Topic 5

Created by

Naomi A

Cards (100)

Define health 
A state of complete physical, mental, and social well-being
Define disease 
A disorder of the body or mind that negatively affects an individual's health
What is a communicable disease
A disease that is passed directly between individuals. It is caused by a pathogen
Define Pathogen 
disease causing microorganism
What is a non-communicable disease?
A disease that cannot be passed from person to person
What is a symptom 
A change in body function that is felt by a patient as a result of disease
Why does having an illness make an individual more likely to contract another disease?
A disease may weaken an individual's immune system making them increasingly susceptible to other infections.
Describe cholera 
● Caused by Vibrio cholerae bacterium
● Spread by drinking water or washing in water that has
been contaminated with infectious faeces
● Symptoms: diarrhoea, vomiting
How can the incidence of cholera be reduced?
● Access to clean water
● Improved sanitation (sewage disposal etc.)
Describe Tuberculosis 
- Caused by Mycobacterium tuberculosis bacterium
- It is an airborne bacteria spread by droplet infection
- Symptoms: lung damage, chesty cough, wheezing
How can the transmission of TB be reduced?
- Improved hygiene (washing hands, sneezing into tissues etc.)
- Infected individuals should avoid crowded areas
- Increased ventilation in the individual's home
Describe Chalara ash dieback
- Caused by a fungus that infects ash trees
- Spread via airborne spores which are carried by the wind
- Causes dark lesions on bark and blackened leaves which wilt and eventually die
How can the transmission of chalara ash dieback disease be reduced
Control the movement of ash trees
Kill infected plants
Replant with a different species
Describe Malaria 
- Caused by plasmodium protist
- Spread by mosquito vectors which pick up the plasmodium protist when feeding on the blood of an infected organism and transmit malaria to other organisms during feeding
- Flu-like symptoms, damage to red blood cells, liver damage
How can the incidence of malaria be reduced?
● Mosquito nets
● Insect repellant
● Cover arms and legs
Describe stomach ulcers 
- caused by helicobacter pylori bacterium
- transmitted orally by eating infected foods or drinking infected water
- symptoms: stomach pain, vomiting, nausea
How can the transmission of helicobacter pylori be reduced
● Access to clean water
● Improved hygiene
● Improved sanitation (sewage disposal etc.)
Describe Ebola 
- Caused by Ebola virus
- Spread by direct contact with infected body fluids e.g. blood, semen, saliva, mucus, vomit
- Symptoms: fever, diarrhoea, vomiting, internal bleeding
How can the transmission of Ebola be reduced
- Improved hygiene
- Isolating infected individuals
- Sterilisation of outbreak areas
Describe simply how viruses cause disease 
They enter host cells and replicate inside of them. The host cells rupture, releasing new viruses.
How do viruses differ from other microorganisms
Viruses are not living organisms. They do not reproduce and can only replicate inside a host cell.
By what two pathways do viruses replicate inside living cells?
lytic pathway and lysogenic pathway
Describe the lytic pathway
1. Virus binds to specific receptors on host cell
2. Virus injects its DNA into host cell and replicates its DNA using host cell machinery
3. New viral structures are produced and assembled
4. Host cell ruptures, releasing new viruses
Describe the lysogenic pathway
1. Virus binds to specific receptors on host cell
2. Viral DNA injected into host cell and becomes integrated into host cell genome
3. Viral DNA replicates each time the host cell divides. However, the cell remains normal.
4. Trigger causes the activation of viral DNA. It enters lytic pathway.
Describe HIV 
- Caused by human immunodeficiency virus
- Spread by direct contact with infected body fluids e.g. blood, semen, breast milk.
- Destroys white blood cells making the individual immunodeficient and increasingly susceptible to other diseases.
- Leads to AIDS.
How can the spread of HIV be reduced
● Use of condoms and protected sex
● Needle exchange
● Screening blood for HIV
● Deterring infected mothers from breastfeeding
Describe chlamydia 
- Caused by Chlamydia bacterium
- Spread through sexual contact or direct contact with infected genital fluids
- Can result in infertility
How can the transmission of chlamydia be reduced
Use of condoms and protected sex
Screening
Describe the physical defence system within plants
- Waterproof waxy cuticle - surface barrier preventing the entry of pathogens
- Cellulose cell wall - further barrier against pathogens
Give some examples of chemical barriers in plants
- Secretion of toxins to reduce damage by pests e.g. stinging nettles
- Production of antibacterial chemicals that kill bacterial pathogens
Why are chemicals produced by plants useful
They produce physiological effects on the body so can be used in medicines to treat disease.
Give an example of a medicine derived from plants
- Quinine - antimalarial, bark of Cinchona sp.
- Aspirin - painkiller, bark/leaves of Salix alba
Why are plant defence systems important?
- Plants are producers so all organisms higher up in food chains rely upon their survival and ability to fight disease
- Important in maintaining human food security
How can plant diseases be detected and identified in the field
- Observation of symptoms e.g. Chalara ash dieback disease causes bark lesions. Books and online resources aid identification
- Analysis of the distribution of infected plants can indicate the type of pathogen involved and its mode of transmission e.g. airborne
- Changing environmental conditions to eliminate other causes such as nutrient deficiencies or water-logged soils
Why is it difficult to identify a disease using symptoms alone
Many diseases may have similar symptoms
How can plant diseases be detected and identified in the lab
- Detection of foreign antigens in a sample of plant tissue using monoclonal antibodies
- Analysis of DNA to identify any pathogen DNA in a tissue sample
What is a non-specific defence
- Always present
- Same for all organisms
- Prevents pathogens from entering the body
Give some examples of the body's physical defence system
Skin
Blood clotting
Respiratory tract
Give some examples of the body's chemical defence system
Tears
Hydrochloric acid in the stomach
What is the immune system?
The body's defense against disease causing organisms, malfunctioning cells, and foreign particles