题干

下列有关构成细胞的元素和化合物的叙述,正确的是(    )

A:组成淀粉和糖原的化学元素主要是C,H,O

B:固醇是细胞内良好的储能物质

C:种子储存前,晒干是为了减少自由水的含量,降低种子的代谢速率

D:磷脂是细胞膜的主要成分,也是线粒体、中心体和叶绿体等生物膜的主要成分

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答案(点此获取答案解析)

C

同类题2

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    John and Mary had a nice home and two lovely children. John had just been asked to go on a business trip to another city for several days and Mary would go with him too. They hired a reliable woman to care for their children and returned home a little earlier than they had planned.
    As they drove into their hometown, they found a home on fire. After having a look, Mary said, “Oh well, it isn't our fire. Let's go home.” But John drove closer and said, “That home belongs to Fred Jones who wouldn't be off work yet. Maybe there is something we could do.”
    John noticed an old lady screamed to him, “A children! Get the children!” John grabbed (抓住) her by the shoulder saying, “Get a hold of yourself and tell us where the children are!” “In the basement,” cried the lady.
    In spite of Mary's disagreement, John soaked (浸湿) his clothes and ran to the basement which was full of smoke. He found the door and grabbed two children. As he left he could hear some more cry. He sent the two badly frightened children into the waiting room and asked how many more children were down there. The told him two more and Mary grabbed his arm and screamed, “John! Don't go back! It's dangerous! That house will fall down in any second!”
    But he shook her off and went back. It seemed a very long time before he found both children and started back. As he climbed up the endless steps the thought went through his mind that there was something strangely familiar about the little bodies next to him, and at last when they came out into the sunlight and fresh air, he found that he had just rescued his own children. The baby-sitter had left them at this home while she did some shopping.