以测定的CO2吸收量与释放量为指标，研究温度对某绿色植物光合作用与呼吸作用的影响．结果如图所示。下列分析正确的是( )。
- A.光照相同时间，35℃时光合作用制造的有机物的量与30℃相等
- B.光照相同时间，在20℃条件下植物积累的有机物的量最多
- C.温度高于25℃时，光合作用制造的有机物的量开始减少
- D.两曲线的交点表示光合作用制造的与呼吸作用消耗的有机物的量相等
正确答案及解析
正确答案
解析
光照相同时间，35℃时光合作用吸收CO2为3．5+3=6．5(mg／h)，30℃时吸收量为3+3．5=6．5(mg／h，因此这两个温度时的实际光合速率相等，故制造的有机物的量是相同的，A项正确。25℃时净光合速率最高，此时积累的有机物最多，B项错误。温度高于25℃时，净光合速率下降，实际光合速率没有下降，C项错误。两曲线的交点表示净光合速率=呼吸速率，这时实际光合速率是呼吸速率的2倍，故D项错误。
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