TOEFL question makers love the Clark Kent = Superman trick. Superman is Clark, Clark is Superman—same guy, different name. If you don’t recognize that, you’ll miss the answer. Don’t be like Lois Lane! Be like the girl in The Green Hornet—she spotted her boyfriend even in disguise.
These are the three questions we’ll work on.
Question 1
According to paragraph 1, in setting up his experiment, Miller assumed each of the following to be true—EXCEPT.
A. Earth’s early atmosphere probably included hydrogen and ammonia.
B. Lightning probably occurred on early Earth.
C. Electrical discharges took place deep below early Earth's surface.
D. Water was present
Question 2:
"According to paragraph 2, which of the following could have made it possible for oceans on early Earth to be hotter than 100°C?"
A. The absence of any established life-forms
B. The heat added to the water by molten lavas
C. High pressure within the atmosphere
D. The composition of the ocean water
Question 3:
"Select the TWO answer choices that, according to paragraph 2, describe effects that would have resulted from the impacts of meteorites on early Earth. To receive credit, you must select TWO answers."
A. Materials beneath the surface became molten.
B. Seas and oceans became larger.
C. Heat was added to Earth's surface.
D. Volcanic gases were added to the atmosphere.
These are the passages the questions are based on. Try to solve them yourself, and then watch the video to see how to improve your answering strategy and speed.
Paragraph 1
In the 1920s, Aleksandr Oparin, a Russian biochemist, proposed and developed the idea that life originated in the warm, watery environment of early Earth' s surface, under an atmosphere mostly composed of methane. The early seas were believed by Oparin to be rich in simple organic molecules, which reacted to form more complex molecules, eventually leading to proteins and life. Then, almost 30 years after Oparin published his ideas, Stanley Miller demonstrated that amino acids, the building blocks of the proteins necessary for life, could form under conditions thought to prevail on early Earth. Miller's experiment was elegant. He passed electric discharges through a mixture of methane, hydrogen, ammonia, and steam, and when he analyzed the results, found that he had made amino acids. The discharges were a proxy for lightning, and the gas mixture led to an educated guess about what the early atmosphere may have been like. Amino acids cannot replicate themselves, and are not themselves alive. Nevertheless, this experiment has long been recognized as a landmark for understanding a process that must have been one of the important steps in the evolution of life on Earth, the natural synthesis of amino acids. However, it now seems likely that Miller' s experiments may not be directly applicable to the events of the early Archean (that is, early in the geologic eon that lasted from Earth' s formation until about 2.5 billion years ago).
Paragraph 2
One of the problems hindering understanding of the origin of life is that environmental conditions on early Earth are not known with any certainty. It is possible to make only reasoned estimates. For example, for some fairly long period of time after formation, perhaps as much as several hundred million years, the surface must have been much hotter than it is today. Continued impacts of meteorites, large and small, would have added further heat energy, and in the earliest part of Earth history the larger impacting bodies may have broken through the cooling crust to expose underlying molten material Large quantities of volcanic gases would have been released into the atmosphere as lavas erupted onto the surface, producing a greenhouse effect far more severe than anything likely to result from human activity. It is quite possible that the early atmosphere was many times as dense as today' s, and that the seas and oceans were hot. Some have even suggested that because of the high atmospheric pressure, the oceans could have been hotter than the boiling point of water today However, life as we know it is quite sensitive to temperature, and no modern organisms are known to survive much above 100°C It is unlikely that life became established until surface temperatures had decreased to this level, or lower.