Module 4 Bio

  • Created by: Jessinoch
  • Created on: 11-05-18 12:14
How does bacteria cause disease?
Damages cells or produces toxins that are harmful - rapidly multiply
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How do viruses cause disease?
Invades cells and takes over protein-synthesising organelles by infecting the cells with new DNA and the host cells eventually burst and release new copies of the viral DNA
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How does fungi cause disease?
In animals causes redness & irritation due to hyphae released from fungus
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How does protoctista cause disease?
Feed on cell contents as they grow
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What are the 5 types of transmission of disease?
1. Droplet (pathogen in mucus - direct) 2. Physical Contact (direct) 3. Faecal-oral (consumption of food/water with faeces - direct) 4. Transmission by spores (spores are a resistant form of pathogen - direct) 5. Vector Transmission (indirect)
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What are the environmental factors that contribute to disease?
1. Climate - some vectors only live in certain climates, many viruses live better in hot temp, cold temp kills pathogens 2. Cramped & crowded environments increases droplet and contact infection 3. Dirty environments harbour pathogens
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What physical barriers do plants have to fight off pathogens?
1. Cellulose cell wall 2. Lignin thickening of cell walls 3. Waxy cuticles 4. Bark 5. Closed stomata 6. Callose (blocks pathogen movement in sieve plates) 7. Tylose (blocks xylem to prevent pathogen movement)
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What are the active defences that plants have to fight off pathogens?
1. Leaves sense presence of pathogens and begin to prioritise use of energy in secreting harmful chemicals 2. Cellulose produced to further fortify walls 3. Oxidative bursts produce harmful oxygen molecules to target pathogen
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What is a primary defence?
Prevent pathogens from entering the body
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What is a secondary defence?
Prevent pathogens from harming the body once it has infected the host
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What is a non-specific defence?
Occur in the same way, no matter the pathogen and don't require identification of the antigen
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What is a specific defence?
Are immune responses carried out by the host which specifically target the pathogen
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What are the primary, non-specific defences against pathogens in animals?
1. Skin 2. Mucous Membranes 3. Blood Clotting & Skin Repair 4. Inflammation 5. Coughing & Sneezing
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Why is the skin a good defence against pathogens?
1. Epidermis - tough outer layer secreting sebum to waterproof skin and keratin to toughen it 2. Dermis - 20-40x thicker than epidermis
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What are phagocytes are what are the two types?
A type of white blood cell. Neutrophils - multi lobed nucleus enhancing flexibility, short-lived, released in large numbers. Macrophages - larger cells, both are manufactured in bone marrow
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What is the mode of action of a phagocyte?
1. Envelopes and engulfs pathogen 2. Membrane folds inwards via phagocytosis 3. Pathogen trapped inside phagosome vesicle 4. Lysosome fuses with phagosome making phagolysosome 5. Releases lysins inside to digest bacterium 6. Products then exocytosed
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What are B Cells
1. Plasma cells - circulate in blood, produce and secrete antibodies 2. B-Memory Cells - remain in body for many years after infection to remember antigen
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What are T Cells
1. T helper cells - release cytokines, stimulates B cell maturation, promote phagocytosis 2. T killer cells - identify and kill infected host cells 3. T memory cells - long term immunity 4. T regulator cells - stops immune response when pathogen gone
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What is the structure of antibodies?
4 polypeptide chains held together by disulphide bridges, constant regions bottom three which remain same, variable regions at very top two changes, hinge regions for flexibility, antigen bonding sites at very top two (weird shape)
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What is neutralisation?
When antibodies attach to antigens on a pathogen and block their bonding site, preventing pathogen from binding to host cells
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What are agglutinins?
Large antibody that binds many pathogens together and immobilises them, preventing them from entering cells as they are now too big
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What are antitoxins?
Antibodies can bind to toxins released by the pathogens, rendering them harmless
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What are opsonins?
Antibodies can label the pathogens as foreign to phagocytes, speeding up the process of phagocytes identifying antigens
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What is active artificial immunity?
Immunity provided by antibodies made as a result of an injection, person injected with weakened virus
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What is active natural immunity?
Immunity provided by antibodies made in immune system as result of infection
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What is passive artificial immunity?
Immunity provided by injection of antibodies made by another individual
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What is passive natural immunity?
Antibodies provided by the placenta or breast milk, making baby immune to diseases that the mother is immune to
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What is herd immunity?
Provides vaccination to all population at risk, once enough people are immune the infection will stop spreading
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What is ring immunity?
Used when new cases of disease are reported, people in immediate vicinity of new cases are vaccinated
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Define species
A group of individual organisms that are very similar in their appearance, anatomy, physiology, biochemistry and genetics and where the members are able to interbreed freely to produce fertile offspring
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How can you sample animals?
Sampling may disturb the habitat and animals may be frightened away giving an unrepresentative sample, animals can be caught using swamp netting, collecting from trees, pitfall trap, tullgren funnel or a light trap
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What human activities contribute to loss of biodiversity?
Hunting for food, over harvesting, killing for protection, killing to remove competitors, pollution, habitat destruction, population growth
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What are the consequences of climate change?
1. Migration 2. Agriculture 3. Diseases
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What are the reasons to maintain biodiversity?
1. Moral reasons 2. High value natural ecosytems (regulates atmosphere, purifies water, recycles nutrients, growth of timber and food etc) 3. Aesthetic reasons (good for mental health, all organisms have right to live) 4. Medicines
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What is In Situ Conservation?
Attempting to minimise human impact on the environment by protecting it via legislation, conservation parks, repopulation
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What is Ex Situ Conservation?
Conservation of endangered species outside of their natural environment via zoos or seed banks
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What are the pros and cons of zoos?
Pros: lowers likelihood of extinctions, release them into the wild afterwards, prevents endangered species / Cons: animals not kept in their natural environment
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What are the pros and cons of a seed bank?
Pros: have a collection of seed samples, seeds have infinite options for use in the future / Cons: storage MUST be controlled and germination must be annually checked
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What are the pros and cons of legislation?
Pros: prevents hunting & land clearing / Cons: prevents development/human activities and is hard to enforce in smaller countries
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What are the pros and cons of a conservation park?
Pros: permanent protection in natural environment / Cons: conflict may arise if animals escape
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What are the pros and cons of repopulation?
Pros: rebuilds habitats to improve biodiversity and stop extinction / Cons: may cost a lot and there is an unknown impact on the environment
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What is CITES?
Convention of International Trade in Endangered Species - regulates trade in selected species so animals do not become endangered
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What is the agreement on conservation on biodiversity?
Can use nature for resources, whilst promoting biodiversity
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What is EIA?
Undergoes environmental impact assessments to avoid adverse impacts on the environment
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Define phylogeny
The study of evolutionary relationships between organisms
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Define taxonomy
Study of differences between species
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Why do we classify things?
1. For our convenience 2. To make studying them/identifying them easier 3. To put them in order to see their relationships
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What are the 5 kingdoms?
1. Prokaryote 2. Protoctista 3. Fungi 4. Plantae 5. Animalia
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How can you use biochemistry to see differences/similarities between species?
1. Cytochrome C is made from smaller sequences of amino acids, if the sequence is similar, the organisms are closely related 2. DNA - the more similar the sequence, the more closely related the species
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What were Darwin's 4 observations?
1. Offspring generally appear similar to their parents 2. No two individuals are identical 3. Organisms have the ability to produce large numbers of offspring 4. Populations in nature tend to remain fairly stable in size
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What were Darwin's 3 conclusions?
1. There is a struggle to survive 2. Better adapted individuals survive and pass on their characteristics 3. Over time, number of changes gives rise to a new species
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What is interspecific variation / infraspecific variaton?
Interspecific can occur between individuals of different species, whereas intraspecific can occur between members of the same species
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What is discontinuous variation?
Distinct categories like eye, gender due to genetics like independent assortment of chromosomes, crossing over and mutations
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What is continuous variation?
Full range of intermediate values like height, length of leaves due to environmental causes like how sunbathing causes skin darkening and lack of balanced diet causes poor growth
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How does natural selection occur?
1. Gene mutates to create new allele 2. Mutated allele beneficial to organism and members with this mutation more likely to survive and reproduce 3. Mutated allele becomes more common as inherited and over time population becomes better adapted
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What are the selective forces on survival?
1. Availability of food 2. Predators 3. Disease
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Define speciation
Formation of a new species from an existing one
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How do viruses cause disease?


Invades cells and takes over protein-synthesising organelles by infecting the cells with new DNA and the host cells eventually burst and release new copies of the viral DNA

Card 3


How does fungi cause disease?


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Card 4


How does protoctista cause disease?


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Card 5


What are the 5 types of transmission of disease?


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