英语听力文摘 光呼吸作用之谜
The Mystery of Photorespiration
光呼吸作用之谜
光呼吸作用-Photorespiration是所有行光合作用的细胞(该处“细胞”包括原核生物和真核生物，但并非所有这些细胞都能运行完整的光呼吸)在光照和高氧低二氧化碳情况下发生的一个生化过程。它是光合作用一个损耗能量的副反应。过程中氧气被消耗，并且会生成二氧化碳光呼吸作用ht约抵消30%的光合作用。因此降低光呼吸被认为是提高光合作用效能的途径之一。但是人们后来发现，光呼吸作用有着很重要的细胞保护作用。
Today, we’re talking about plants and the mystery of photorespiration, which is actually diametrically opposed to photosynthesis.
It is the process by which plants use light to convert carbon dioxide and water into the sugars that fuel the plant，right?
Right，Well, during photorespiration plants use light energy to consume oxygen and release carbon dioxide and water.
So photorespiration undoes the work of photosynthesis?
At least part of it，so under present atmospheric conditions, plants lose about twenty-five percent of the energy that they capture through photosynthesis to photorespiration.
One hypothesis is that photorespiration had a role in early evolution, when there was more carbon dioxide in the air. Another explanation is that plants use photorespiration to slow down photosynthesis under certain stressful conditions, like intense light, so that the photosynthetic apparatus doesn’t get damaged.
Given all the mystery surrounding this process, some scientists even began working on genetically engineering crop plants to minimize photorespiration. But one study suggests that photorespiration is actually important to plants after all.
Researchers at UC Davis showed that photorespiration enables a plant to convert inorganic nitrogen into a form of nitrate that’s needed for plant growth. This helps explain why plants have trouble growing in conditions with low oxygen and high carbon dioxide, which inhibit photorespiration.
Notes
1.convert v
改变(某事物)的形式或用途:
Britain converted to a decimal currency system in 1971. 英国於1971年改行十进制货币体系.
a ferry that was converted to carry troops during the war 战争期间改作运兵船的渡轮
The room was converted from a kitchen to a lavatory. 这房间由厨房改成了厕所.
~ into/to sth: be able to be changed from one form or use to another 可改变形式或用途:
a sofa that converts (in) to a bed 可改为床铺的沙发.
2.minimize, minimise v
使(某事物)减至最小量或最低程度:
To minimize the risk of burglary, install a good alarm system. 安装可靠的报警设备以减低被盗的风险.
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