Which of these lists contains only types of pathogen?
- Viruses, bacteria, protists and fungi
- Viruses, bacteria, enzymes and fungi
- Bacteria, protists, antibodies and fungi
- Viruses, protists, antitoxins and bacteria
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Answer: A A (1)
Describe three ways in which pathogens can be spread.
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- by direct contact (1) allow example, e.g. sexual contact / exchange of body fluids
- by water (1)
- by air (1) allow droplets from coughs and sneezes
State two symptoms of measles and describe how the measles virus is spread.
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- fever (1)
- red skin rash (1)
- inhalation of droplets from sneezes and coughs (1) allow breathing in droplets
HIV can lead to AIDS. (a) Describe how HIV is spread. (2) (b) Explain how HIV infection can lead to AIDS. (2)
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- sexual contact (1)
- exchange of body fluids / blood (1) allow sharing needles by drug users
- HIV attacks the body's immune cells (1) allow white blood cells
- (late stage infection / AIDS) immune system so badly damaged that it cannot deal with other infections or cancers (1)
- do not accept 'HIV is cured / killed by antiretroviral drugs'
Tomato plants infected with tobacco mosaic virus (TMV) have leaves with a mosaic pattern and the plants grow slowly. Explain why the plants grow slowly.
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- leaves discoloured / mosaic pattern so less photosynthesis (1)
- less glucose / food made for growth (1)
- ignore 'less chlorophyll' unless linked to photosynthesis
Salmonella food poisoning is caused by bacteria. (a) Describe how people become infected with Salmonella. (1) (b) State two symptoms. (2)
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- (a) bacteria ingested in food / food prepared in unhygienic conditions (1)
- (b) fever (1)
- (b) abdominal cramps (1)
- (b) vomiting (1)
- (b) diarrhoea (1)
- Max 3 (max 2 for (b))
Gonorrhoea is a sexually transmitted disease. (a) Describe two symptoms of gonorrhoea. (2) (b) Give one way the spread of gonorrhoea can be controlled. (1)
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- thick yellow or green discharge (from vagina or penis) (1)
- pain on urinating (1)
- treatment with antibiotics / using a barrier method of contraception, e.g. condom (1)
Rose black spot is a fungal disease. (a) Describe the symptoms of rose black spot. (1) (b) Describe two ways of treating rose black spot. (2)
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- purple or black spots on leaves (1) allow leaves turn yellow and drop early
- using fungicides (1)
- removing and destroying affected leaves (1)
Malaria is caused by a protist. (a) Explain how malaria is spread from one person to another. (2) (b) Describe two ways the spread of malaria can be controlled. (2)
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- mosquito is the vector / carries the pathogen (1)
- mosquito picks up the protist from an infected person and passes it on when it bites another person (1)
- preventing the mosquitos from breeding (1)
- using mosquito nets to avoid being bitten (1)
Which of these is one of the body's non-specific defences against pathogens?
- Antibody production
- Antitoxin production
- Acid in the stomach
- Vaccination
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Answer: C C (1) (stomach acid kills pathogens; A and B are white blood cell responses to a particular pathogen or toxin; D is a medical intervention, not a natural body defence)
Describe how the skin, the nose, the trachea and bronchi and the stomach each help to defend the body against pathogens.
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- skin acts as a barrier (to pathogens) (1) allow secretes substances that kill pathogens
- nose: hairs / mucus trap pathogens (1)
- trachea and bronchi: mucus traps pathogens (and cilia move it away) (1)
- stomach: (hydrochloric) acid kills pathogens (1)
Describe three ways in which white blood cells help to defend the body against pathogens.
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- phagocytosis / engulf and digest pathogens (1)
- antibody production (1) allow antibodies destroy / target specific pathogens
- antitoxin production (1) allow antitoxins neutralise toxins
- do not accept 'kill pathogens' without a method
Explain how vaccination prevents a person from becoming ill with a disease.
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- vaccine contains dead / inactive form of the pathogen (1)
- stimulates white blood cells to produce antibodies (1)
- if same pathogen re-enters the body, white blood cells respond quickly (1)
- produce the correct antibodies (1) so infection prevented / pathogen destroyed
- do not accept 'vaccine contains antibodies' or 'live pathogen'
A town has 15 000 people. 12 600 people have been vaccinated against measles. Calculate the percentage of the population that is vaccinated.
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- 12 600 ÷ 15 000 × 100 (1)
- = 84% (1) correct answer with or without working gets 2 marks
Explain how vaccinating a large proportion of a population can protect people who have not been vaccinated.
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- most people are immune so the pathogen cannot spread easily (1)
- unvaccinated people are less likely to come into contact with someone who is infected (1)
A patient has influenza, which is caused by a virus. The doctor decides not to prescribe an antibiotic. Explain why.
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- antibiotics cannot kill viruses / viral pathogens (1) allow antibiotics only kill bacteria
- so the antibiotic would not cure the disease (1)
- viruses live and reproduce inside cells (1)
- difficult to kill viruses without damaging the body's tissues (1)
- Max 3
Name the plant or microorganism that each of these drugs originates from. (a) digitalis (1) (b) aspirin (1) (c) penicillin (1)
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- foxgloves (1)
- willow (1)
- Penicillium mould (1) allow Penicillium
A new drug has been developed. Describe how preclinical testing and clinical trials are used to test the drug.
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- preclinical testing is done in a laboratory (1)
- using cells, tissues and live animals (1)
- clinical trials use healthy volunteers and patients (1)
- very low doses given at the start (1)
- if safe, further trials to find the optimum dose (1)
- Max 4
Describe the process of discovery and development of a new medicine. Include preclinical testing, clinical trials and what happens to the results.
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| Level | Marks | What the answer does |
|---|---|---|
| 3 | 5–6 | A clear, detailed and logical description that covers where drugs come from, preclinical testing, clinical trials including dose and placebo, and peer review. Correct scientific terms are used. |
| 2 | 3–4 | A description that covers most stages in a sensible order but with some gaps or a lack of detail about what each stage tests. |
| 1 | 1–2 | A few simple, separate points about testing a drug, with little detail or order. |
Indicative content
- drugs may be extracted from plants or microorganisms or synthesised by chemists in the pharmaceutical industry
- new drugs must be tested to check they are safe and effective
- tested for toxicity, efficacy and dose
- preclinical testing in a laboratory using cells, tissues and live animals
- clinical trials use healthy volunteers and patients
- very low doses given first; if safe, further trials to find the optimum dose
- double blind trials: some patients given a placebo
- results published only after peer review