It is early in the morning, about seven o'clock. Peter is on the bus. He's going to school. There are many people on the bus and it is a bit hot. Peter is sitting by a window with a book in his hands. The bus driver is driving slowly(慢地). Most people on the bus are using their mobile phones. A girl in a red sweater is standing near Peter. She looks very happy. She is reading some funny things on her mobile phone. A fat boy behind him is busy playing games on  his mobile phone. A tall man is Jack. He is listening to music on the mobile phone. He’s about thirty years old. They are all busy and happy.

酵母菌是一种单细胞真菌，酿酒和做面包都需要酵母菌，它也是常用的实验材料．根据所学知识回答：

（1）利用酵母菌制作果酒的反应式为____ ．果汁发酵后是否有酒精产生，可用____ 来检验．

（2）在探究酵母菌种群数量动态变化实验中，每隔24小时取一定量的酵母菌培养液，用血球计数板进行计数，并以多次计数的平均值估算酵母菌种群密度，这种方法称为____ 法．计数之前将试管轻轻震荡几次，目的是____ ．血球计数板的计数室长和宽各为1mm，深度为0.1mm，其中25×16型的计数室有25个中方格，每个中方格又分成16个小方格．如图表示其中一个中方格的情况，该中方格中的酵母菌计数的结果是____ 个．如果计数的几个中方格中的细胞平均数为20个，则1mL培养液中酵母菌的总数为____ 个．（注：1mm³=10^﹣3mL）

（3）在探究酵母菌种群数量动态变化实验中，为了使实验数据更加准确，需要严格控制实验中的____ 等无关变量．同一温度条件下，若提高培养液中酵母菌起始种群数量，则该组别中酵母菌到达K值的时间将____ （选填增加、减少、保持不变）；若其他条件保持不变，适当提高培养液的浓度，则该组别的K值将____ （选填增加、减少、保持不变）．

实验一：如图1是同学们做粗盐提纯实验的操作示意图．

请回答下列问题：