2023 SASS Bio Prelims P2

Preliminary Examination 2023/4Exp/Biology Paper 2 3 [Turn over Section A [50 marks] Answer all questions. Write your answers in the spaces provided. 1 Aplastic anaemia is a rare blood disorder where stem cells in the bone marrow are damaged. Fig. 1.1 depicts the blood samples taken from a healthy individual and an individual with aplastic anemia. Fig. 1.1 (a) State one difference that can be observed in the two blood samples in Fig. 1.1. ………………………………………………………………………………………… ………………………………………………………………………………………[1] (b) Individuals with aplastic anemia may often experience light -headedness, especially when active or standing up. Explain why. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………[3] (c) Suggest an effect that aplastic anemia can have on the heart. Explain your answer. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………..…………………….[2] [Total: 6] red blood cell white blood cell red blood cell white blood cell healthy individual individual with aplastic anemia

Preliminary Examination 2023/4Exp/Biology Paper 2 4 2 Camellia sinensis is a widely grown plant as its leaves are used to make tea. A photomicrograph of a section through the midrib of the tea leaf is shown in Fig. 2.1. Fig. 2.1 (a) State the structural differences between (i) tissues A and B ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………[2] (ii) tissues C and D ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………[2] D A B C

Preliminary Examination 2023/4Exp/Biology Paper 2 5 [Turn over (b) The lower epidermis of the leaf contains many minute open ings called stomata. The opening and closing of each stoma is regulated by the guard cells surrounding it. In the space below, draw a labelled diagram of a pair of guard cells surrounding a single stoma. [3] (c) Camellia sinensis is mainly cultivated in tropical climates as it prefers a moist growing location. Explain how this affects the rate of transpiration of the plant. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………………..… [2] [Total: 9] 3 Fig. 3.1 shows the respiratory system of a human. Fig. 3.1 B A C

Preliminary Examination 2023/4Exp/Biology Paper 2