How to Revise Topic 4: Biodiversity and Natural Resources — Edexcel A-Level Biology
Biodiversity encompasses the variety of alleles within a gene pool, the richness and evenness of species within a habitat, and the range of ecosystems within a biome. Natural selection acts as the primary mechanism for evolution, where advantageous alleles increase in frequency over generations, leading to anatomical, physiological, and behavioral adaptations. The conservation of these resources is critical for maintaining ecosystem services, requiring a balance between human development and the preservation of genetic diversity through in-situ and ex-situ methods such as seed banks and captive breeding programs.
Examiner Tips for Topic 4: Biodiversity and Natural Resources
- 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 4: Biodiversity and Natural Resources
- 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