Human Biology 4HB1/02 November 2021 | Edexcel IGCSE Past Papers With Mark Scheme

Edexcel International GCSE Human Biology (4HB1) Nov 2021

معلم موافق رایگان بودن است.

1. Blood physiology: red blood cells transport oxygen using haemoglobin, lack nucleus for space, biconcave shape increases surface area, veins have valves and thin walls.
2. Enzyme and food testing: Benedict’s test for reducing sugars, protein detected in powder X, powder Y has most sugar, safety with heat and chemicals.
3. Thermoregulation: hypothalamus controls temperature, sweating cools via evaporation, motor neurones activate effectors, heat varies by activity, body size, and environment.
4. Dental health: wisdom teeth absent due to jaw size, sugar fuels bacteria to produce acid causing enamel decay, brushing and fluoride prevent caries.
5. Antibiotic effects: antibiotic B is bactericidal (kills bacteria), A is bacteriostatic (stops growth), Ebola not treatable with antibiotics, choice affects symptom severity.
6. Genetics: allele is gene variant, recessive only expressed when homozygous, haemophilia pedigree shows X-linked inheritance, more males affected, females often carriers.