A diagram of a chromosome from a dividing cell is shown in Fig. 1.1. [Figure 1.1]

1. (a)A dividing cell is at risk of losing genetic material each time DNA replication occurs. On Fig. 1.1, add a label line and the letter G to show the location on the chromosome of an area that helps to prevent the loss of genes.[1]
2. (b)The chromosome shown in Fig. 1.1 consists of one long DNA molecule associated with histone proteins. Name one stage of mitosis in which a chromosome would have the same general structure as the chromosome shown in Fig. 1.1.[1]
3. (c)Name the stage in the mitotic cell cycle during which the cytoplasm and the cell divide to produce two genetically identical daughter cells.[1]
4. (d)The control of the cell cycle can be affected by extracellular chemical messengers that bind to proteins and glycoproteins in the cell surface membrane. The overall mechanism is known as cell signalling. State the term used to describe the proteins and glycoproteins that function in this way.[1]

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