题干

下列关于酶的叙述中,不正确的是

A:酶的水溶液具有亲水胶体性质,不能通过半透膜

B:酶能在温和条件下加快反应速率,并且具有专一性

C:酶的活性不受高温、紫外线等物理因素的影响

D:过酸、过碱会导致酶的变性,从而影响酶活力

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答案(点此获取答案解析)

C

同类题3

根据短文理解,选择正确答案。

    Each time I see a balloon, my mind flies back to a memory of when I was a six-year-old girl. It was a rainy Sunday and my father had recently died. I asked my mom if Dad had gone to heaven. "Yes, honey. Of course." she said.

    "Can we write him a letter?"

    She paused, the longest pause of my short life, and answered, "Yes."

    My heart jumped. "How? Does the mailman go there?" I asked.

    "No, but I have an idea." Mom drove to a party store and returned with a red balloon. I asked her what it was for.

    "Just wait, honey. You'll see." Mom told me to write my letter. Eagerly, I got my favorite pen, and poured out my six-year-old heart in the form of blue ink. I wrote about my day, what I learned at school, how Mom was doing, and even about what happened in a story I had read. For a few minutes it was as if Dad were still alive. I gave the letter to Mom. She read it over, and a smile crossed her face.

    She made a hole in the corner of the letter where she looped the balloon string. We went outside and she gave me the balloon. It was still raining.

    "Okay, on the count of three, let go. One, two, three."

    The balloon, carrying my letter, darted upward against the rain. We watched until it was swallowed by the mass of clouds.

    Later I realized, like the balloon, that Dad had never let his sickness get him down. He was strong. No matter what he suffered, he'd persevere, hang on, and finally transcend this cold world and his sick body. He rose into sky and became something beautiful. I watched until the balloon disappeared into the gray and white and I prayed that his strength was hereditary. I prayed to be a balloon.