GCSE AQA Biology - Topic 3 - INFECTION AND RESPONSE Flashcards
What are pathogens?
Microorganisms that enter the body and cause disease
What type of diseases do pathogens cause?
Communicable (infections) diseases, that can easily spread
What can pathogens affect?
Both plants and animals
What are bacteria?
Very small cells which can reproduce rapidly inside your body
What can bacteria do?
Make you feel ill by producing toxins that damage your cells and tissues
What are viruses?
They are not cells, they’re tiny 1/100th the size of bacterium and they reproduce rapidly inside your body
What do viruses do?
Live inside your cells and replicate themselves using the cells machinery to produce many copies of themselves, this cell will then burst releasing all the new viruses
What about a virus makes you feel ill?
The cell damge
What are protists?
They are mostly single-celled eukaryotes, some are parasites, they are often transferred to the organism through a vector
What is a parasite?
They live in or on other organisms and can cause them damage
What is a vector?
An insect that carries the protist
What can fungi be?
Single-celled or have a body which is made up of hyphae
What are hyphae?
Thread-like structures
What do hyphae do?
Grow and penetrate human skin and the surface of plants, causing diseases
What three ways can pathogens be spread?
Water, Air, Direct Contact
How are pathogens spread through water?
They can be picked up by drinking or bathing in dirty water e.g. cholera
What is cholera?
A bacterial infection that’s spread by drinking water contaminated with diarrhoea of other sufferers
How are pathogens spread by air?
They can be carried in the air and then breathed in, some air born pathogens are carried in the air by droplets produced when you cough or sneeze
What is an example of a pathogen spread by air?
The influenza virus
How are pathogens spread by direct contact?
They can be picked up by touching contaminated surfaces, including the skin e.g. athletes foot
What is athletes foot?
A fungus which makes the skin itch and flake off, it is most commonly spread by touching the same thing as the infected person e.g. shower floors or towels
What are the three viral diseases you need to know about?
Measles, HIV, and Tobacco mosaic virus (TMV)
How is measles spread?
Through droplets of an infected persons cough or sneeze
What do people with measles develop?
A red skin rash and a sign of a fever
What can happen if there are complications with measles?
It can be very serious or even fatal, for example it can sometimes lead to pneumonia or a brain infection called encephalitis
When are most people vaccinated against measles?
When they are young
What is HIV?
A virus spread by sexual contact or exchanging bodily fluids such as blood, this can happen when people share needles when taking drugs
What are the symptoms of HIV?
Initially flu-like symptoms for weeks, usually the person doesn’t experience any symptoms for several years
What can HIV be controlled?
Through antiretroviral drugs which stop the virus replicating
What does the HIV virus do?
Attack immune cells, if the body’s immune system is badly damaged, it can’t cope with other infections or cancers.
What is the stage in HIV when your immune system is severely damaged?
Late stage HIV infection or AIDS
What is tobacco mosaic virus (TMV)?
A virus that affects the growth of many species of plants e.g. tomatoes
What does TMV cause?
A mosaic pattern on the leaves of plants, parts of it become discoloured. This means that the plants can’t carry out photosynthesis very well
What is a fungal disease that you need to know?
Rose black spot
What is rose black spot?
A fungus that causes black or purple spots to develop on the leaves of rose plants, the leaves can then turn yellow and drop off, this means less photosynthesis can happen
How does black rose spot spread?
Through the environment e.g. water or wind
How can gardeners treat black rose spot?
Using fungicides and by stripping the plant of its affected leaves, the leaves then need to be destroyed so that fungus can’t spread to other rose plants
What is a disease caused by a protist?
Malaria
Where does part of malarial protist’s life take place?
Inside a mosquito, they are vectors. They pick up the malarial protist when feeding on other infected animals
What happens every time the vector mosquito feeds on another animal?
It passes the malarial disease onto that animal by inserting the protist into the animals bloodstream
What does malaria cause?
Repeating episodes of fever and can be fatal
How can the spread of malaria be reduced?
Reducing mosquitos ability to breed, insecticides and mosquito nets