题干

实验中用35S标记一定量的氨基酸,来培养某哺乳动物的乳腺细胞,测得与合成和分泌乳蛋白相关的一些细胞器上放射性强度的变化曲线如图甲所示,以及在此过程中有关的细胞结构膜面积的变化曲线如图乙所示.图中曲线所指代的细胞结构相同的是(  )

A:a和d

B:a和e

C:b和d

D:c和d

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答案(点此获取答案解析)

C

同类题3

阅读理解

    In 1971 a young man who grew up very poor was travelling across the country, trying to make a new start for himself. Along the way he had completely run out of(用光) money and was forced to spend the night in his car. This continued until one morning, after a week of sleeping in his car, he walked nervously into a restaurant and ordered a big breakfast.

    After eating his first good meal in weeks, he found himself lying to the waiter, telling him he had lost his wallet. The waiter, who was also the owner, walked behind the chair where the young man had been sitting. He bent down, and came up with a $20 bill that looked as if it had fallen on the floor and said, “Son, you must have dropped this,” the owner said. The young man couldn't believe his luck! He quickly paid for the breakfast, left a tip, bought gas with the change, and headed West.

    On the way out of town, he began to understand what the owner did. Maybe nobody dropped the money at all. “Maybe that fellow just knew I was in trouble and he helped me in a way that didn't embarrass(使尴尬) me. So I just made a promise to help other people if I can.”

    Later, he worked very hard and became a rich man. Now he lives near Kansas City. Each year he gives away thousands of dollars. He is known as the “Secret Santa” because at Christmas time each year, he personally hands money out to those on the street and at restaurants. Last year, he gave more than $50,000 away in Kansas City.