The diagram shows an elm tree. [Figure 3.1]

1. (a)Elm trees may be infected by a fungus that causes a disease. State two characteristics of a fungus. 1 2 [2][2]
2. (b)The fungus moves through an infected tree inside the xylem vessels. The tree responds to stop the movement of the fungus by producing substances that block the xylem vessels. This causes the leaves of the tree to wilt and to become yellow. Explain how the response of the tree to infection leads to these symptoms of disease. [5][5]
3. (c)An insect called the elm bark beetle is the vector of this disease. Describe what is meant by the term vector. [2][2]
4. (d)(i)Elm trees can reproduce when the roots from one parent tree spread out near the surface of the soil. This is shown in the diagram below. [Figure 3.2] Name the type of reproduction shown in the diagram. [1][1]
5. (d)(ii)Suggest why this type of reproduction makes it difficult to control the spread of the disease caused by the fungus. [3][3]

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