Human Biology 4HB1/02R November 2020 | Edexcel IGCSE Past Papers With Mark Scheme

Edexcel International GCSE Human Biology (4HB1) Nov 2020

معلم موافق رایگان بودن است.

1. Digestive system: mouth to anus path (oesophagus, stomach, intestines), enzymatic breakdown (amylase, protease), fibre for bowel movement stimulation and preventing constipation.
2. Ebola case study: RNA virus definition, blood group compatibility for transfusion, donor infection screening (HIV, gonorrhoea), antibody transfer via recovered donor plasma, CWB storage limits (2–6 °C), virus base composition showing single-stranded RNA.
3. Circulatory system: heart bypass procedure (coronary artery blockage), affected heart tissue ischemia, bypass vessel restores blood supply to myocardium, vessel Y is coronary artery, vessel X connects to aorta.
4. Enzyme activity: temperature effect on bacterial enzyme vs. human enzyme, protein denaturation beyond optimum, high-temperature enzyme in thermophilic bacteria.
5. Nervous system and drug testing: atropine blocks vagus nerve, causes increased heart rate post-injection, experiment with 10 individuals increases result reliability, vagus nerve slows heart via parasympathetic signals.
6. Genetics and inheritance: haemophilia as sex-linked disorder (X chromosome), genotypes (e.g., XhXh, XHY), inheritance pattern prediction via pedigree, reduced frequency of haemophiliac individuals due to recessive allele lethality or lower reproductive fitness.