Christ Church Pure Biology Prelim 2024 Paper 1 & Paper 2 Answer

Christ Church Secondary School Preliminary Examinations Science Department Secondary Four Express Biology 1 Paper 1 [40 marks] Q Ans Q Ans Q Ans Q Ans 1 D 11 D 21 C 31 A 2 A 12 D 22 B 32 D 3 A 13 B 23 D 33 D 4 D 14 C 24 B 34 B 5 B 15 B 25 C 35 D 6 B 16 B 26 B 36 A 7 B 17 C 27 C 37 A 8 C 18 B 28 B 38 C 9 C 19 D 29 C 39 D 10 B 20 D 30 A 40 B Paper 2 Section A [70 marks] Answer Remarks Marks 1 (a) 1 testosterone 2 sperm 1 mark each R semen R hormone 2 (b) X: Sperm Duct Explanation: - Man is infertile / cannot reproduce - Sperms cannot travel to the urethra and out of the body 1 1 1

Christ Church Secondary School Preliminary Examinations Science Department Secondary Four Express Biology 2 (c) [1] When the valves malfunction/not working, backflow of blood occurs / blood flow backwards. [2] Blood vessels swell up and blood accumulates. [3] Accumulation of blood raises the temperature of the area/cells/tissues surrounding the testes. [4] The high temperatures causes lower sperm production and poor quality of sperms. 4 Total 9 Answer Remarks Marks 2 (a) [1] Cells in the trachea / bronchial tubes secretes mucus. [2] Mucus traps bacteria / germs / pathogens. [3] Cilia sweep the mucus containing bacteria / germs / pathogens upwards and out of the body / prevent it from entering lungs. 3 (b) [1] Vaccine contains an agent that resembles a pathogen. [2] Which stimulate white blood cells to produce antibodies. [3] These antibodies kill pathogens that cause infectious diseases. 3 (c) [1] Virus does not have cellular structures that antibiotic target. [2] Antibiotic acts on bacterial cell walls but viruses do not have cell walls. [3] Antibiotic break up cell membranes but viruses do not have cell membranes. [4] Antibiotic act on ribosomes inhibiting protein synthesis and growth but viruses do not have ribosomes and they do not grow. Any two points 2 Total 8

Christ Church Secondary School Preliminary Examinations Science Department Secondary Four Express Biology 3 Answer Remarks Marks 3 (a) [1] Blood flow remains constant and then increases. [2] Blood flow remains at 4/5 %. [3] Increase in blood flow from 25-27°C [4] to a maximum / 100% at 41°C. AW Any three points 3 (b) [1] Rise in temperature detected by receptor in skin and generate nerve impulses. [2] Nerve impulses generated travelled to the brain via the sensory neurone. [3] Impulses from the brain travelled to the muscles in the arterioles / shunt vessels via motor neurone. [4] Arterioles dilate / vasodilation OR shunt vessels constrict to increase more blood flow into capillaries / near the surface of the skin Any three points 3 (c) 46% 1 (d) [1] Higher concentration of capsaicin on the skin surface (than in the cells) [2] Capsaicin diffuse through the cells / passes through / across cell mem