A-LevelBiologyTransport in plants9700/33 · Oct/Nov 2025 · Q220 Marks

K1 is a slide of a stained transverse section through a root.

(a)(i)Draw a large plan diagram of the region on K1 indicated by the shaded area in Fig. 2.1. Use a sharp pencil. Use one ruled label line and the label T to identify a tissue involved in transport of substances throughout the plant. [Figure 2.1][5]
(a)(ii)Observe the cells in the centre of the root on K1. Select a group of four adjacent cells. Each cell must touch at least one of the other cells. Make a large drawing of this group of four cells.[4]
(b)Fig. 2.2 is a photomicrograph of a stained transverse section through the root of a different plant to K1. One difference between the section in Fig. 2.2 and the section on K1 has been labelled. Identify three other observable differences between the section in Fig. 2.2 and the section on K1. Draw three label lines on Fig. 2.2 to label the three differences you have identified. You should complete the labels to describe the differences you observe. [Figure 2.2][4]
(c)(i)A student was asked to find the area of the vascular tissue in a transverse section of root. The student grew one plant for three weeks and took a section from one of the roots. This section is shown in Fig. 2.3. [Figure 2.3] The vascular tissue is the central region of the section. Assume that the vascular tissue is a circle. The line A-B is the diameter of the vascular tissue. Calculate the actual area of the vascular tissue. Use the formula: area = πr², where π = 3.14. actual area of the vascular tissue = .................................................... mm²[4]
(c)(ii)The student wrote a hypothesis which stated that: The area of vascular tissue in a root section changes as the plant grows. Suggest modifications to the method used in (c) to investigate this hypothesis.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

2(a)(i) 1 uses most of the available space and the correct number of tissues ;
2(a)(i) 2 draws half the root and no cells ;
2(a)(i) 3 draws the outer region of the vascular tissue as 2 lines drawn close together;
2(a)(i) 4 draws the correct proportion of the vascular tissue ;
2(a)(i) 5 label line to the tissue involved in transport of substances throughout the plant and the label T ;
2(a)(ii) 1 lines continuous, thin and sharp and no shading;
2(a)(ii) 2 draws only four cells and each cell touching at least one of the other cells ;
2(a)(ii) 3 cell wall drawn as two lines ;
2(a)(ii) 4 correct shapes of the cells ;
2(b)(i) 1 states only observable differences ;
2(b)(i) (differences) 2, 3 and 4 ;
2(b)(i) Any three from : feature Fig. 2.2 K1 area of vascular tissue larger smaller ;
2(b)(i) presence of trichomes absent present ;
2(b)(i) number of xylem vessels more less ;
2(b)(i) presence of endodermis absent present ;
2(c)(i) 1 records a value for the length of the line A-B;
2(c)(i) 2 shows the length of line A – B divided by 35 to calculate actual length of line A -B;
2(c)(i) 3 shows ½ actual length of line A – B squared and multiplied by π ;
2(c)(i) 4 correct answer ;
2(c)(ii) 1 take sections of the root from plants at different ages ;
2(c)(ii) 2 keep the species of the plants the same ;
2(c)(ii) 3 keep the variables for growing the plants the same ;