Bunuel wrote:
Which of the following most logically completes the passage?
Leptin, a protein occurring naturally in the blood, appears to regulate how much fat the body carries by speeding up the metabolism and decreasing the appetite when the body has too much fat. Mice that do not naturally produce leptin have more fat than other mice, but lose fat rapidly when they are given leptin injections. Unfortunately, however, leptin cannot be used as a dietary supplement to control fat, since __________.
A. the digestive system breaks down proteins before they can enter the bloodstream
B. there are pharmaceuticals already available that can contribute to weight loss by speeding up the metabolism
C. people with unusually low levels of leptin in their blood tend to have a high percentage of body fat
D. the mice that do not naturally produce leptin were from a specially bred strain of mice
E. mice whose bodies did produce leptin also lost some of their body fat when given leptin injections
NEW question from GMAT® Official Guide 2019
(CR04159)
Question Type: Complete the Argument/Weaken
Analysis: Leptin, a naturally occuring protein, regulates accumulation of body fat by controlling hunger & metabolism. This is supported by the research on mice that do not naturally produce leptin & are injected with supplemental leptin, have shown to lose fat. The leptin in the blood stream of mice is able to carry out its function of reducing fat.
Since the conclusion starts with "Unfortunately..." we need to find a statement that will weaken, the claim of usage of leptin as a dietary supplement to lose fat.
A. the digestive system breaks down proteins before they can enter the bloodstream -
Correct. Since if leptin is broken down by the digestive system, before it reaches the blood stream, it may not be able to carry out its intended function of regulating fat loss. B. there are pharmaceuticals already available that can contribute to weight loss by speeding up the metabolism - Incorrect. Out of scope.
C. people with unusually low levels of leptin in their blood tend to have a high percentage of body fat - Incorrect. Restates an outcome of the premise of the argument.
D. the mice that do not naturally produce leptin were from a specially bred strain of mice - Incorrect. If the mice were from a special bred, we do not know whether they are resistant to leptin & had some other mechanism for loosing fat.
E. mice whose bodies did produce leptin also lost some of their body fat when given leptin injections - Incorrect. Supports the usage of leptin, since maybe they produced low levels of leptin & supplemental leptin helped them reduce their body fat.
Answer A.
Thanks,
GyM
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