countries in Northern Europe with a warmer climate than places at the same latitude in Canada. The presence of mountain ranges can influence climate, choice e.For example, it doesn’t rain much in Nevada’s Great Basin due to the Sierra Nevada Mountains. 2. d. Metabolic rate per gram of body weight is higher in small animals. You can infer that a large animal has the lowest metabolic rate per gram of its body weight. The largest animal on the list is the elephant. 3. c. Choice a is incorrect because the population of wolves decreased during some periods, resulting in a net decrease from 1955 to 1980. Choice b is incorrect because although the population of deer decreased during every period, the decrease was sometimes more dramatic than during other times, i.e., the rate of decrease was not constant. Choice d is incorrect because the pop- ulation of deer did not increase over time. Choice e is incorrect because the population of deer in 1975 was 120, not 45. – THE GED SCIENCE EXAM– 206 4. d. The information presented in the chart contra- dicts statements in choices a, b, and e. There is no discussion or direct evidence that can sup- port statement c. 5. b. According to the molecular structure provided in the question, 2-propanol has three carbon atoms, eight hydrogen atoms, and one oxygen atom. Only the structure in choice b has the same number of each of those atoms, but in a different arrangement (oxygen is attached to a different carbon), making the structure in choice b, an isomer of 2-propanol. 6. d. Hero and Fermat both worked to develop theo- ries to explain reflection and rectilinear propa- gation of light, phenomena they observed in nature. Choice a is incorrect: According to the text, Fermat explained both reflection and refraction with his principle of least time. Choice b is incorrect; the term rectilinear propa- gation, not reflection, means that light travels in straight lines. The statement in choice c is not supported by the passage. Although quantum mechanics had roots in the study of the propa- gation of light, which Hero pursued, there is no evidence that Hero, who lived centuries before quantum mechanics was formulated, had insight into quantum mechanics. Choice e is incorrect because Fermat rejected the shortest- path theory and showed that light travels along the path that takes the least time. 7. c. This is the only statement that is NOT supported by the passage. Both of the scientists mentioned tried to formulate theories that were based on observations and experimental evidence. 8. a. The data and information presented show a strong indication that there is a link between smoking and lung cancer. The possible effects of making these figures public are laws and social programs that aim to increase the awareness of the hazards of smoking, and limit smoking— choices b, d, and e. Another potential effect is a decrease in the number of smokers, choice c. The statement in choice a may be true, but it is not connected to the figures that show a link between smoking and cancer. 9. d. You are told that the emissions are greater when there are more lanes of traffic. Therefore, a four- lane highway results in more emissions than a two-lane highway. This eliminates choices a, c, and e. Since emissions are greater when the cars move slowly, the emissions are likely to be higher during rush hour traffic jams, choice d, than at 2:00 A. M., choice b. 10. a. The experiments described in choices b, d, and e, which involve introducing the chaffinch birds to other bird species, contain too many variables, and do not directly test what is required. Experi- ment c is faulty because the birds, although they are brought up in isolation, are exposed to the recording of the song. The effect of the lack of exposure can therefore not be tested. The fact that a reward for learning is included addition- ally complicates the experiment described in choice c, as it adds extra variables. Pretest Assessment How did you do on the science pretest? If you answered seven or more questions correctly, you have earned the equivalent of a passing score on the GED Science Test. But remember that this pretest only covers a fraction of the material you might face on the GED exam. It is not designed to give you an accurate measure of how you would do on the actual test. Rather, it is designed to help you determine where to focus your study efforts. For success on the GED, review all the chapters in this section thoroughly. Focus on the sections that correspond to the pretest questions you answered incorrectly. – THE GED SCIENCE EXAM– 207 . time. Choice e is incorrect because the population of deer in 1975 was 120, not 45 . – THE GED SCIENCE EXAM– 206 4. d. The information presented in the chart contra- dicts statements in choices