Topic 1
Plant transport systems
Coursebook section 8.1 Teaching ideas ◆
You could begin the lesson with Activity 8.1 Identify the positions of xylem vessels in roots, stems and leaves. ◆ Activity 8.2 To see which part of a stem transports water and solutes could also be carried out at this point. Students can relate what they see to the structures shown in Figure 8.7, and discuss the positions of xylem in the stem and in roots. Students will probably know the terms ‘xylem’, ‘phloem’ and ‘vascular bundle’ from their earlier work on leaves. ◆ If students are working at wooden desks, they will probably be able to see xylem vessels in section. ◆ Micrographs and Figures 8.6 and 8.7 can be used to identify the positions of phloem. Common misunderstandings and misconceptions ◆
Students may find it difficult to visualise the three-dimensional arrangement of xylem vessels from looking at a transverse section, and may therefore not appreciate that continuous vessels run from the roots all the way up the stem and into the leaves.
Homework ideas ◆ ◆
Coursebook questions 8.1 to 8.5 End-of-chapter question 4
Topic 2 Water uptake Coursebook section 8.2 Teaching ideas ◆
Show students bean or other seedlings with root hairs – these are usually clearly visible if the seeds are germinated in damp filter paper. Ask them what they think the root hairs do and discuss the very large surface area they provide. ◆ Draw a diagram of a root hair cell on the board. Ask students to think back to what they know about osmosis and to suggest how water gets inside a root hair cell. ◆ Use Figure 8.10 in the Coursebook to discuss how water moves from the outside of a root to the centre and into the xylem vessels. Use Figure 8.11 to introduce the idea of the transpiration stream. Common misunderstandings and misconceptions ◆
Students often do not realise that water has to move horizontally from the outside of the root into its centre, before it can enter a xylem vessel.
Homework ideas ◆ ◆ ◆
Coursebook questions 8.6 and 8.7 End-of-chapter question 6 Worksheet 8.1 The pathway of water movement through a plant
Original material © Cambridge University Press 2014 © Cambridge University Press 2014
IGCSE Biology
Chapter 8: Teaching ideas
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