题目

If you take it for granted that to study in university is the same as at middle school and high school，then you will be in for a surprise. A change of attitude is involved in many ways when you go up to university.Although the process has been going on since you went to middle school，the biggest change is going to take place.Now，instead of taking several subjects，you have chosen one major subject because you find it interesting and worth exploring further.The choice is yours.You also have before you the goal of getting a degree.The degree，and the stages you have to pass throug18．图甲为植物叶肉细胞中发生的某一生理过程，图乙为该细胞在不同条件下的光合速率变化曲线，请据图分析回答：（1）图甲中的A代表叶绿体中的色素（光合色素），分离A依据的原理是其在层析液中的溶解度不同．（2）图乙中t1之前，叶肉细胞中能够产生[H]的具体场所有细胞质基质和线粒体基质．（3）图乙种t2突然给予光照后，科学家发现在最初的一段时间内叶绿体中的光合产物并没有显著增加，说明被还原的C3主要用于五碳化合物（C5）的合成，从而加快卡尔文循环/暗反应的进行．（4）t2-t3时间段中，继续增加光照强度光合速率会不变（填“增强”、“减弱”或“不变”），在t4时突然停止光照，叶肉细胞O2的释放速率迅速下降，而C3的还原却依然可以维持一段时间，原因是光反应积累的[H]和ATP可以继续维持暗反应的进行．