1.简单
A solution has a pH of 3. How is it described?
- ANeutral
- BBasic
- CAcidic
- DIsotonic
2.简单
What is the main job of the cell wall in a plant cell?
- ATo make proteins for the cell
- BTo control which genes are switched on in the nucleus
- CTo release energy from glucose
- DTo support the cell and stop it from bursting
3.简单
Which enzyme adds new nucleotides to build a new DNA strand?
- APepsin
- BHelicase
- CDNA polymerase
- DRNA polymerase
4.中等
In a eukaryotic cell, where does transcription take place?
- AOn ribosomes in the cytoplasm
- BIn the Golgi apparatus
- CIn the nucleus
- DIn the lysosomes
5.中等
What does RNA polymerase do?
- AIt removes introns from pre-mRNA
- BIt builds an RNA strand from a DNA template
- CIt builds a protein from an mRNA template
- DIt copies the whole genome before cell division
6.中等
DNA 模板链的序列是 T-A-C。与之匹配的 mRNA 密码子是什么?
- AA-U-G
- BA-T-G
- CU-T-G
- DT-A-C
7.困难
一种形状与底物相似的分子结合到酶的活性位点上,使反应变慢。如何减弱它的影响?
- A把反应中的水全部去除
- B加入多得多的底物
- C降低底物的量
- D加入更多的抑制剂
8.困难
为什么每种酶通常只作用于一种底物?
- A底物是由酶自己制造的
- B酶只能在细胞核内起作用
- C其活性位点的形状只与该底物契合
- D每种酶都含有其底物的 DNA
答案
- 1. C · Acidic
- 2. D · To support the cell and stop it from bursting
- 3. C · DNA polymerase
- 4. C · In the nucleus
- 5. B · It builds an RNA strand from a DNA template
- 6. A · A-U-G
- 7. B · 加入多得多的底物
- 8. C · 其活性位点的形状只与该底物契合
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