1.简单
What does homozygous mean?
- AHaving two identical alleles for a gene
- BHaving only one copy of a gene
- CHaving two different alleles for a gene
- DHaving an extra chromosome
2.简单
DNA 分子是什么形状?
- A三螺旋
- B单条直链
- C双螺旋
- D平面环
3.简单
被认为有生命的最小单位是什么?
- A分子
- B细胞
- C组织
- D原子
4.中等
What happens during telophase of mitosis?
- AThe chromosomes line up across the middle of the cell
- BA nuclear envelope forms around each set of chromosomes
- CThe sister chromatids are pulled apart
- DThe DNA is copied for the next division
5.中等
下列哪项描述的是主动运输?
- A它消耗能量,使物质逆浓度梯度移动
- B它只发生在死细胞中
- C它只使水穿过膜
- D它不消耗任何能量,使物质顺浓度梯度移动
6.中等
Why do many plants close their stomata on hot, dry days?
- ATo speed up photosynthesis
- BTo release more oxygen
- CTo take in more carbon dioxide
- DTo reduce water loss
7.困难
在基因起始部位附近插入了一个多余的碱基。为什么这通常会对蛋白质产生很大的影响?
- A它使该基因变成另一条染色体
- B它没有影响,因为密码子具有简并性
- C它只改变蛋白质中的一个氨基酸
- D它使其后所有密码子的阅读框发生移位
8.困难
Why are mutations in mitochondrial DNA passed on only from mothers to their children?
- AMitochondrial DNA is on the X chromosome
- BThe zygote's mitochondria come from the egg
- CSperm cells contain no DNA at all
- DOnly women have mitochondria in their cells
答案
- 1. A · Having two identical alleles for a gene
- 2. C · 双螺旋
- 3. B · 细胞
- 4. B · A nuclear envelope forms around each set of chromosomes
- 5. A · 它消耗能量,使物质逆浓度梯度移动
- 6. D · To reduce water loss
- 7. D · 它使其后所有密码子的阅读框发生移位
- 8. B · The zygote's mitochondria come from the egg
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