A-LevelBiologyTransport in plants9700/33 · Feb/Mar 2017 · Q219 Marks

P1 is a slide of a stained transverse section through a plant root. You are not expected to be familiar with this specimen. Use a sharp pencil for drawing.

(a)(i)Draw a large plan diagram of the half of the root on P1 shown by the shaded area in [Figure 2.1]. Use one ruled label line and label to identify the xylem. You are expected to draw the correct shape and proportions of the different tissues.[5]
(a)(ii)Observe the central tissue in the root on P1. The cells in the central tissue are not identical. Select one group of four adjacent (touching) cells that show some of the differences between these cells. Each cell must touch at least two of the other cells. Make a large drawing of this group of four cells. Use one ruled label line and label to identify the cell wall of one cell.[5]
(b)(i)Identify the organ shown in [Figure 2.2]. Describe one observable feature that supports your identification. name of organ feature[1]
(b)(ii)The actual diameter of the organ in [Figure 2.2] along line Z is 4500 µm. Calculate the magnification of the organ shown in [Figure 2.2]. You may lose marks if you do not show your working. magnification x[4]
(b)(iii)Prepare the space below so that it is suitable for you to record the observable differences between the root on P1 and the organ in [Figure 2.2]. Record these differences in the space you have prepared.[4]

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Mark scheme

Marking points from the official mark scheme (Feb/Mar 2017). The mark or mark type is shown in brackets.

[5] (plan diagram of P1, Ranunculus root) 1 minimum size at least 90 mm + no shading; 2 no cells drawn + correct half of the root drawn ; 3 stele shown in correct proportion to width of root; 4 shape of xylem drawn correctly; 5 uses one label line + one label to xylem;
[5] (layout of drawing) 1 quality of line for outer wall of each cell, thin and sharp + minimum size of cell at least 40 mm; 2 only four cells drawn + each cell touching at least two other cells ; 3 cell wall drawn as two lines ; 4 one cell drawn with at least five sides; 5 uses one label line + one label to cell wall;
[1] (conclusion) 1 Fig. 2.2 identified as a stem + appropriate feature e.g. vascular bundles peripheral ;
[4] (calculation of magnification) 1 measures length of line Z + units ; 2 shows multiplication of length of line Z (mm) by 1000 to convert to m; 3 shows division of length of line Z by 4500; 4 final answer to appropriate degree of accuracy;
[4] (observable differences between the root on P1 and the organ in Fig. 2.2) 1 organises comparison into three columns with one column for features, one headed P1 and one headed Fig. 2.2 ; 2, 3, 4 any three observable differences of comparison ;;;

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