单选题 Scraps of food could soon be helping power your home, thanks to an ultra-cheap bacteria-driven battery. Its developers hope that instead of feeding the dog or making garden compost(混合肥料) ,organic household waste could top up your home's electricity.
Although such "microbial fuel cells" (MFCs)have been developed in the past, they have always proved extremely inefficient and expensive. Now Chris Melhuish and technologists at the University of the West of England(UWE)in Bristol have come up with a simplified MFC that costs as little as ￡10 to make.
Right now, their fuel cell runs only on sugar cubes, since these produce almost no waste when broken down, but they aim to move on to carrot power. "It has to be able to use raw materials, rather than giving it a refined fuel," says Melhuish.
Inside the Walkman-sized battery, a colony of E. coil bacteria produce enzymes that break down carbohydrates, releasing hydrogen atoms. The cell also contains chemicals that drive a series of redox, or reduction and oxidation reactions, stripping electrons from the hydrogen atoms and delivering them steadily to the fuel cell's anode(正极). This creates a voltage that can be used to power a circuit.
To prove the MFC works, the researchers are using it to power a small light-sensitive robot. And when a number of the cells are connected in series, they could power domestic appliances, running a 40-watt bulb for eight hours on about 50 grams of sugar.
Earlier MFCs were inefficient because they relied on energy-hungry filters and pumps. By experimenting with different anode materials, the UWE team have figured out how to make their system work: they dump the bacteria and redox chemicals directly into the cell.
In its current form, the UWE team says its organic battery can produce eight times as much power as any previous MFC. But Melhuish wants to improve this, both by scaling it up and finding a better mix of redox chemicals.

单选题 Which of the following would be the most appropriate title for the passage?
【正确答案】 B
【答案解析】本题是主旨大意题。综合各段的主题句可以看出本文主要是介绍一种成本低、效率高的新型MFC。
单选题 Chris Melhuish and technologists are trying to use household wastes to ______.
【正确答案】 C
【答案解析】见第2段第2句话中的a simplified MFC that costs as little as ￡10 to make。
单选题 The word "redox” in paragraph 4 most probably means ______.
【正确答案】 A
【答案解析】本题是词义题。首先在文中找到该词所在的句子(第4段第2句)，然后细读该句，答案应该就在该句中。本题在redox一词后出现了对该词的解释or reduction and oxidation reactions(亦即氧化还原反应)。
单选题 Earlier MFCs were inefficient because they ______.
【正确答案】 C
【答案解析】本题是具体细节题。答案可以在第6段第1句话because they relied on energy-hungry filters and pumps中找到。
单选题 According to Melhuish, his present MFC ______.
【正确答案】 D
【答案解析】在最后一段中有这样一句话the UWE team says its organic battery can produce eight times as much power as any previous MFC(UWE团体说他们的有机电池与从前的MFC电池相比产生的能量要高8倍)，这说明这种型号的MFC效率已经很高了。
单选题 Which of the following statement is NOT TURE according to the passage?
【正确答案】 D
【答案解析】在第二段开始提到，“Although such‘microbial fuel cells’(MFCs) have been developed in the past，they have always proved extremely inefficient and expensive．”虽然微生物能源电池早在过去已经得到发展，但是却被证明是非常无效及昂贵的。从这句可知，A，B是正确的。而在后面提到，“when a number of the cells are connected in series，they could power domestic appliances”所以C也正确。D选项应该是“organic battery can produce eight times as much power as any previous MFC”有机电池产生的能量是过去微生物电池的八倍，所以D不正确。