S.5 Bio E.O.T 1 2026

SSEMATIM BA GODFREY 1 0756341741 ST. PETERS HIGH SCHOOL BUSABALA UGANDA AD VANCED CERTIFICATE OF EDUCATION COMPETENCE BASED ASS ESSMENT 2026 END OF TERM 1 EXAMS 2026 S.5 BIOLOGY 1 (THEORY ) TIME: 3 HOURS NAME………………………………………………………………………………………………………. SIGN………………. INSTRUCTIONS Attempt all items in Section A and Two items in Section B from each part. SECTION A (COMPULSOLY ) Item 1 A pharmaceutical company is developing a meth od to preserve human cells for transplantation. Two cell types (X and Y) were tested for membrane stability at increasing temperatures. The results are shown below Temperature (°C) Leakage in Cell X (%) Leakage in Cell Y (%) 20 5 8 40 10 20 60 25 55 Further analysis showed that Cell X contains more cholesterol than Cell Y Task a) Using the data, determine which cell type is more suitable for storage. Give reasons . b) Explain how cholesterol influences membrane behavior under temperature changes . SSEMATIM BA GODFREY 2 0756341741 c) Suggest why exces sive membrane rigidity could also be harmful to cells . d) Predict how both cell types would behave at temperatures below 0°C . e) Propose one improvement to the preservation method based on your understanding of membrane structure SSEMATIM BA GODFREY 3 0756341741 Item 2 A patient was found to have a metabolic disorder in which a key enzyme functions poorly out side a narrow pH range. Laboratory results are shown below: pH Enzyme Activity (%) 3 10 5 40 7 100 9 60 11 15 Task a) Suggest why this enzyme is highly sensitive to pH changes . b) Explain h ow a slight change in pH could lead to serious health problems in this patient . SSEMATIM BA GODFREY 4 0756341741 c) The patient develops a high fever. Predict how this may further affect enzyme activity …