Infection and response

What are communicable diseases

• disease that can be passed from person to person

  transmitted:

  • through the air

  • Contaminated food and water

  • Direct contact

What microorganisms cause communicable disease

• bacteria

• Fungi

• Viruses

• Protists

What are pathogens

Microorganisms that cause disease

How do you prevent the spread of communicable diseases

have to stop it spreading in the first place by:

• hygiene → washing hands, cleaning cookery items

• Vaccination → can’t catch or pass on disease

• Killing vectors → use insecticides

• Iscolate / quarantine → prevents contact so disease can’t spread

What are viruses

Viruses damage our cells by entering them and can burst the cell, damaging our body

• organisms that are not living and not cells

• 10,000 x smaller than animal cells

• Can’t reproduce on their own

How do viruses cause disease

Invade and reproduced inside living body cells, leading to damage

What is measles

• Virus

• spread by droplets

• Symptoms are red rash and fever → can be fatal

• Prevented by vaccinations

What is human immunodeficiency virus

• Virus

• also known as HIV

• Spread by exchanging bodily fluids → sharing needles or sexual contact

• Flu like symptoms till the immune system becomes so weak or develops infections (AIDS)

• Can be treated with antiretroviral drugs → prevent virus replicating but must be used early on in disease

What is tobacco mosaic virus (TMV)

• Virus

• occurs in tobacco and tomato plants

• Symptoms are mosaic pattern on leaf → discoloured and therefore photosynthesis can’t take place properly on these patches, meaning it can’t produce enough sugars for proper growth

What is bacteria

• single celled organisms → reproduce themselves, often inside our body

• 100x smaller than human cells

• Produce toxins

• Lots of bacteria in small intestines to break down food

How does bacteria cause disease

Once in the gist they divide rapidly by binary fission. They reproduce toxins that damage cell tissue

What is salmonella

• bacteria

• Caused by contaminated food

• Symptoms are fever, stomach cramps, vomiting and distracted

• Goes away by itself over a short period of time

• Prevented by vaccinating chickens in uk

What is gonorrhoea

• passed by sexual contact

• Symptoms are pain when urinating, and yellow/ green discharge

• Prevented by avoiding unsafe sex and using contraception

• Penicillin was used as treatment however many strains of gonorrhoea have become resistant. We now have to use rarer, more expensive antibiotics

What is fungi

A eukaryotic cell that is either multicellular or unicellular

• yeast is unicellular

• A mushroom is multicellular

What do multicellular fungi contain, what does this do

Contains hyphae

• can penetrate the skin

• Produces spores → can spread easily

Rose black spot

• fungal disease

• Symptoms are purple or black spots forming on the leaves of plants → especially roses

  This causes leaves to turn yellow / discolour and drop off as the leaves cannot photosynthesis as there’s not enough chlorophyll so reduces growth

• Is spreads by water or wind

• To treat it you must chop off and destroy leaves so the fungi doesn’t spread and spray with fungicides

What are parasites

• They live in or on another organism.

• Transported by a vector → other organisms that transport protists between hosts and do not catch the disease themselves

What is malaria

• parasitic protist → means it needs a host to survive. That host is a mosquito

  e.g when a mosquito sucks on an infected animals blood, it shocks up the parasite. When the mosquito goes to bite the next person, that person will become infected

• Symptoms are fever and headache. There can be recurrent episodes and be fatal

What do physical and chemical barriers do

Stop the pathogen from entering

What do the skin do

• acts as a physical barrier

• Secretes oils and anti microbial substances → these kill pathogens