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  3. Here’s a question about chickens and eggs you may not have heard before: How is it that an egg can be so hard to break from the

Here’s a question about chickens and eggs you may not have heard before: How is it that an egg can be so hard to break from the

admin2022-07-26  35
问题     Here’s a question about chickens and eggs you may not have heard before: How is it that an egg can be so hard to break from the outside, yet so easy for a weak little chick to peck through from the inside?
    It’s a tough question to crack. Eggshells are thought to change as the chick grows inside. As the creature develops, parts of the inner eggshell dissolve and the fuzzy little bird incorporates some of that calcium into its bones. But it remained unclear how this process influenced eggshell microstructure. Now, As Nicola Davis at The Guardian reports, a new study in Science Advances suggests that it’s all about the structure of the egg and how it develops with the growing creature inside.
    To solve the mystery and study egg structures, researchers at McGill University used a new method that allowed them to cut extremely thin sections of shell. They then analyzed these thin sections using a microscope to study shell structure.
    The team examined the shell of fertilized (受精的) eggs and compared that to unfertilized eggs. As Laurel Hamers at ScienceNews reports, they discovered that the key to the eggs’ toughness appeared to be the formation of microstructures, guided into place by proteins. They focused their analysis on one particular protein, which is found throughout the shell and is believed to be vital in the organization of mineral structure.
    As Davis explains, the special protein seems to act as a "scaffold (脚手架)" that guides the structure and density of minerals in the shell, in particular calcium. In a developed egg, the minerals in the outer layer of the shell are densely packed and rich with such special protein. But inner egg layers have a different structure, which has less of such special protein and lower density of mineral packing.
    In non-incubated eggs, the nanostructure didn’t change. But in the fertilized eggs, the structure of the inner egg appeared to shift over time. Calcium was transferred to the chicks and the inside of the shell grew weaker, making it easier for the chick to crack through. The inner shell also became bumpier (更崎岖不平的), which the researchers believe provides more surface area for chemical reactions that release calcium to the chicks.
    Knowing the structure of the egg could lead to new types of materials, says Lara Estroff, a Cornell engineer who was not involved in the study, Hamers reports. The researchers think it could even improve food safety for eggs. About 10 to 20 percent of chicken eggs crack in transport, which could lead to contamination. Understanding why some eggs are stronger than others could help breed chickens with tougher eggs.
What seems to play the most important role in making eggshells tough?
选项 A、The minerals found in the eggshells.
B、Metal elements the eggshell contains.
C、Elements that make up the eggshells.
D、A special protein in the eggshells.
答案D
解析 根据题干中的信息词making eggshells tough，可以把答题线索定位到第四段。第四段开头提到，该团队研究了受精鸡蛋的蛋壳，并将其与未受精的鸡蛋进行了对比，而接下来作者指出，据《科学新闻》的劳雷尔.汉默斯报道，他们发现鸡蛋坚韧度的关键似乎在于微观结构的构成，这是在蛋白质的引导下实现的。最后，作者进一步指出，他们的分析集中在一种特定的蛋白质上，这种蛋白质在整个蛋壳中都有发现，并且被认为在矿物结构的组织中是至关重要的。也就是说，这种特殊蛋白质决定了鸡蛋蛋壳的微观结构的构成，而蛋壳的微观结构构成似乎是鸡蛋的坚韧度的关键所在，由此可知，鸡蛋蛋壳中的特殊蛋白质对于蛋壳的坚韧度似乎起着至关重要的作用，故本题应选D。
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