Questions 3 to 5 refer to the following passage:One of the key necessities for understanding an organism’s
evolutionary history is the identification of the habitats in which
the organism’s ancestors thrived. Biologists have developed such
techniques as radiocarbon dating and biochronology to date fossils and
thereby arrive at an approximate range for an organism’s existence. But
knowing that an organism existed during a certain time period says
little about the environment that the organism inhabited. Since the
earth periodically goes through heating and cooling periods, biologists
cannot simply assume that a region’s current climate is the same as it
was for, say, a lemur that inhabited that region six million years ago.
To get past this quandary, biologists study the fossils of
foraminifera, which are microscopic organisms suspended in the
waters of the world’s oceans. Foraminifera consume two types of
oxygen isotope: oxygen-16 and oxygen-18. Oxygen-16 is lighter
than oxygen-18, and as global temperatures rise, more oxygen-16
than oxygen-18 evaporates. By studying the fossils of foraminifera,
researchers are able to identify the concentrations of these two isotopes
at a given time. Researchers can then use the different ratios of the
two isotopes during different time periods to make highly educated
inferences about the global climate during a specific time period.- In the context in which it appears, “quandary” (line 11) most nearly
means
A investigation
B dilemma
C conjecture
D approximation
E surprise - The passage is primarily concerned with
A introducing a problem and explaining a technique for addressing it
B highlighting the different ways that two types of chemicals can be
used
C evaluating the usefulness of a scientific strategy
D introducing a scientific finding and discussing its implications
E explaining a difficulty faced by scientists
5101520138 PART 2 ■ GRE ANALYTICAL WRITING AND VERBAL REASONING02-GRE-Test-2018_107-172.indd 138 13/05/17 11:06 am