How to Revise Topic 6: Immunity, Infection and Forensics — Edexcel A-Level Biology
Physiological mechanisms of the mammalian immune response are integrated with the biochemical and ecological principles utilized in forensic investigations. Non-specific and specific immune responses are analyzed, detailing the roles of B and T lymphocytes, cytokines, and the production of monoclonal antibodies in conferring immunity. Molecular techniques such as PCR and DNA profiling are applied to forensic science, alongside the analysis of decomposition and successional changes in necrophagous insects to estimate the post-mortem interval.
Examiner Tips for Topic 6: Immunity, Infection and Forensics
- Ensure you can define and apply Fick's Law to different biological contexts
- Practice drawing and interpreting genetic pedigree diagrams for monohybrid crosses
- Be prepared to discuss the ethical implications of prenatal screening using specific examples
- Understand the distinction between the roles of different membrane proteins
- Review the Meselson-Stahl experiment to explain how it supports semi-conservative replication
Common Mistakes in Topic 6: Immunity, Infection and Forensics
- Confusing the roles of carrier and channel proteins in membrane transport
- Incorrectly applying Fick's Law to non-gas exchange scenarios
- Failing to distinguish between the roles of DNA and RNA in protein synthesis
- Misinterpreting genetic pedigree diagrams
- Confusing the terms genotype and phenotype
- Inaccurate description of the fluid mosaic model
Key Marking Points
- Properties of gas exchange surfaces and Fick's Law of Diffusion
- Structure and properties of cell membranes and the fluid mosaic model
- Mechanisms of transport: diffusion, facilitated diffusion, active transport, endocytosis, and exocytosis
- Structure of DNA, RNA, and mononucleotides
- Protein synthesis: transcription and translation processes
- Nature of the genetic code: triplet, non-overlapping, and degenerate