Pathogens and diseases Flashcards
How do viruses make you ill?
The damage the cells in which they reproduces.
How do bacteria make you ill?
They reproduce and release toxins
How does the body protect itself against the entry of pathogens
Mucus in our airways traps bacteria and viruses breathed in.
Blood produces scabs to seal wounds so pathogens cannot enter.
Stomach contains hydrochloric acid to kill most bacteria and viruses.
Skin is a waterproof barrier -this stops pathogens entering the body.
What is a pathogen ?
This is a bacterium or virus that causes disease.
White blood cells are part of the immune system. How do they defend the body?
- They can ingest pathogens. This means they digest and destroy them.
- They produce antibodies to help destroy particular pathogens.
- They produce antitoxins to counteract the toxins that pathogens produce.
What is an antibiotic?
This is a drug that kills bacteria inside the body.
Why can’t you use an antibiotic to treat flu?
Flu is caused by a virus. Antibiotics do not kill viruses because they’re not ‘living’ and they also reproduce inside the cells.
Name an antibiotic
Penicillin
Explain how bacteria have developed resistance to antibiotics.
- There is a variation in the population of bacteria due to mutation in their genes.
- Some bacteria are more resistant to antibiotics than others.
- If an antibiotic is used only for a short time,only the least resistant bacteria die; the most resistant survive.
- Surviving bacteria breed and pass on their genes for resistance in antibiotics to their offspring.
- Over many generations you end up with a strain of bacteria that are resistant to antibiotics.
What is an antibiotic?
A drug that destroys bacteria inside the body without damaging human cells.
Who discovered penicillin the antibiotic?
Alexander Fleming 1928
Why are viruses difficult to kill?
They reproduce inside the body cells so any treatment could also damage the body cells.
How do antibiotics work?
Antibiotics kill bacteria inside your body.
Why do some pathogens spread rapidly?
Because very little people are immune to the new pathogen.
How does natural selection cause resistant populations of bacteria to develop?
The antibiotics kill the non resistant strains which allows the resistant ones to survive and multiply.
How would you set up a culture bacteria in a school lab?
Use sterile Petri dish and agar
Sterilise inoculating loop heat it red hot and let cool
Inoculate agar with zigzag streaks of bacteria using sterile loop.
Replace the lid on the dish quickly to avoid contamination.
Secure lid with tape but do not steal
Label culture and incubate no warmer that 25 degrees c.
How do viruses differ from bacteria?
Viruses are smaller than bacteria.
How do pathogens make you feel I’ll?
They reproduce rapidly inside your body and damage your cells. They also produce toxins that make you feel unwell.
What are the four main ways in which infectious diseases are spread?
Droplet infection, contaminated food, through a break in the skin , direct contact.
What are the three main ways in which your body prevents pathogens getting in?
Skin acts as a barrier, breathing organs trap mucus, acid in the stomach, blood clots to seal wounds.
Why don’t medicines like aspirin actually cure your illness?
They only get rid of the pain, they do not kill the pathogens that are making you I’ll.
What is an antibiotic?
A drug that kills pathogenic bacteria in your body
How do antibiotics work?
They damage bacterial cells without damaging human cells
What is agar jelly?
A nutrient- rich medium used to culture microorganisms such as fungi and bacteria.
