B3

Question 1

How are diseases caused by viruses,bacteria,protists and fungi are spread in animals and plants?

Answer 1

• 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

Question 2

How can the spread of diseases be reduced or prevented?

Answer 2

• Wash and dry your hands regularly and well
• Stay at home if you are sick
• Cover coughs and sneezes
• Clean surfaces regularly

Question 3

What does bacteria produce and do to our body?

Answer 3

Produce poisons(toxins) that damage tissues which make us feel ill

Question 4

What do viruses do to our body?

Answer 4

Viruses live and reproduce inside cells, causing cell damage

Question 5

What is measles?

Answer 5

• 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.

Question 6

What is HIV?

Answer 6

• 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

Question 7

What is Tobacco Mosaic Virus (TMV)?

Answer 7

• 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.

Question 8

What is salmonella?

Answer 8

• 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.

Question 9

What is gonorrhoea?

Answer 9

• 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.

Question 10

What is rose black spot?

Answer 10

• 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

Question 11

What is the pathogen that causes malaria?

Answer 11

Protists

Question 12

What is malaria?

Answer 12

• 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.

Question 13

What are the non-specific defense systems of the human body?

Answer 13

• Skin
• Nose
• Trachea and bronchi
• Stomach

Question 14

How does skin defend itself against pathogens?

Answer 14

• 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

Question 15

How does the nose defend itself against pathogens?

Answer 15

• 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

Question 16

How does the trachea and bronchi defend itself against pathogens?

Answer 16

• 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

Question 17

How do goblet cells defend themselves from pathogens

Answer 17

• Create the mucus in order to trap pathogens
• The production of mucus in your airways is a physical barrier

Question 18

How does the stomach defend itself against pathogens?

Answer 18

• 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.

Question 19

If a pathogen enters the body what does the immune system do?

Answer 19

The immune system tries to destroy the pathogen

Question 20

How can white blood cells help defend against pathogens?

Answer 20

• Phagocytosis
• Antibody production
• Antitoxin production

Question 21

How does vaccination prevent illness in an individual?

Answer 21

• 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

Question 22

How is the spread of pathogens reduced by immunising a large proportion of the population?

Answer 22

• 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

Question 23

What are examples of medicines in treating disease?

Answer 23

• Antibiotics
• Painkillers
• Drugs

Question 24

What is antibiotics used for?

Answer 24

• 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

Question 25

What is painkillers used for?

Answer 25

• 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

Question 26

What is the benefit and drawback of antibiotics?

Answer 26

• The use of antibiotics has greatly reduces deaths from infectious bacterial diseases
• However, the emergence of strains resistant to antibiotics is of great concern

Question 27

What can antibiotics not do?

Answer 27

Kill viral pathogens

Question 28

What are painkillers and other medicines used to treat?

Answer 28

Symptoms of disease but do not kill the pathogens

Question 29

When developing drugs what is it also difficult to do?

Answer 29

Kill viruses without also damaging the body’s tissues

Question 30

What was the process of discovery and development of new medicines? (Stage 1)

Answer 30

• 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

Question 31

What happens in the preclinical drug trial? (Stage 2)

Answer 31

• 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

Question 32

What happens in the human clinical trials? (Stage 3)

Answer 32

• 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.

Question 33

What are new drugs extensively tested for?

Answer 33

• Toxicity
• Efficacy
• Dose

Question 34

What are procedures they always follow?

Answer 34

• 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

Question 35

Why are new medical drugs tested and trialled before usage?

Answer 35

To check they are safe and effective