Year 9 Biology
Micro-organisms and Disease
Year 9 Biology
Task 1: Notes• A disease is anything
that causes your body to stop working properly
• One cause of disease is bacterial infection.
• Bacteria are a type of micro-organism
Year 9 BiologyMicro-organisms
• Micro organisms are the tiny living things that can only be seen using a microscope.
• They are everywhere, including the food you eat and you!
Year 9 BiologyIgnaz Semmelweiss
• Ignaz Semmelweiss was a doctor in the mid 1800s• He wondered why so many women died of ‘childbed fever’
soon after giving birth. • He also noticed that student doctors carrying out work on dead
bodies did not wash their hands before delivering a baby.
• When he got them to wash their hands in calcium chloride solution before delivering babies, fewer women died.
• He concluded that something was carried by the doctors from the dead bodies to the women.
Year 9 BiologyDoctors / Scientists Pasteur
and Lister• Pasteur proved that there
were ‘germs’ in the air and that they carried infection and disease.
• Lister developed a special soap called carbolic soap.
• He insisted that all medical instruments, dressings and even surgeons should be cleaned with it before any operation.
• Lister’s patients stayed healthy.Chemicals that are used to clean wounds or get rid
of sores are called antiseptics.
Year 9 Biology
• Why is it important to keep them clean?
• What is an antiseptic / disinfectant?
• What is now used on wards for visitors? Why?
Task 2: Hospitals
Year 9 Biology
Bacteria• Bacteria are examples of
decomposers that convert dead plant and animal matter into nutrients that make plants grow
• In some animals bacteria can help with digestion
• Bacteria that cause disease are called pathogens
• Infectious diseases are diseases that can spread.
Year 9 BiologyTask 3: microbes
• List the 3 main types of microbe and a disease they cause
• Bacteria (cause cholera, boils, MRSA, typhoid, tuberculosis)
• Viruses (cause warts, herpes, polio, flu, mumps, measles, smallpox)
• Fungi (cause athlete’s foot, ringworm)
A disease causing organism is called a pathogen
Year 9 Biology
Questions1. What is a disease?2. What are the main causes of
disease?3. What is a decomposer?4. What is a pathogen?5. What does infectious mean?
Year 9 Biology
First line of defence• skin• fluids• hairs in nose• Acid in stomach• vomiting/diarhoea
Year 9 Biology
Second line of defence• Neutrophils (large WBC) consuming
bacteria causing pus• Lymphocytes and macrophages
(other WBC) are release from lymph nodes
• Macrophages engulf/destroy bacteria• Lymphocytes make antibodies that
provide future protection.
Year 9 Biology
Year 9 BiologyMicro-organisms also have
enzymes• Temperature is
increased during an infection so pathogens cannot function as efficiently
Year 9 BiologySummary task
• The _______ which cause infectious diseases are known as ________• Once __________ and __________ get inside your body they _________
rapidly.• They ________ your tissues and may produce _______ of disease.• Bodys first line of defence include _________• Lymphocytes produce _________. Macrophages _______ pathogens.
A __________ can also reduce the activity of a pathogen.
Skin Toxins temperature viruses acid engulfmicro organisms reproduce pathogens
Antibodies damage symptoms bacteria