题干

下面是某蛋白质的肽链结构示意图(图1,其中数字为氨基酸序号)及部分肽链放大图(图2),下列叙述中正确的是()

A:该蛋白质中含有1条肽链124个肽键

B:图2中含有的R基是①②④⑥⑧

C:从图2推知该肽链只含有2个游离的羧基

D:从图2推知该肽链至少含有2个游离的氨基

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答案(点此获取答案解析)

D

同类题2

完形填空。阅读下面短文,从短文后各题所给的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

    Virak Mao moved from Cambodia six and a half years ago. He was an exciting and 1 12-year-old boy,looking forward to his new life in Canada but fearful he wouldn't make friends, 2 since he didn't speak English. What great progress he has 3 since then.

    First of all, he got over those early difficulties and 4 friends. Mao not only mastered 5 but won the Grade 9 French award. At school, he 6 to organize school events. Mao also 7 at school, such as cleaning the library and helping others . Mao had wanted to be an engineer 8 after struggling with chemistry, he discovered a new passion for 9. At his Buddhist temple, Mao is a leader and 10 those who came to Canada for the first time to work hard. He also 11 in cultural dancing with other temple members, donating any 12 they raise back to the temple to buy supplies for the poor. Since the summer of 2011, he has held a job at a clothing store to help 13 his family. In June, Mao 14 from C.W. Jefferys and is now in the business management program at Ryerson University.

    He is also the first winner of a new scholarship 15 by the Graduate Business Council with the purpose of helping a student, 16 wants to improve his community and in 17 of money. Awarded the scholarship in June, Mao spoke about the 18 of the award. “I was so excited. It was a huge relief for me,” he said, adding he would buy textbooks and school supplies with the award. “I am really 19 they raised this money to award me the scholarship. I just have no words. Anyone who works hard gets well 20.”