题干

下表是探究淀粉酶对淀粉和蔗糖作用的实验设计及结果:

试管编号

2mL3%淀粉溶液

+

+

+

2mL3%蔗糖溶液

+

+

+

1mL2%的新鲜淀粉酶溶液

+

+

+

+

+

+

反应温度(℃)

40

60

80

40

60

80

2mL菲林试剂

+

+

+

+

+

+

砖红色深浅

++

+++

+

根据实验结果,以下结论不正确的是(    )

A:本实验依据的原理之一是淀粉和蔗糖水解后都能产生可溶性还原糖

B:本实验的实验变量是反应物的种类和温度

C:本实验可用碘液代替斐林试剂进行结果的检测

D:本实验中淀粉酶的活性在60℃最高

上一题 下一题 0.0难度 选择题 更新时间:2017-06-05 02:38:35

答案(点此获取答案解析)

C

同类题5

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    I'd planned to spend my weekend in the sun, potting flowers outdoors. But that was before the pair of crows (乌鸦). Out of nowhere, they had set up their base camp in our backyard.

    We first discovered our feathered enemies on Friday morning. It was early, and the sound the birds made traveled through our neighborhood. I figured they'd go away soon. But, no. They were getting louder and probably annoying my neighbors nearly as much as us with the noise. I admit I got a little desperate.

    Then, on Sunday afternoon, I looked out the kitchen window to see our dog Quatchi staring at something on the ground. I went to explore and found a small coal-black bird in the grass. Its eyes were milky, and it stayed perfectly still as my dog inched towards it. Only when Quatchi touched his nose to its head did it walk away. I took hold of the dog and locked him inside and came back with my camera.

    It never occurred to me that the young would be hanging out on the ground, growing and gaining strength as its parents guarded it from above. The second I saw this little creature I forgave the crows.

    To be honest, I've never been much of a bird person. I also have a healthy respect for birds, and by healthy I mean slightly fear-based. They're basically living dinosaurs.

    I wish they'd chosen another backyard. There are only so many sunny days in Seattle, and I still can't do any gardening out there. But I'm also grateful that I got to see this little bit of nature unfold up close. It's pretty amazing.

    The experience has also strengthened my desire to create a beautiful backyard garden that attracts lots of bees, butterflies, and yes, birds. They are welcome here.