Some plants store starch as grains. Some starch grains have rings on the surface and the grains from different plant types differ in size and shape. You are required to: • observe and draw starch grains from two different types of plant • compare the starch grains from these two different types of plant. You are provided with starch grains, in water, from two different types of plant, labelled F and G. 1. Put one clean and dry microscope slide on a piece of black card with a paper towel underneath as shown in Fig. 2.1. black card starch grains in suspension slide paper towel [Figure 2.1] 2. Using a pipette put a few drops of F containing starch grains onto the slide. 3. Cover the starch grains with a coverslip and use a paper towel to remove any excess liquid that is outside the coverslip. 4. View the slide to observe the starch grains using the microscope. Select an area of starch grains on the slide. You may need to reduce the amount of light entering the microscope to observe the grains clearly. You must adjust the fine focus to observe the starch grains. 5. Select three starch grains which show the different sizes and features of the grains. 6. Make a large drawing in (a)(i) of the three starch grains that you have selected. 7. Remove the slide from the microscope and place on a paper towel. 8. Repeat step 1 to step 7 with G.

1. (a)(i)Use a sharp pencil for drawing. Make a large drawing of the three starch grains from F and the three starch grains from G. Use one ruled label line and label X to identify the surface markings of one starch grain. starch grains from F starch grains from G[5]
2. (a)(ii)Annotate your drawings in (a)(i) to describe three observable differences between the starch grains from F and G by: • drawing label lines to each of the features on the starch grains that show these differences • describing next to each line how each feature is different.[3]
3. (b)(i)A student investigated the effect of human salivary amylase on starch. 1 cm³ of salivary amylase was mixed with 10cm³ of a known concentration of starch and kept at 25 °C. The concentration of reducing sugar was measured at intervals for 60 minutes. All other variables were standardised. The results are shown in Table 2.1. Table 2.1 time /minutes reducing sugar concentration/µΜ 0 0.0 10 4.2 20 7.3 30 9.6 50 10.4 60 10.5 Use a sharp pencil for drawing graphs. Plot a graph of the data shown in Table 2.1.[4]
4. (b)(ii)Use your graph to calculate the percentage increase in concentration of reducing sugar between 15 minutes and 35 minutes. You may lose marks if you do not show all your working. % increase ....................................................................[3]
5. (c)Fig. 2.2 is a photomicrograph of a stained transverse section through a stem. You are not expected to be familiar with this specimen. [Figure 2.2] Observe the different tissues in Fig. 2.2 and select an area that shows part of the epidermis and the vascular bundles. Use a sharp pencil for drawing. Draw one large plan diagram from the selected area which shows: • part of the epidermis • only three vascular bundles • any other observable tissues. Use one ruled label line and label to identify the phloem.[5]

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.