B6.3-part 1 Monitoring and maintaining health Flashcards

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1
Q

Describe the relationship between health and disease

A
  • if a person is in good health, they don’t have any type of disease
  • a disease is a condition caused by any body part not functioning properly
  • diseases can affect both mental and physical health
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2
Q

State the definition, causes and examples of communicable diseases

A
  • diseases that can be spread between organisms
  • also called contagious or infectious
  • most caused by microorganisms
  • most microorganisms cause no harm, but pathogens (microorganisms) cause disease when they enter the organism - these are parasites

Type of pathogen - example of animal disease - example of plant disease

Fungi - athlete’s foot - powdery mildew
Bacteria - tuberculosis - crown gall disease
Viruses - influenza (flu) - tobacco mosaic disease
Protozoa - malaria - coffee phloem necrosis

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3
Q

State the definition, causes and examples of non-communicable diseases

A
  • cannot be spread between organisms

Causes:

  • a poor diet - vegetable + fruitless diet can result in vitamin and mineral deficiencies
  • obesity - can lead to arthritis, type 2 diabetes, heart disease and stroke
  • inheriting a genetic condition - e.g. cystic fibrosis
  • body processes not operating correctly - uncontrollable cell division may lead to cancer
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4
Q

Describe the interactions between different types of disease (HIV and TB; HPV and cervical cancer)

A

Although most communicable and non-communicable diseases have separate causes, some conditions are linked.

HPV and cervical cancer

  • Human papilloma virus causes most forms of cervical cancer
  • periphery usually recover from an HPV infection without long term problems
  • in some cases, HPV causes cell changes that lead to cervical cancer
  • Girls in the UK are now routinely vaccinated against this virus, which has significantly reduced the no. of cases of cervical cancer

HIV and TB

  • human immunodeficiency virus, which causes AIDS (acquired immune deficiency syndrome), weakens a person’s immune system, making it much easier for other microorganisms, like the tuberculosis-causing bacteria, to cause disease
  • many people with HIV die from tuberculosis
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5
Q

Describe how communicable diseases can be spread between animals

A

Pathogens enter an animal’s body in order to cause harm:

  • through cuts in skin - from injury, or insect/animal bites
  • through digestive system - foods and drinks shared
  • through respiratory system - by inhaling pathogens
  • through reproductive system - during sexual intercourse

The closer together organisms live, the greater risk of a disease being passed on

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6
Q

Describe how communicable diseases can be spread between plants

A
  • through soil and water in which the plants grow
  • vectors, such as insects
  • direct contact of sap from an infected plant with a healthy plant. Sap can be released by agricultural damage, or through animals feeding on plants
  • the wind. Fungal spores can be blown between plants. Infected seeds can also be blown across large distances, resulting in the spread of a disease
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7
Q

Explain how pathogens cause disease

A
  • incubation period - time delay between harmful organisms entering body and you feeling unwell
  • during this period, pathogens reproduce rapidly
  • as they grow + reproduce they cause cell damage
  • some also produce toxic waste products - these toxins cause a range of symptoms like fevers, rashes and sores
  • Viruses can not replicate by themselves - they can only reproduce by ‘taking over’ and using a host organism’s cell to make more viruses
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8
Q

State the steps of viral replication

A
  • virus attacks a cell
  • inserts it’s genes
  • ‘tells’ the nucleus to copy its genes
  • new viruses are made
  • cell bursts, releasing the new viruses and destroying your cell
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9
Q

Explain how scientists monitor disease

A
  • for disease outbreaks they normally study the incidence of a disease - rate at which new cases occur in a population over a period of time
  • for non-communicable diseases, studies often last for long periods and involve many people
  • a typical study may look at the no. of cases per 10000 people, per year, over a 10-year period
  • outcomes from studies like these provide scientists with evidence for the effectiveness of disease treatments or prevention techniques
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10
Q

Explain how the spread of communicable diseases between humans (animals) can be reduced or prevented

A
  • covering your mouth + nose when coughing/sneezing - use a tissue and immediately discard it
  • not touching infected people or objects - e.g. chicken pox and mumps
  • using protection - e.g. condoms to help prevent STIs being transferred (body fluids prevents from being exchanged during sex)
  • not sharing needles - needles used to inject drugs should be disposed of immediately after single use - e.g. HIV and hepatitis can be passed on in blood on the needle

Being hygienic:

  • washing your hands - before eating
  • cooking food properly - some animals contain bacteria (E.coli, salmonella) which could cause food poisoning - thorough cooking kills bacteria
  • drinking clean water - untreated water contain microorganism that cause diseases like cholera and typhoid. Boil water / use sterilisation tablets
  • protect yourself from animal bites - use insect-repellent sprays
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11
Q

Explain how the spread of communicable diseases between animals and plants can be reduced or prevented

A

First, diseases are identified by changes to an organism’s appearance, or through identifying the pathogen by its DNA or antigens (proteins on surface of microorganism). Once identified:

  • diseased plant material is normally burnt to prevent disease spreading
  • animals may be treated using drugs although some communicable diseases require whole herds to be slaughtered
  • livestock cannot be moved
  • chemical dips are installed on farms to kill pathogens on footwear
  • farmers also spray plants with fungicides to prevent fungal disease
  • get their animals vaccinated against some pathogens
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12
Q

Describe common fungal infections (athlete’s foot)

A

Athlete’s food

  • caused by a group of parasitic fungi called dermatophytes
  • feet provide a warm, humid environment, ideal for dermatophytes to live and multiply in
  • symptoms (effects of disease) are cracked, flaking itchy skin
  • normally treated using an anti-fungal cream
  • very contagious - spread through direct and indirect contact
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13
Q

Describe common bacterial diseases (food poisoning)

A

Food poisoning

  • caused by growth of microorganisms in food
  • most serious types are caused by bacteria and the toxins they produce

3 main groups:

  • Campylobacter - found in raw meat, unpasteurised milk and untreated water
  • Salmonella - raw meat, eggs, raw unwashed vegetables and unpasteurised milk
  • E.coli - only some types cause food poisoning - found in raw and undercooked meats, and unpasteurised milk and dairy products
  • all these bacteria can survive refrigeration and freezer storage, but thorough cooking kills them
  • common symptoms - stomach pains, diarrhoea, vomiting and fever
  • most get better within a few days
  • in some cases, doctors may need to use a drip to replace fluids
  • in rare cases it can kill
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14
Q

Describe some examples of sexually transmitted diseases

A

STIs are passed on between people through unprotected sex or genital contact - passed on through bodily fluids or by skin on skin contact

  • people use condoms to protect themselves
  • many diseases initially don’t have symptoms so makes their spread more likely as people are unaware that they are infected

Infection - cause - symptoms - treatment
Chlamydia - bacteria - pain when urinating, discharge from penis/vagina - antibiotics
Gonorrhoea - bacteria - burning pain when urinating, vaginal discharge - antibiotics
Genital herpes - virus - painful blisters or sores - no cure
HIV - virus - weakened immune system, often resulting in AIDS - no cure, symptoms controlled with antiretroviral drugs. Lifetime treatment required

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15
Q

Explain the difference between HIV and AIDS

A
  • HIV invaded WBC and reproduces inside cells
  • this weakens your immune system as affected cells show be producing antibodies to defend against disease but cannot
  • without them, body becomes target of everyday infections and cell changes that cause cancer
  • AIDS is final stage of HIV infection, when body can no longer fight life-threatening infections like cancer
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16
Q

Describe a viral plant disease (tobacco mosaic virus)

A
  • virus attacks leaves, making them mottled/discoloured - does this by preventing chloroplasts from forming, which stunts growth of plant
  • virus almost never kills plants, but lowers quality + quantity of crop produced
  • to prevent spread, infected plants should be removed, and hands and equipment washed between panting
  • to avoid soil re-infecting the flowing year’s plants, crops that are resistant to the tobacco mosaic virus should be planted in previously infected areas
17
Q

Describe a bacterial plant disease (crown gall disease through A. tumefacians)

A

Agrobacterium tumefaciens

  • has large plasmid, known as a tumour-inducing plasmid - containing genes that cause crown gall disease
  • affects many plants (roses, fruit and nut trees)
  • bacteria enters plant through wound
  • plasmid integrates into host’s genome, and causes production of greater amounts of growth chemicals than normal
  • leads to production of large tumour-like growths called galls
  • as disease progresses, falls can totally encircle the plant’s stem/ trunk, cutting off the flow of sap - causes stunted growth and eventual death
  • to prevent its spread, infected plants must be destroyed + removed
  • planting other susceptible plants in are should also be avoided for 2 year, until bacteria die out for lack of host plant
18
Q

Describe a fungal plant disease (Powdery mildew)

A
  • Powdery mildew - fungi dies see affecting wide range of plants
  • caused by many different species of fungi
    E.g. Erysiphe graminis causes barley powdery mildew
  • infected plants display white powdery spots (fungal growth) on leaves + stems
  • fungus reduces growth, and makes leaves drop off early, reducing crop yield by 10-15%
  • powdery mildew grows well in areas of high humidity + moderate temps
  • survives between seasons on plant residues
  • it then releases spores, which are spread by wind to infect the new crop
  • can be controlled by spraying crop with a fungicide
19
Q

Describe physical plant defence responses to disease

A

Cuticle

  • epidermal cells of most parts of the plant above the ground are covered in a waxy cuticle
  • prevents water loss from plant
  • prevents pathogens from coming into direct contact with epidermal cells, limiting chance of infection
  • Cuticles can be relatively thin (aquatic plants), or extremely thick (cactus)
  • the hydrophobic (water repelling) nature of cuticle prevents water from collecting on leaf surface
  • this is an important defence against many fungal pathogens, as most require standing water on leaf surface for spore germination

Cell wall

  • major defence against fungal + bacterial pathogens
  • provides excellent structural barrier
  • all plants cells have a primary cell wall that provides structural support - composed of mainly cellulose fibres, giving strength + flexibility
  • these fibres cross-link with other substances like pectin - forms a gel that helps to cement neighbouring cells together
  • many cells also form a secondary cell wall, which develops inside primary cell wall - provides further structural barrier
  • cell walls also contain a variety of chemical defence that can be activated rapidly when cells detect pathogens
20
Q

Describe chemical plant defence responses

A
  • insect repellents to repel insect vectors that carry disease (e.g. pine resin, citronella from lemon grass)
  • insecticides to kill insects (pyrethrins made from chrysanthemums)
  • antibacterial compounds to kill bacteria (e.g. phenols disrupt bacterium’s cell wall, defending disrupt cell membrane)
  • antifungal compounds to kill fungi (chitinases - enzymes that break down chitin in fungal cell walls; caffeine - toxic to fungi + insects)
  • cyanide - some plants make chemicals that break down to form cyanide compounds when the plant cell is attacked - toxic to most living things
21
Q

Describe how plant diseases can be detected in the field

A

Observation
- most plants have visual symptoms
E.g.
- strawberry mottle disease - viral - discoloured leaves
- bacterial soft rot - bacteria - rotting of plant’s leaves/fruit
- powdery mildew - fungal - White, powdery deposit on plant - repeated infection weaken tree and reduce its yield

Microscopy

  • often symptoms of many plant diseases are similar
  • plant pathologists use microscopy to identify pathogen e.g. identify species of bacteria by their shape
  • electron microscopes sometimes required for accurate diagnosis (identifying existence of disease)
  • but plant disease can only be identified in field once an infection had taken hold, and symptoms become apparent
22
Q

Describe how plant diseases can be detected in the laboratory

A

DNA analysis

  • every plant pathogen has unique genome - identified using DNA fingerprinting
  • map of genome produced - profile
  • scientists compare unknown plant pathogen’s genome to a known DNA profile
  • if match is found, accurate diagnosis can be made
  • DNA profiles can be used to identify individual strains of microorganism

Identification of antigens

  • plant pathogens carry specific antigens (proteins) on their surfaces
  • these can be identified through chemical analysis, so the pathogen can be identified
  • scientists have developed diagnostic kits to enable farmers to identify common crop pathogens
  • key advantage of both lab-based techniques is the potential to identify a plant pathogen before it causes significant damages to a crop