Chapters 1 & 2

Cell Variety & Absorption and Secretion

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1. The is the basic unit of life.

2. A organism consists of one cell which possesses a variety of structures enabling it to perform all the functions necessary for the maintenance of life.

3. A organism consists of more than one cell. In advanced animals and plants these are arranged into tissues giving a division of labour.

4. in cell structure exists between cells of one type of tissue and cells of different tissues since cells are to perform particular functions.

5. Cells absorb molecules in solution by , osmosis and active .

6. The cell wall surrounding plant cells is made of and is permeable to solutions. It prevents the cell from when water is absorbed.

7. The plasma surrounding the living contents of all cells is selectively . It consists of protein and molecules thought to be arranged as in the fluid model.

8. Tiny channels in the plasma membrane make it and allow the transport of small molecules by diffusion and osmosis along a concentration .

9. Other chemical substances such as ions are transported across the plasma membrane a concentration gradient by carriers. This process requires .