B6.3 Monitoring & Maintaining Health 1 Flashcards
Disease
A condition caused by any part of the body not functioning properly
Communicable disease
Diseases that can be spread between organisms
Pathogens
Microorganisms that cause disease when entering an organism
Non-communicable diseases
Cannot be spread between organisms
Examples of causes of non-communicable diseases
- poor diet
- obesity
- inheriting genetic disorder
- body processes not operating properly
Examples of linked communicable and non-communicable diseases
- HPV (Human Papilloma Virus) causes most forms of cervical cancer
- HIV (human immunodeficiency virus) causes AIDS (acquired immune deficiency syndrome) weakens a person’s immune system making it much easier for other microorganisms such as tuberculosis causing bacteria to cause disease
Ways in which pathogens spread between animals
- cuts through skin (injury, insect/animal bites)
- digestive system
- respiratory system (inhaling pathogens)
- reproductive system (sex)
Closer organisms live, greater risk of disease being passed on
Ways in which pathogens can spread between plants
- soil and water in which plant grow
- vectors (insects)
- direct contact of sap from infected and healthy plant (can be released by agricultural damage or animals feeding on plants)
- wind (fungal spores blown between plants, infected seeds)
Incidence of disease
Rate at which new cases occur in a population over a period of time
(Often monitored by scientists at disease outbreak)
Typical study for non-communicable diseases
Number of cases per 10000 people, per year, over 10 years
Steps to virus taking over host’s body
- Virus attacks a cell
- Inserts it’s genes
- ‘Tells’ nucleus to copy its genes
- New viruses made
- Cell bursts, releasing new viruses and destroying cell
Ways to prevent spread of communicable diseases
- covering mouth and nose when coughing/sneezing
- not touching infected people or objects
- using protection to prevent body fluids being exchanged (eg. Condoms)
- not sharing needles
How can being hygienic prevent communicable diseases
- wash hands before eating
- cooking food properly
- drink clean water
- protect from animal bites (insect repellant sprays)
How do farmers prevent spread of disease in plants and animals?
- Burn diseased plant material
- animals treated using drugs
- livestock cannot be moved
- chemical dips installed on farms to kill pathogens on footwear
- vaccinate animals
- spray plants with fungicide
What is athletes foot?
Caused by group of parasitic fungi called dermatophytes
Feet provide warm, humid environment ideal for them to live + multiply
Symptoms/ effects, treatment, of athletes foot
Cracked, flaking, itchy skin
Highly contagious, spread through direct contact and indirect contact
Treated using anti-fungal cream
What is food poisoning?
Caused by growth of microorganisms in food
Most serious types caused by bacteria and toxins they produce
Three main groups of bacteria which cause food poisoning
- Campylobacter- in raw meat, unpasteurised milk,untreated water
- salmonella- in raw meat, eggs, raw unwashed vegetables, unpasteurised milk
- E. coli- (only some types cause food poisoning eg. E.coli0157) in raw and undercooked meats, unpasteurised milk + dairy products
(All survive refrigeration and freezer storage but cooking kills them)
Common symptoms of food poisoning
Stomach pains
Diarrhoea
Vomiting
Fever
Sexually transmitted infections (STIs)
Passed on from one person to another through unprotected sex or genital contact
Passed through bodily fluids or skin contact
How to avoid STIs + symptoms
Abstain from sex or use condoms
Many initially have no symptoms
Chlamydia
- bacteria
- pain when urinating, discharge from penis/vagina
- antibiotics
Gonorrhea
- bacteria
- burning pain when jrinating, vaginal discharge
- antibiotics
Genital herpes
- virus
- painful blisters or sores
- no cure
HIV
- virus
- weakened immune system (often results in AIDS)
- no cure, symptoms controlled by antiretroviral drugs for life
What is HIV?
The human immunodeficiency virus
Invades white blood cells and reproduces inside cells, weakening immune system (as affected cells can no longer produce antibodies to defend against disease)
Body becomes target of everyday infections, cell changes that cause cancer
What is AIDS as opposed to HIV?
The final stage of the HIV infection when the body can no longer fight off life-threatening infections
What is tobacco mosaic virus
(Plant disease)
Attacks leaves, leaving them mottled or discoloured
—> prevents chloroplasts from forming, stunting growth of plant
(Almost never kills plants, lowers quality + quantity of crop)
How to prevent spread of tobacco mosaic virus
Remove infected plants
Wash hands and equipment between planting
Crops that are resistant to the virus planted on the previously infected area (avoids soil re-infecting)
What is crown gall disease?
(Plant disease) When bacterium agrobacterium tumefaciens (which has a large, Timor-inducing plasmid, containing genes for crown gall disease)
—> enters plant through wound, integrating into host’s genome, causing production of more growth chemicals than normal
= production of large, tumor-like growths called galls
—> galls encircle plant’s stem or trunk, cutting off flow of sap causing stunted growth and eventual death
How to prevent spread of crown gall disease
- destroy infected plants
- avoid planting other susceptible plants in area until bacteria die out for lack of host
What is powdery mildew?
Fungal (plant) disease
Caused by many different species of fungi
Infected plants display white spots/fungal growth on leaves and stem, reducing growth and making leaves drop off
= reduces crop yield by 10-15%
How does Powdery mildew spread?
Grows well in high humidity and moderate temperatures
—> survives between seasons on plant residues, releases spores which spread by wind to infect new crop
Controlled by spraying fungicide
Physical defences
Physical barriers that prevent microorganisms entering
Chemical defences
Substances secreted by plant that kills microorganisms
Cuticle
Waxy cuticle that covers the epidermal cells on most parts of plant above ground
- Prevents water loss,
- prevents pathogens from direct contact = limits infection
- Hydrophobic (water repelling) nature of cuticle prevents water collecting on leaf surface (many fungal pathogens require standing water on leaf for spore germination
Cell wall
Structural barrier
- cellulose fibres give strength and flexibility
- cellulose fibres cross linked with other substances (eg. Pectin) forming a gel to cement neighbouring cells
- secondary cell wall developed inside primary cell wall provides further support
- contains a variety of chemical defences that can be rapidly activated when cell detects pathogen
Examples of plant chemical defences
- insect repellents (repel insect vectors)
- insecticides (kill insects)
- antibacterial compounds (kill bacteria)
- anti fungal compounds (kill fungi)
- cyanide (toxic to most living things)
2 ways plants are diagnosed in the field
Observation - most plant diseases have visual effects
Microscopy - use microscopy to identify pathogen (symptoms of many plant diseases are similar)
2 ways plants are diagnosed in the laboratory
DNA analysis
Identification of antigens
(ADV = identifies plant pathogen before causing significant damage to crop)
How does DNA analysis of plant disease work?
Every plant pathogen has a unique genome which scientists identify using DNA fingerprinting
—> map of genome produced is called a DNA profile, if a match is found accurate diagnosis can be made
(Identifies individual strains of microorganisms)
How does Identification of Antigens work?
Plant pathogens carry specific antigens (proteins) on their surfaces which can be identified using chemical analysis
—> diagnostic kits help farmers identify common crop pathogens
