B2 – Keeping healthy
What you already know: This topic builds on work you covered in year 8 with diseases
associated with topics relating to breathing & digestive systems
Key ideas: You will develop the following key ideas in this topic. At the start and the end of the
topic RAG the statements. Use this to help guide your revision.
RAG
Lesson Key Idea RAG end
start
Know the range of pathogens that cause diseases, how
1
symptoms are caused & rate of bacterial reproduction
Know how plants and animals defend themselves against diseases
2
in a non-specific way
Know & understand how the human immune system defends
3
against disease
4 Prevention of spread of diseases in animals & plants
5 What methods are used to determine the causes of infection
To know a range of microbiological techniques used in culturing
6
organisms
To know how to quantify the relative effectiveness of different
7
antibiotics
8 Production and use of monoclonal antibodies
Non infectious diseases-their causes & control including
9
cardiovascular & smoking related conditions.
10 Know the causes, prevention & treatments of CHD.
Be able to interpret graphs via identification of patterns &
11
suggest reasons for them.
Know examples of interacting diseases, know about bacterial
12 resistance to antibiotics & stages required for development of
medicinal drugs
Highlighted topics are triple only
,Lesson 1: Pathogens that cause diseases, how symptoms are caused
& rate of bacterial reproduction.
Pathogens are micro-organisms that cause disease. There can be many types of pathogens including
bacteria, viruses, protists or fungi. The diseases caused by pathogens are known as communicable
diseases as they can be spread between individuals. Pathogens can be spread in different ways.
Some pathogens can be spread through the air by coughing, sneezing and even talking (droplet
infection). Examples include flu (caused by a virus) and tuberculosis (caused by a bacteria). Some
pathogens are spread by direct contact. For example, sexually transmitted diseases such as
gonorrhoea (caused by a bacteria) and HIV/AIDS (caused by a virus). Other pathogens can be
spread through water, for example, cholera or salmonella. These diseases often cause diarrhoea.
Diseases often spread quicker through crowded city centres.
Task 2: Comprehension questions – each question should be attempted first from memory.
Every five questions get your green pen and use the text to check your answers.
1. Name four pathogens
2. Diseases can spread through the air, through
water, or through direct contact. Give an
example of a disease that spreads through air.
3. Give an example of a disease that spreads
through water.
4. Give an example of a disease that spreads
through direct contact
5. Why do diseases often spread quicker in cities?
The two main types of pathogens that cause
disease are bacteria and viruses. Bacterial
pathogens are prokaryotic cells that cause disease
by releasing toxins that make you feel ill. Once
inside our body bacteria cells divide by binary
fission. Viruses invade our cells, they then reproduce inside the cells (not by binary fission) and
continue to do so until the cell bursts. This can create direct symptoms, or you might experience
symptoms as a result of your immune system fighting off the infection. Because they are unable to
reproduce on their own viruses are not living things. They are also incredibly small, about 100 times
smaller than bacteria.
Task 3: Comprehension questions – each question should be attempted first from memory.
Every five questions get your green pen and use the text to check your answers.
6. What is a pathogen?
7. Which two pathogens are the most common causes of communicable disease?
8. Bacteria are often too small to see under a microscope. Can viruses be seen under a
microscope? Explain your answer.
9. Why are viruses not considered living things?
10. What do bacteria release that make you feel ill?
Task 3: Application questions – use your notes from this section and past sections to answer the
questions below, but you should try from memory first.
1. Clive says “Bacteria and Viruses are both
prokaryotic cells” explain the common
mistake he has made
2. List the different types of pathogens
3. State two diseases caused by bacteria
4. State two diseases caused by viruses
5. What are three ways pathogens can be spread
6. What do bacteria release to make us ill?
7. How do bacteria divide?
8. Draw and label the prokaryotic cell:
, 9. How do viruses make us ill?
10. Suggest a way that a pathogen could enter your body
11. Suggest why pathogens/diseases that spread through water often cause diarrhoea
12. Suggest ways that the spread of diseases in air droplets could be prevented
Task 4: Sophisticated Sentences
13. Complete the sentence starters below in your exercise book. Each one is about comparing
bacteria and viruses.
Both viruses and bacteria are examples of…
An example of a viral disease is…. Whereas….
Bacteria make us feel …. Similarly…..
Bacteria work by releasing…. Contrastingly….
14. Describe how diseases can be spread
15. A person becomes infected with bacteria. After one hour, there are 1000 bacteria present
in their body. After four hours, there are 250000 bacteria. Calculate the percentage change
in bacteria.
16. The school wants to bring in a rule where students must shake a teacher’s hand before
entering the classroom. Explain why this might be a bad idea.
Fungal diseases
Fungi are living organisms. They are Eukaryotic organisms and include: mushrooms, toadstools,
moulds and yeast. They produce spores (for reproduction) and digest organic matter. They do not
photosynthesise so in some ways are more closely linked to animals than plants.
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.
Protist diseases
Protists are microscopic and unicellular. They are Eukaryotes. The parasitic diseases that
they cause can be life threatening. Malaria is an example of a disease caused by a protist.
The parasite spends some of its time living inside mosquitoes and the rest inside humans. The
mosquito spread the protists from one human to another.
They are said to be the vector of transmission for the
disease. The vector is the organism that carries the
disease.
When in the body the protist can damage the liver and
the red blood cells. Malaria is widespread in tropical
areas and kills 660,000 people per year. Treatment for
malaria involves taking a combination of drugs and is
becoming less effective. The best strategies involve
preventing the spread by targeting the mosquito vectors.
This is achieved by:
✓ Using insecticide-impregnated insect nets to prevent human being bitten
✓ Using insecticides to kill mosquitoes
✓ Preventing the breeding of mosquitoes by removing their breeding habitats like
standing water.
✓ Providing travellers with antimalaria drugs which kill the parasites if they get bitten
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