本题目来源于试卷: Interaction & Interdependence C.2 Cell Respiration，类别为 IB生物学
[单选题]
Which substance is present in the :j l65c4eh blkbrewip1k;: ,5v:bwn7fnl q bn kywf g+es(oi:+ ;mmgng of beer but not found in bread?
A. Carbon dioxide
B. Lactic acid
C. Ethanol
D. Water
参考答案: C
本题详细解析:
Both, the brewing of beer and baking of bread, involve anaerobic z f3j) f:bze2tyeast fermentation. In the brewing of beer, yeast feeds on glucose and respires anaerobically to produce ethanol, caf t3b:)f jze2zrbon dioxide and energy. The ethanol produced is the alcohol found in beer. Similarly, with the baking of bread, yeast respires anaerobically to produce ethanol, carbon dioxide and energy. However, the ethanol that is produced evaporates during baking.
Carbon dioxide (Choice A) is a product present in both the brewing of beer and the baking of bread. Carbon dioxide is soluble in beer and is found in small amounts. It is responsible for the rising of the bread.
Likewise, water (Choice D) is also a substance present in both the brewing of beer and the baking of bread. In the brewing of beer and in the baking of bread, water is added to the mixture.
In addition to yeast fermentation, anaerobic respiration can also occur in humans and other animals. This is known as lactic acid fermentation. Glucose is not broken down completely and forms lactic acid (Choice B) in the absence of oxygen.
| 
