《2026年水木金卷高考模拟试卷精编英语》

C
Tons of fruits and vegetables are produced, processed and shipped on a daily basis so we can buy them fresh. Many of these pieces of produce, however, never make it into stores. This is because many fruits and vegetables, such as apricots, mushrooms, lettuce and pears, turn brown or spoil (变质) over time.
This reaction is also called enzymatic browning and is one of the largest causes of spoilage in fruits and vegetables—even though it does not make the food harmful to eat. The name enzymatic browning comes from the fact that an enzyme (酶) within the fruit turns the fruits brown. But what exactly happens during the enzymatic browning process?
The process occurs when chemicals inside the fruit come into contact with oxygen in the air. This produces melanin (黑色素), the same dark brown pigment that colors human hair, skin and eyes. The enzyme responsible for the browning is called polyphenol oxidase (or PPO). In the presence of oxygen, the PPO enzyme changes substances known as phenolic compounds (化合物) into different compounds called quinones (醌类). The quinones then react with other compounds to form melanin. Melanin is what turns the fruits and vegetables brown.
This reaction, however, usually does not happen within fresh fruits and vegetables because the PPO and the phenolic compounds are separated in plant cells.
The enzymatic browning process is only caused when the PPO, the phenolic compounds and oxygen come in contact with each other. This is exactly what happens when a fruit is cut, falls or is knocked around too much. When fruit tissue is damaged due to heat, cold, age or mechanical stress, its cells break open and the phenolic compounds and the enzyme are released and mix with oxygen in the air. As a result, the damaged tissue turns brown almost immediately.
In the food industry, lots of attempts have been made to prevent enzymatic browning and keep produce appearing fresh for a long time. One example is the development of the Arctic apple. This apple was improved so that it no longer produces the PPO enzyme. With no enzyme present, the browning reaction cannot occur.
Another solution is to treat the produce in a specific way to inhibit the enzyme, slowing the browning reaction. Enzymes can only work in certain environments. Most cannot function if it gets too cold or too warm.
46. What do we know about enzymatic browning?
A. A process that makes food harmful to eat.
B. A chemical reaction that improves the taste of produce.
C. A method used to preserve fruits and vegetables.
D. A reaction caused by an enzyme that turns fruits and vegetables brown.
47. What is the specific role of oxygen in the enzymatic browning process?
A. It initiates the release of the PPO enzyme.
B. It reacts with melanin to form brown pigments.
C. It speeds up the change of phenolic compounds into quinones.
D. It protects plant cells from damage during transportation.
48. What could be inferred from Paragraph 5?
A. Enzymatic browning occurs only when fruit is exposed to heat.
B. Enzymatic browning can result from various forms of fruit tissue damage.
C. Enzymatic browning is prevented when fruit is stored at room temperature.
D. Enzymatic browning occurs only when fruit is knocked around too much.
49. What conclusion can we draw from the passage?
A. Enzymatic browning makes fruits and vegetables unsafe to eat.
B. The browning process cannot be stopped once it starts.
C. Enzymatic browning only occurs in fruits but not in vegetables.
D. The food industry has developed methods to reduce or prevent enzymatic browning.
50. How can the browning reaction be slowed down?
A. By treating produce to inhibit the enzyme.
B. By adding more oxygen to the environment.
C. By increasing the temperature of storage.
D. By exposing produce to sunlight.

答案： 46.D 细节理解题。题干意为:关于酶促褐变,我们知道什么?根据第二段中“This reaction is also called enzymatic browning and is one of the largest causes of spoilage in fruits and vegetables”和“The name enzymatic browning comes from the fact that an enzyme(酶)within the fruit turns the fruit brown.”可知,酶促褐变是指一种使水果和蔬菜变成棕色的酶所引起的反应。故选D。
47.C 细节理解题。题干意为:氧气在酶促褐变过程中的具体作用是什么?根据第三段中“In the presence of oxygen,the PPO enzyme changes substances known as phenolic compounds(酚类化合物)into different compounds called quinones(醌类).”可知,在氧气的作用下,PPO酶将酚类化合物转变为不同的醌类化合物。由此可知,氧气加速了酚类化合物向醌类化合物的转变。故选C。
48.B 推理判断题。题干意为:从第五段中可以推断出什么?根据第五段中“When fruit tissue is damaged due to heat,cold,age or mechanical stress,its cells break open and the phenolic compounds and the enzyme are released and mix with oxygen in the air.As a result,the damaged tissue turns brown almost immediately.”可知,当水果组织因高温、低温、自然衰老或机械损伤而受损时,其细胞会破裂,释放出内部的酚类化合物和酶,这些成分与空气中的氧气接触后发生反应,导致受损组织几乎瞬间变为褐色。由此可推知,酶促褐变可由各种形式的水果组织损伤引起。故选B。
49.D 细节理解题。题干意为:我们可以从食品行业中得出什么结论?根据倒数第二段内容可知,在食品行业中,人们尝试阻止酶促褐变,例如北极苹果的研发,这种品种的苹果不再产生PPO酶,从而就不会发生褐变反应;根据最后一段中“Another solution is to treat the produce in a specific way to inhibit the enzyme,slowing the browning reaction.”可知,另一种解决办法是用一种特殊的方法来处理农产品,以抑制酶的作用,从而减缓褐变反应。由此可知,食品行业已经研发出减少或防止酶促褐变的方法。故选D。
50.A 细节理解题。题干意为:怎样能减缓褐变反应?根据最后一段中“Another solution is to treat the produce in a specific way to inhibit the enzyme,slowing the browning reaction.”可知,用一种特殊的方法来处理农产品以抑制酶的作用可以减缓褐变反应。故选A。