植物细胞渗透作用的解析

植物细胞渗透作用相关问题是高中生物学教学中的难点之一。本文从渗透作用模型、水分子的跨膜运输方式、植物细胞吸水、植物细胞失水、调节渗透作用的机制等方面,由浅入深地对植物细胞渗透作用进行分析,同时对植物细胞渗透作用中的一些疑难问题进行解释。

Transport Process of Isopropanol Aqueous Solution by Pervaporation

To study the transport process of isopropanol aqueous solution by pervaporation, the transport model of isopropanol and that of water at 323 K in polyvinyl alcohol(PVA) membrane were obtained in this paper. Theoretical predictions agreed well with the experimental results. The interactional parameter between water and PVA membrane is less than that between isopropanol and PVA membrane, which shows that water is preferentially dissolved in PVA membrane. The plasticizing coefficient and diffusion coefficient at infinite dilution of water are larger than those of isopropanol, which shows that the dissolution and permeation in PVA membrane of water are greater than those of isopropanol. Both the interactional parameter between water and isopropanol in the membrane and that in feed rise with the increase of isopropanol content in feed, which shows that the larger isopropanol content is, the higher selectivity of the membrane is and the more remarkable separation effect of pervaporation is.

基于科学探究的教学实践——以“水分的跨膜运输”一节为例

从学生的认知和逻辑出发,对教材资源进行了整合,并对重、难点进行了精心的设计,通过构建渗透作用模型,并应用其进行水稻细胞吸水和失水的探究活动,提升学生的科学探究、科学思维等生物学学科核心素养。