Biology: OCR Module 4 - Biodiversity, Evolution, and Disease
Overview
Focus on three key areas:
Communicable diseases, disease prevention, and the immune system
Communicable diseases caused by pathogens (bacteria, viruses, protoctista, and fungi)
Diseases can damage tissue or release toxins
Communicable Diseases
Bacterial Diseases
Tuberculosis: Affects humans, deer, cows, pigs, and badgers. Transmitted through airborne droplets. Curable with antibiotics and preventable via vaccination.
Ring Rot: Affects potatoes, tomatoes, and aubergines. Transmitted through infected tubers. Impacts crop yield and farmer's livelihood.
Viral Diseases
HIV: Leads to AIDS. Transmitted through bodily fluids. Interferes with immune system functioning.
Influenza: Infects ciliated cells. Transmitted by airborne droplets.
Tobacco Mosaic Virus: Affects plants. Causes leaf damage. No cure.
Protoctista
Malaria: Caused by Plasmodium, transmitted by mosquitoes. Affects red blood cells, liver, and brain. No vaccine or cure.
Potato Blight: Caused by fungus-like protoctista. Damages plant leaves and fruit.
Fungi
Black Sigatoka: Affects bananas. Transmitted by spores.
Athlete's Foot: Infects humans. Causes itchy, scaly skin. Transmitted by direct contact.
Pathogen Transmission
Animals: Direct (contact, inoculation, ingestion) and Indirect (vectors, droplets, fomites)
Plants: Direct or indirect transmission
Defense Mechanisms
Plants
Physical barriers like bark and wax
Produce antibacterial chemicals
Animals
Primary Defense: Skin, mucous membranes, blood clots, and inflammation
Secondary Defense: Specific immunity involving B and T lymphocytes
Immune System
Phagocytosis
Non-specific response by phagocytes (macrophages or neutrophils)
Specific Immune Response
T Lymphocytes: Cell-mediated response
Helper T cells, Killer T cells, Memory T cells, Regulator T cells
B Lymphocytes: Humoral response
Plasma cells produce antibodies
Memory B cells for rapid response on reinfection
Types of Immunity
Passive Immunity: Introduction of antibodies (e.g., via placenta or breast milk)
Active Immunity: Created by exposure to pathogens or antigens
Natural: Previous infection
Artificial: Vaccination
Vaccines
Provide individual and herd immunity
Antigen variability may reduce long-term effectiveness
Antibiotics
Originated from microorganisms
Overuse leads to resistance
Biodiversity
Importance
Drugs sourced from plants and microbes
Genetic diversity aids in discovering new drugs
Measuring Biodiversity
Species Diversity: Number and abundance of species
Genetic Diversity: Polymorphic gene loci
Habitat Diversity: Different habitats present
Calculations
Simpson's Index of Diversity: Measures biodiversity in habitats
Ecological, economic, and aesthetic reasons for maintaining biodiversity
Conservation
In Situ: Within natural habitat
Ex Situ: Outside natural habitat
Classification and Evolution
Classification Systems
Phenetic Classification: Based on evolutionary origins
Linnaean System: Hierarchical classification
Binomial System: Universal naming
Advances in Classification
Based on molecular similarities
Introduction of three-domain system
Natural Selection and Evolution
Process of evolution through natural selection
Evidence from fossils and molecular biology
Types of Adaptations
Anatomical, physiological, and behavioral adaptations
Variation
Intraspecific: Within the same species
Interspecific: Between different species
Continuous vs Discontinuous Variation
Conclusion
Understanding the interaction between biodiversity, evolution, and disease is crucial for developing effective strategies for conservation and disease prevention.