Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened...
GMAT Critical Reasoning : (CR) Questions
Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally. The Egyptians, however, did not discover leavened bread until about 3000 B. C. That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.
Which of the following, if true, provides the strongest evidence that the two developments were causally related?
Passage Analysis:
| Text from Passage | Analysis |
| Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally. |
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| The Egyptians, however, did not discover leavened bread until about 3000 B.C. |
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| That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain. |
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Argument Flow:
The passage sets up a historical puzzle and then hints at a possible solution. First, we learn that yeast was everywhere and Egyptians must have accidentally mixed it into their bread for centuries, yet they didn't discover leavened bread until 3000 B.C. Then we're told that around this same time, a new wheat variety was introduced that didn't require toasting.
Main Conclusion:
There's no explicit conclusion in this passage - it's setting up information for us to evaluate whether the timing coincidence between leavened bread discovery and the new wheat variety suggests a causal relationship.
Logical Structure:
The passage presents a puzzle (why did leavened bread discovery take so long despite widespread yeast?) and then gives us a potential key piece (new wheat variety at the same time). The logical structure suggests that something about this new wheat variety might have made leavened bread discovery possible, but we need to figure out what that connection could be.
Prethinking:
Question type:
Strengthen - We need to find evidence that makes the causal connection between the new wheat variety and the discovery of leavened bread more believable
Precision of Claims
The argument presents a timing coincidence (both developments around 3000 B.C.) and suggests they might be causally related. We need to strengthen this potential causal relationship with specific evidence about how the new wheat processing method enabled leavened bread discovery
Strategy
Since we have a timing coincidence that hints at causation, we need to find evidence that explains HOW the new wheat variety actually enabled or facilitated the discovery of leavened bread. The key insight is that the old wheat required toasting, while the new wheat didn't. We should think about how this processing difference could have created conditions that finally allowed the Egyptians to notice yeast's leavening effects, despite centuries of accidental yeast contact
This tells us that unleavened bread continued to be consumed even after leavened bread was discovered. This doesn't help establish a causal connection between the new wheat variety and the discovery of leavened bread - it's just about consumption patterns after the discovery had already happened. This doesn't strengthen the causal relationship we're looking for.
This suggests that grain-toasting pits became available for baking when Egyptians stopped toasting the new wheat variety. While this might have provided new baking infrastructure, it doesn't explain why the discovery of leavened bread was impossible before this wheat variety arrived. We need to understand what specifically prevented leavening with the old wheat processing methods.
This provides the crucial mechanistic explanation we need. It tells us that heating wheat kernels destroys gluten, and gluten must be present for yeast to leaven bread dough. This perfectly explains our puzzle: with old wheat varieties that required toasting, the gluten was destroyed, making leavening impossible despite centuries of accidental yeast contact. The new wheat variety that didn't need toasting preserved the gluten, finally enabling yeast to work. This creates a clear causal pathway linking the wheat processing change to the leavening discovery.
This discusses the social status and consumption patterns of the new wheat variety, mentioning it was reserved for high officials. However, this doesn't explain any technical or processing difference that would enable the discovery of leavened bread. Social factors don't address the scientific puzzle of why leavening became possible.
This explains that the new wheat variety made flour production easier because the husk was more easily removed. While this might have increased wheat usage, it doesn't explain what specifically enabled the discovery of leavened bread or why previous accidental yeast contact never worked.