Fig. 6.1 is a diagram of a vertical section of the human heart and the associated blood vessels. [Figure 6.1]

1. (a)Complete Table 6.2 by writing the letter from Fig. 6.1 that identifies each of the structures described. Table 6.2 structure in the heart letter valve preventing back flow of blood into a ventricle blood vessel carrying blood under highest pressure chamber that pumps blood to the lungs[3]
2. (b)Describe the short-term effects of nicotine on the cardiovascular system.[3]
3. (c)(i)Cardiac myocytes are heart muscle cells. Fetal cardiac myocytes are present before birth and divide rapidly during fetal development. Soon after birth the cell cycle in most of these fetal cardiac myocytes stops, forming adult cardiac myocytes. Most of the adult cells have completed the cell cycle but in some the cell cycle stops at the end of mitosis. State the difference between adult cardiac myocytes that have completed the cell cycle and those that have stopped at the end of mitosis.[1]
4. (c)(ii)Suggest why it could be a disadvantage that the cell cycle has stopped in most adult cardiac myocytes.[2]

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