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在现行初中动物学课本中,有些教材内容,由于不是重点及照顾初中学生的接受能力,叙述较简单,如果教师忽视对教材深入细致的钻研和运用直观教学,必将影响学生对概念的正确理解。现提出几个容易发生的问题,供教师进行教学时参考: 鲫鱼的呼吸动作在鲫鱼的呼吸中,口、鳃盖、鳃孔如何配合活动?水在什么情况下由口流入?在什么情况下由鳃孔流出? 鲫鱼的呼吸动作主要靠口、鳃盖和下颌的的活动来完成。当鲫鱼的口张开时,鳃盖向外移动,略往前缩,鳃盖膜紧贴头部两侧,鳃孔关闭,同时下颌降低,口腔内容积增加,产生负压,水由外界进入口腔(图1,A)。口闭,鳃盖内收,略往后伸,下颌升高,口腔容积减少,产生正
In the existing zoological textbooks for junior high schools, some of the contents of teaching materials are relatively simple because they are not focused and take care of the acceptability of junior high school students. If teachers neglect to conduct in-depth and meticulous research on teaching materials and use visual teaching, they will certainly affect students’ correct understanding of concepts . Now put forward a few easy problems for teachers to teach reference: Crucian carp breathing in the crucian carp in the mouth, operculum, gill hole with activities? Under what circumstances the water flow from the mouth? Under what circumstances Outflow from the gill hole? Crucian carp respiratory action mainly rely on mouth, gill cover and jaw activity to complete. When the carp’s mouth open, the gill cover moves outward, slightly forward shrinkage, gill cover membrane close to both sides of the head, gill hole closed at the same time lower jaw, the oral cavity volume increases, negative pressure, water from the outside into the mouth Figure 1, A). Mouth closed, gill cover adduction, slightly stretched out after the lower jaw increased oral volume decreased to produce positive