Unlike Unit 3, which is coursework-based, Unit 4 is a written examination. It is typically sat by students in Year 13 (or the second year of A-Level study). The unit carries a significant weighting in the final A-Level grade, making proficiency in this paper non-negotiable for university aspirants, particularly those aiming for Medicine, Biomedical Sciences, or Genetics.
: Pay close attention to "Describe" vs. "Explain." Descriptions require what is happening; explanations require the biological "why." biology ial unit 4
You must explain how variation (through mutation and sexual reproduction) provides the raw material for natural selection. Unlike Unit 3, which is coursework-based, Unit 4
: Use technical terms precisely (e.g., phosphorylation , antigen-presenting cell , succession ) as mark schemes often require these specific words for full credit. IAL Biology Exam Paper WBI14/01 | PDF | Textiles - Scribd : Pay close attention to "Describe" vs
Open the official Edexcel IAL Biology specification. Go through each "bullet point" under Unit 4. If you cannot explain it in one sentence, you haven't learned it yet.
| Practical | Key method | Variables | |-----------|------------|-----------| | | Use a photosynthometer (bubbles of oxygen from pondweed) | Independent: Light intensity (use a lamp at varying distances) | | Rate of respiration | Use a respirometer (colorimeter or manometer) with soda lime to absorb CO2 | Independent: Temperature or type of organism | | Microbial growth | Use viable count (dilution plating) vs. total count (hemocytometer) | Independent: Antibiotic concentration | | Effect of IAA on shoots | Measure shoot length with different concentrations of auxin | Control: Distilled water |