中三BIOLOGY生物問題

All organisms consist of one or more cells. Cells are the basic unit of life.
The major groups of chemical substances in cells are carbohydrates, lipids, proteins, nucleic acids, water and inorganic ions. Each group has a unique basic structure and composition. Biomolecules (carbohydrates, lipids, proteins and nucleic acids), water and inorganic ions are the basic molecules of life. They contribute to the functioning of cells.

簡單來說，cells are the basic unit of life, while chemical constituents are the basic molecules of life.

2011-08-02 14:19:08 補充：
Among the many events that occur in the life of a cell are a multitude of specific chemical transformations, which provide the cell with usable energy and the molecules needed to form its structure and coordinate its activities.

2011-08-02 14:19:58 補充：
Four major groups of macromolecules are essential for the life of the cell: carbohydrates, lipids, proteins and nucleic acids. These four categories of molecules consist of very large organic compounds with an enormous variety in terms of function.

2011-08-02 14:20:55 補充：
Fortunately, the basic concept of their structure is a simple one: a large number of building blocks (monomers) are joined together with covalent bonds to form larger molecules (polymers). Their unique structures give them a variety of different functions within living systems.

2011-08-02 14:21:27 補充：
Natural selection and the process of evolution is the source of variety in structure and function in these molecules.

Cell is the building block of your body. Inside your cell, there are chemical constituents for communication and survival. For example, water is the essential solvent in your body, as well as a reaction medium for most of the chemical reactions. Carbon is the essential elements that is made up of fats, proteins. Fats and proteins are essential to build up your cell membrane, cytoplasm, etc. Nitrogen is needed for synthesis of protein.