问题 实验题

已知2H2O2=2H2O+O2↑,可以通过观察反应过程中O2的生成速度(即气泡从溶液中释放的速度)来判断H2O:分解反应的速度。请用所给的实验材料和用具设计实验,使其能同时验证过氧化氢酶具有催化作用和高效性。要求写出实验步骤,预测实验结果,得出结论,并回答问题。

实验材料与用具:适宜浓度的H2O2溶液,蒸馏水,3.5%FeCl3溶液,0.01%牛过氧化氢酶溶液,恒温水浴锅,试管。

(1)实验步骤:__________________________________。

(2)实验结果预测及结论:

整个实验中不同处理的试管中O2的释放速度从快到慢依次是________________。由此可得出的结论是__________________。

(3)如果仅将实验中的恒温水浴改为80℃,重做上述实验,O2释放的速度最快的是_______________,原因是________________________。

答案

(1)①.取3支试管,各加入等量且适量的H2O2溶液,放入37℃恒温水浴锅中保温适当时间;

②.分别向上述3支试管中加入等量且适量的蒸馏水、FeCl3溶液和过氧化氢酶溶液;

③.观察各管中气泡产生的快慢

(2)加酶溶液的试管、加FeCl3溶液的试管、加蒸馏水的试管   酶具有催化作用和高效性

(3)加FeCl3溶液的试管   在此温度下,FeCl3催化作用加快,而过氧化氢酶因高温变性而失去了活性

阅读理解

Home to me means a sense of familiarity and nostalgia(怀旧). It's fun to come home. It looks the same. It smells the same. You'll realize what's changed is you. Home is where we can remember pain, live, and some other experiences; We parted here; My parents met here; I won three championships here.

If I close my eyes, I can still have a clear picture in mind of my first home. I walk in the door and see a brown sofa surrounding a low glass-top wooden table. To the right of the living room is my first bedroom. It's empty, but it's where my earliest memories are.

There is the dining room table where I celebrated birthdays, and where I cried on Halloween-when I didn't want to wear the skirt my mother made for me. I always liked standing on that table because it made me feel tall and strong. If I sit at this table, I can see my favorite room in the house, my parents' room. It is simple: a brown wooden dresser lines the right side of the wall next to a television and a couple of photos of my grandparents on each side. Their bed is my safe zone. I can jump on it anytime - waking up my parents if I am scared or if I have an important announcement that cannot wait until the morning.

I'm lucky because I know my first home still exists. It exists in my mind and heart, on a physical property (住宅) on West 64th street on the western edge of Los Angeles. It is proof I lived, I grew and I learned.

Sometimes when I feel lost, I lie down and shut my eyes, and I go home. I know it's where I'll find my family, my dogs, and my belongings. I purposely leave the window open at night because I know I'll be blamed by Mom. But I don't mind, because I want to hear her say my name, which reminds me I'm home.

小题1:Why does the author call her parents' bed her "safe zone"(Paragraph 3)?

A.It is her favorite place to play.

B.Her needs can be satisfied there.

C.Her grandparents' photos are lined on each side.

D.Her parents always play together with her there.小题2:What can be learned from the passage?

A.The old furniture is still in the author's fist bedroom.

B.The author can still visit her first physical home in Los Angeles.

C.The author's favorite room in her first home is the dining room.

D.Many people of the author's age can still find their first physical homes.小题3:Sometimes when she feels lost, the author will _______.

A.Open the window at night

B.lie down in bed to have a dream

C.try to bring back a sense of home

D.go to Los Angeles to visit her mom小题4:What is the author's purpose of writing this passage?

A.To express how much she is attached to her home.

B.To declare how much she loves her first house.

C.To describe the state of her family.

D.To look back on her childhood.

单项选择题