1. Physical model: intuitively express the characteristics of cognitive objects in the form of objects or pictures. There are the following two categories:
(1) Natural models will use animals instead of people in biological research, and animals or plants can be selected from the natural environment to explain the structure or characteristics of the research object in biology class. For example, the structure of cells includes cell membrane, cytoplasm and nucleus. The image of peach can be used to illustrate its structural distribution. The pericarp is the outermost cell membrane, the pulp represents the cytoplasm, and the stone is similar to the nucleus, including the nuclear membrane and nucleoli. There are many junior high schools, which can be tapped.
(2) Artificial models are imitations made by professionals, teachers or students with reference to physical objects. Enlarge or reduce the physical object, but truly reflect the characteristics of the research object or simulate the expression of life process. For example, the model of DNA double helix structure made by Watson and Crick. In addition to the three-dimensional physical model, it is also a physical model that represents the research object with simplified graphics on the plane, which intuitively reflects the overall characteristics and movement history of various specific objects. For example: animal and plant cell pattern diagram, bacterial structure pattern diagram, secretory protein synthesis and transportation diagram, etc.
2. Conceptual model: through the analysis of a large number of concrete images, the same essence is revealed by classification, and its essence is condensed in concepts, and the relationship between various objects is expressed by the relationship between concepts, and the main characteristics and connections of objects are highlighted by words and symbols. For example, the main reaction process of photosynthesis, the graded regulation of thyroid hormone, is described graphically by photosynthesis.
3. Mathematical model: A mathematical model is a mathematical form used to describe a system or its attributes. The life essence and movement law of the research object are analyzed and synthesized in detail, and expressed in appropriate mathematical forms, such as mathematical equations, relationships, charts, tables, etc., so as to make judgments and predictions according to phenomena. For example, the high school part: Mendel hybridization experiment "tall stem: short stem = 3: 1", the schematic diagram of enzyme activity affected by temperature, etc. The junior middle school part includes: 1, the mathematical modeling explanation that cells cannot grow indefinitely (7; Unit 2 Chapter 2 Section 3 Cell Division); 2. Model construction of population change under "late childbearing" and "fewer births" (VII; Unit 4 Chapter 1 Section 4 Family Planning); 3. Construction of quantitative model of bacterial division and reproduction (8); Unit 5 Chapter 4 Section 2 Bacteria); 4. Mathematical modeling in the protective color formation experiment (8; Unit 7 Chapter 3 Section 3 Reasons for Biological Evolution).