护理入学考试生物练习卷（附答案）

真核细胞的大部分 DNA 位于哪里？

1. A溶酶体中
2. B细胞膜中
3. C细胞壁中
4. D细胞核中

DNA 中含有哪四种碱基？

1. A腺嘌呤、胸腺嘧啶、鸟嘌呤和胞嘧啶
2. B腺嘌呤、尿嘧啶、鸟嘌呤和胞嘧啶
3. C腺嘌呤、胸腺嘧啶、葡萄糖和胞嘧啶
4. D丙氨酸、胸腺嘧啶、甘氨酸和半胱氨酸

What is a genetically modified organism (GMO)?

1. AAn organism that has caught a virus
2. BAn organism whose DNA has been changed by genetic engineering
3. CAn organism produced by normal sexual reproduction between two parents
4. DAn organism that has been grown in a greenhouse

How can bacteria pass antibiotic-resistance genes directly to other bacteria?

1. ABy osmosis, moving genes in water
2. BBy mitosis, sharing copies of their chromosomes with neighbours
3. CBy meiosis, forming gametes with new alleles
4. DBy conjugation, transferring plasmids through a pilus

A student's hypothesis is "Salt water slows the growth of bean seedlings." Which is a prediction based on it?

1. ASeedlings given plain water will die within a week
2. BBean seedlings need sunlight and water to grow well
3. CSalt water is made of sodium chloride and water
4. DSeedlings given salt water will grow less than those given plain water

Why are G–C base pairs held together more strongly than A–T pairs?

1. AG–C pairs form three hydrogen bonds, and A–T pairs form two
2. BG and C are both purines, so they fit more tightly
3. CA–T pairs are found only in RNA
4. DG–C pairs are joined by strong covalent bonds instead of hydrogen bonds

Griffith injected mice with heat-killed harmful bacteria mixed with live harmless bacteria. The mice died, and live harmful bacteria were found in them. What did this show?

1. AHeat makes harmless bacteria become harmful when they are injected
2. BBacteria can be killed by the immune system of mice
3. CThe mice were killed by the dead bacteria alone
4. DA substance from the dead bacteria changed the harmless ones

为什么每种酶通常只作用于一种底物？

1. A酶只能在细胞核内起作用
2. B每种酶都含有其底物的 DNA
3. C其活性位点的形状只与该底物契合
4. D底物是由酶自己制造的