2.1Variation, Homeostasis and Micro-organisms
Classification and Biodiversity — WJEC GCSE Biology — WJEC GCSE Biology Revision Notes & Topical Questions
5 min read 2 parts Lesson 1 of 3
Section 1 of 2Classification systems and binomial naming
- Five Kingdom Classification System:
Kingdom Cellular Organization Nuclear Membrane Cell Wall Nutrition Animals Multicellular Present Absent Heterotrophic (ingest food) Plants Multicellular Present Present (cellulose) Autotrophic (photosynthesis) Fungi Multicellular (moulds) or Unicellular (yeast) Present Present (chitin) Saprotrophic (absorb digested nutrients) Protoctists Mainly unicellular Present Variable Autotrophic or heterotrophic Prokaryotes (Bacteria) Unicellular microscopic Absent Present (murein) Autotrophic or heterotrophic - Binomial scientific nomenclature:
- Two-part Latin name: Genus (capitalised) followed by species (lowercase), e.g. Homo sapiens.
- Universal across all languages, avoiding ambiguities of local common names.
- Modern classification: Uses morphological adaptations combined with DNA profiling and base sequence comparisons; more closely related species have more similar DNA base sequences.
Section 2 of 2Biodiversity and conservation
- Biodiversity: The variety of different species, and the number of individuals of each species, within a habitat.
- Reasons to conserve biodiversity:
- Maintains ecosystem stability and food web complexity.
- Preserves potential future medical pharmaceuticals from undiscovered plant/microbe compounds.
- Provides genetic resources for crop breeding and biological pest control.
- Conservation methods: National parks, legal protection of endangered species, seed banks, and captive breeding programmes with reintroduction.
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