1
Q
How are diseases caused by viruses,bacteria,protists and fungi are spread in animals and plants?
A
- Pathogens can be viruses, bacteria, protists or fungi.
- They may infect plants or animals and can be spread by direct contact, by water or by air
- Bacteria and viruses may reproduce rapidly inside the body
2
Q
How can the spread of diseases be reduced or prevented?
A
- Wash and dry your hands regularly and well
- Stay at home if you are sick
- Cover coughs and sneezes
- Clean surfaces regularly
3
Q
What does bacteria produce and do to our body?
A
Produce poisons(toxins) that damage tissues which make us feel ill
4
Q
What do viruses do to our body?
A
Viruses live and reproduce inside cells, causing cell damage
5
Q
What is measles?
A
- Measles is a viral disease showing symptoms of fever and a red skin rash.
- Is a serious illness that can be fatal if complications arise.
- For this reason most young children are vaccinated against measles.
- The measles virus is spread by inhalation of droplets from sneezes and coughs.
6
Q
What is HIV?
A
- HIV initially causes a flu-like illness
- Unless successfully controlled with antiretroviral drugs the virus attacks the body’s immune cells
- Late stage HIV infection, or AIDS, occurs when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers
- HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles
7
Q
What is Tobacco Mosaic Virus (TMV)?
A
- Tobacco mosaic virus (TV) is a widespread plant pathogen affecting many species of plants including tomatoes.
- It gives a distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis.
8
Q
What is salmonella?
A
- Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions.
- In the UK, poultry are vaccinated against salmonella to control the spread.
- Fever, abdominal cramps, vomiting and diarrhea are caused by the bacteria and the toxins they secrete.
9
Q
What is gonorrhoea?
A
- Gonorrhea is a sexually transmitted disease (STD) with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating.
- It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant strains appeared.
Gonorrhea is spread by sexual contact. - The spread can be controlled by treatment with antibiotics or the use of a barrier method of contraception such as a condom.
10
Q
What is rose black spot?
A
- Rose black spot is a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early
- It affects the growth of the plant as photosynthesis is reduced
- It is spread in the environment by water or wind
- Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves
11
Q
What is the pathogen that causes malaria?
A
Protists
12
Q
What is malaria?
A
- The malarial protist has a life cycle that includes the mosquito
- Malaria causes recurrent episodes of fever and can be fatal
- The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten.
13
Q
What are the non-specific defense systems of the human body?
A
- Skin
- Nose
- Trachea and bronchi
- Stomach
14
Q
How does skin defend itself against pathogens?
A
- The skin covers almost all parts of your body to prevent infection from pathogens
- If it is cut or grazed, it immediately begins to heal itself, often by forming a scab
- This prevents infection as the skin acts as a physical barrier
15
Q
How does the nose defend itself against pathogens?
A
- The nose has internal hairs, which act as a physical barrier to infection
- Cells in the nose produce mucus which traps pathogens before they can enter the lungs
- When the nose is blown, the mucus, and any pathogens that are trapped within it, is removed
16
Q
How does the trachea and bronchi defend itself against pathogens?
A
- Trachea runs from the larynx (voice box) to the bronchi.
- The cells that line the trachea have hairs called cilia, which are much smaller than those in the nose
- These are called ciliated cells
- The ciliated cells waft their hairs and move mucus and pathogens upwards towards the throat where they are swallowed into your stomach
17
Q
How do goblet cells defend themselves from pathogens
A
- Create the mucus in order to trap pathogens
- The production of mucus in your airways is a physical barrier
18
Q
How does the stomach defend itself against pathogens?
A
- Stomach acid does not break down food in the same way as enzymes.
- It is part of the body’s non-specific first line of defence. It contains hydrochloric acid, and while it does us no harm, it is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water.
- Stomach acid is a chemical barrier against infection.
19
Q
If a pathogen enters the body what does the immune system do?
A
The immune system tries to destroy the pathogen
20
Q
How can white blood cells help defend against pathogens?
A
- Phagocytosis
- Antibody production
- Antitoxin production
21
Q
How does vaccination prevent illness in an individual?
A
- A vaccination basically injects an inactive form of a pathogen into the body
- This will activate an immune response and antibody production, which means that memory cells are made
- This protects the individual in case the real pathogen enters the blood again
- Vaccinations use inactive or dead pathogens
22
Q
How is the spread of pathogens reduced by immunising a large proportion of the population?
A
- If enough of the population is vaccinated against a certain pathogen herd immunity is achieved because so many people are protected against it, it is unlikely the pathogen will enter a person who has not been immunised
- Very few people will be able to pass the pathogen onto others, preventing the spread of the pathogen, therefore protecting the population as a whole
23
Q
What are examples of medicines in treating disease?
A
- Antibiotics
- Painkillers
- Drugs
24
Q
What is antibiotics used for?
A
- Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body.
- It is important that specific bacteria should be treated by specific antibiotics
- The use of antibiotics has greatly reduced deaths from infectious bacterial diseases
25
What is painkillers used for?
- Painkillers are used to relieve symptoms.
- They do not get rid of infection. Examples include ibuprofen and paracetamol
- Painkillers help relieve pain or other symptoms but don't treat the cause
26
What is the benefit and drawback of antibiotics?
- The use of antibiotics has greatly reduces deaths from infectious bacterial diseases
- However, the emergence of strains resistant to antibiotics is of great concern
27
What can antibiotics not do?
Kill viral pathogens
28
What are painkillers and other medicines used to treat?
Symptoms of disease but do not kill the pathogens
29
When developing drugs what is it also difficult to do?
Kill viruses without also damaging the body's tissues
30
What was the process of discovery and development of new medicines? (Stage 1)
- The drugs are tested using computer models and skin cells grown using human stem cells in the laboratory
- This allows the efficacy and possible side effects to be tested. - Many substances fail this first test of a preclinical drug trial because they damage cells or do not seem to work
31
What happens in the preclinical drug trial? (Stage 2)
- Drugs that pass the first stage are tested on animals in the second part of a preclinical drug trial
- In the UK, new medicines have to undergo these tests. But it is illegal to test cosmetics and tobacco products on animals
- A typical test involves giving a known amount of the substance to the animals, then monitoring them carefully for any side-effects
32
What happens in the human clinical trials? (Stage 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.
33
What are new drugs extensively tested for?
- Toxicity
- Efficacy
- Dose
34
What are procedures they always follow?
- Very low doses of the drug are given at the start of the clinical trial
- If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug
- In double blind trials, some patients are given a placebo
35
Why are new medical drugs tested and trialled before usage?
To check they are safe and effective
