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