Communicable diseases - GCSE Biology

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it can be treated by antibiotics. However, there are antibiotic resistant strains of gonorrhoea There is no vaccine to prevent the spread of gonorrhoea, a barrier method may be used instead Bacterial Disease in Plants Symptoms: Agrobacterium tumefaciens Crown galls (a mass of unspecialised cells that often grow at the joint between the root and the shoot in the infect plant) Usually found in tropical and sub-tropical regions. Bacteria inserts plasmids into the plant cells and cause a mass of new undifferentiated genetically modified cells to grow. These bacteria have become a key tool for scientists when genetically modifying plants. Scientists make use of the way the bacteria naturally infect plant cells and give them new added genes. They manipulate the bacteria so they carry desirable genes into the cells they infect Fungal Diseases Symptoms: Irritation. Scaly skin. Redness. Itching. Swelling. When fatal they attack the lungs or brains of people who already feel ill. Damaged heart valves can also develop fungal infections Treatment: Antifungal drugs are usually effective against the skin fungi. It is harder to treat deep-seated tissue infections In Plants: - Common Crops lost from fungal infections, including stem rusts and various rotting diseases Symptoms: - Rose Black Spot Purple or black spots on the leaves Spread: in the environment carried by the wind. Spread over the plant after it rains in drips of water that splash from one leaf or plant to another. Spores stay dormant over winter on dead leaves and on the stem Leaves turn yellow and drop early Causes: Weakness in the plant as it reduces the are of leaves available for photosynthesis. Plant does not flower wll Treatment: Prevent the spread by removing and burning affected leaves and stems Chemical fungicides can treat the disease and prevent it spreading. Types of roses have been bred that are relatively resistant to black spot but the disease still cannot be prevented or cured. 5 μm Protists are a type of single-celled organism that cause a range of diseases in animals and plants. Disease caused by Protists Disease caused by protists usually involve a vector that transfers the protist to the host. An example of a serious protist disease is malaria Relatively rare pathogens but the diseases they cause are serious and damaging. Affect the: Liver Damage red blood cells - Causes: Fever - Shaking when the protists burst out of the blood cells Weakens affected person over time Caused by protist pathogens that are parasites - live and feed on other living organisms. Life cycle of protists includes time in human body and time in the body of a female Anopheles mosquito. Protists reproduce sexually in the mosquito and asexually in the human body. The mosquitoes act as vectors of the disease. Female mosquito needs two meals of human blood before she can lay her eggs (this is when the protists are passed into the human bloodstream. The protists travel around the body in the circulatory system. Malaria Treated using a combination of drugs, not always available in the countries most affected. Protists have become resistant to some of the most commonly used medicines. Treated by targeting the mosquito vector: Insecticide-impregnated insect nets to prevent mosquitoes biting humans - Insecticides to kill mosquitoes in homes and offices Preventing the vectors from breeding by removing standing water and spraying water with insecticides to kill larvae Travellers take antimalarial drugs that kill the parasites in the blood if they are bitten