OCR AS Level Biology B PAPER 2 JUNE 2022 OFFICIAL QP H022 02 Biology in depth

OCR AS Level Biology B PAPER 2 JUNE 2022 OFFICIAL QP - H022/02 Biology in depth
AS Level Biology B (Advancing Biology) H022/02 Biology in depth 1 Fig. 1.1 shows a prepared slide of onion cells in different stages of mitosis, viewed using a light microscope. A B C Fig. 1.1 (a) (i) Name the stages of mitosis taking place in cells A and B. A ........................................................................................................................................ B ........................................................................................................................................ [2] (ii) Fig. 1.2 shows a student’s drawing of the cell labelled C in Fig. 1.1. Fig. 1.2 Give two improvements the student could make to their drawing. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2] (b) Fig. 1.3 shows the cell cycle in an onion cell. G1 checkpoint Fig. 1.3 Mitosis in an onion cell occurs once in 24 hours and lasts for 80 minutes. Metaphase takes approximately 6.5 minutes to complete. Calculate the percentage of the cell cycle which is spent in metaphase. Metaphase = % [2] (c) There are two main checkpoints in the cell cycle, the G1 checkpoint and the G2 checkpoint. Explain how each of the checkpoints can ensure the cell develops normally. G1 ............................................................................................................................................. ................................................................................................................................................... G2 ............................................................................................................................................. ................................................................................................................................................... [2] (d) The cell cycle is controlled by proteins. These proteins can initiate apoptosis. Describe the sequence of events that occurs during apoptosis. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3] 2 Lenticels appear as small brown patches on the surface of some fruit. A researcher wanted to investigate if water availability affected the number of lenticels on the surface of apples. They chose nine apple trees of one variety and watered each tree with a specific volume of water every day for twelve weeks. After twelve weeks they counted the total number of lenticels that developed on the surface of one apple from each tree. This was repeated with a second variety of apple. Fig. 2.1 shows the number of lenticels found on the surface of the two varieties of apple. 1200 1000 Number of lenticels 800 600 400 200 0 100 200 300 400 500 600 700 800 900 Volume of water added to the tree (cm3) Variety 1 Variety 2 Fig. 2.1 (a) (i) Using only Fig. 2.1, what conclusions can be drawn about the effect of water availability on lenticel number for these two varieties of apple? .
[2] (ii) Another researcher suggested that: ‘Adding a known volume of water to the tree is not a suitable method of investigating the effect of water availability on lenticel development.’ Evaluate this claim.