Biology 2023 · May/June

L1 is a slide of a stained transverse section through a plant root.

(i) Draw a large plan diagram of the whole section on L1. Use a sharp pencil. Use one ruled label line and label to identify the cortex.

Observe the xylem on the section of the root on L1. Select a group of four adjacent xylem vessel elements. Each xylem vessel element must touch at least two other xylem vessel elements. element.

Describe one observable feature that you used to identify the cells on L1 as xylem vessel elements.

Fig. 2.1 is a photomicrograph of a stained transverse section through a different plant and a different organ.

Identify three observable differences, other than colour, between the section on L1 and the section in Fig. 2.1. Record the three observable differences in Table 2.1. Table 2.1 feature L1 Fig. 2.1

Describe one observable similarity between the vascular bundle on L1 and the vascular bundle in Fig. 2.1, other than that they both contain xylem and phloem.

Fig. 2.2 is the same photomicrograph as that shown in Fig. 2.1 with the line P-Q added. 150 μm Use the scale bar to calculate the actual length of line P-Q. Show your working and use appropriate units. actual length of P-Q = [4] [Total: 20] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.