B3

Question 1

Infections are caused when_____

Answer 1

A foreign pathogen invades an organism

Question 2

Types of pathogens

Answer 2

• Viruses
• Bacteria
• Fungi
• Protists

Question 3

Viruses

Answer 3

-tiny, non-living
-can reproduce rapidly
-they invade host cells and use them to make new virus articles
once the new viruses are made, they cause the cell to burst
-the cell damage is what makes us feel ill

Question 4

Bacteria

Answer 4

• small, living cells
• produce toxins(poisons) that make us feel ill
• can reproduce rapidly

Question 5

Fungi

Answer 5

• single-celled organism made up of hyphae(thread-like structures
• these hyphae’s grow and penetrate tissues
• they produce spores that can spread to other animals/plants

Question 6

Protists

Answer 6

• single celled eukaryotic organisms
• many are parasites
• they are often transferred to the host organism by a vector such as a mosquito or insect
• they damage tissues which make us feel illl

Question 7

Ways to spread diseases

Answer 7

• direct contact
• air
• water

Question 8

Ways to prevent diseases

Answer 8

Destroying vectors
-by killing insects are destroying habitats

Isolation
-isolate infected individuals to stop it spreading

Hygiene
-destroy pathogens by washing them away

Vaccination
-make people immune to infection

Question 9

Virus examples

Answer 9

Measles

• symptoms: fever, red skin rash
• can be fatal
• most people are vaccinated against it
• spread by breathing in droplets from sneezes/coughs

TMV(tobacco mosaic virus)

• affects plants such as tomatoes
• causes a mosaic pattern(discolouration)
• photosynthesis cant take place so plants growth is affected

HIV

• spread by sexual contact or exchange of bodily fluids(eg. through needles)
• symptoms= starts as flu then can cause AIDS

Question 10

Bacteria examples

Answer 10

Gonorrhoea

• sexually transmitted
• symptoms: pain when urinating, thick yellow/green discharge
• prevented through sing contraception such as condoms

Salmonella

• causes food poisoning
• the bacteria release toxins that cause fever, stomach pain, vomiting and diarrhoea

Question 11

Fungi example

Answer 11

Rose black spot

• can be spread through environment in water or air
• causes purple or black spots on leaves of rose plants
• leaves discolour and fall off, preventing photosynthesis
• treated by destroying/removing affected leaves

Question 12

Protist example

Answer 12

Malaria

• spread by the female mosquito(a vector)
• the mosquito carries malaria and transfers the infection into a persons bloodstream when it bites them
• causing fevers, which can be fatal

Question 13

Fighting diseases

-Non specific defences

Answer 13

Mucus
-traps the bacteria entering our airways

Tears
-contain enzymes that destroy pathogens

Stomach
-produces hydrochloric acid which destroys pathogens

Skin
-waterproof barrier that pathogens cannot pass through

Question 14

Fighting diseases

-Immune system

Answer 14

1) consuming them
- A white blood cell finds the pathogen and engulfs it by changing shape
- The white blood cell absorbs and digests the pathogen, destroying it. This is called phagocytosis.

2) Producing antibodies
- White blood cells recognise foreign antigens on the surface of pathogens and produce antibodies
- Antibodies are specific to a particular pathogen

3) Producing antitoxins
- These counteract toxins produces by the invading bacteria

Question 15

How does vaccination work?

Answer 15

1. inject dead pathogen
2. white blood cells recognise the foreign antigen and produce antibodies
3. some of the white blood cells remain in the blood as memory cells. If the same pathogen invades again it can produce antibodies faster.

Question 16

Pros/Cons of vaccination

Answer 16

Pros: help control diseases, large outbreaks of diseases can be prevented

Cons: don’t always work, can cause bad reactions

Question 17

What do antibiotics do?

Answer 17

Antibiotics such as Penecillin kill bacteria

Question 18

What can happen to bacteria?

How to stop resistance?

Answer 18

Bacteria can become resistant to antibiotics meaning they can’t be killed.

• only prescribe if needed
• patients should complete full course to ensure all bacteria are killed

Question 19

What is the ‘superbug’ called? and why is it referred to as the ‘superbug’?

Answer 19

MRSA

because its resistant to many antibiotics

Question 20

New drugs need to be tested for_____

Answer 20

Toxicity
-how much can be taken before side effects are too bad

Efficiency
-how well it works

Dose
-how much do you need to take

Question 21

Drugs from plants

Answer 21

Aspirin from willow bark

Digitalis from fox glove flowers. These are a heart drug.

Question 22

Penicillin is used to____

Answer 22

stop bacteria growth

Question 23

Drug testing

Answer 23

1. The drugs are tested on cells grown in the laboratory. This allows the efficacy and possible side effects to be tested.
2. Drugs that pass the first stage are tested on animals in the second part of a drug trial.
3. Drugs that have passed animal tests are used in human clinical trials. They are tested on healthy volunteers to check that they are safe. The substances are then tested on people with the illness to ensure that they are safe and that they work. Low doses of the drug are used initially, and if this is safe the dosage increases until the optimum dosage is identified.