GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Curriculum Skills Resources• Micro-organisms• Measuring length and using
a scale• Investigating the factors that
affect the growth of yeast• Harmful micro-organisms• Useful micro-organisms
• Understanding the different types of micro-organisms
• Using a micrograph of an image to calculate scale
• Understanding the different harmful micro-organisms
• Understanding the different useful micro-organisms
• Worksheets• Hand lenses or Bio-viewers• Calculator • Ruler• 6 bottles• Yeast • Water• Balloons• Sugar • Measuring cup
Before the introduction of an effective vaccine, rotavirus
was the top cause of diarrhea-related
deaths in young children.
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Rotavirus: Computer–aided reconstruction of a rotavirus based on several electron micrographs
https://en.wikipedia.org/wiki/Virus
IntroductionOrganisms such as plant and animals can be seen with the naked eye.
Micro-organisms are also living things but cannot be seen with a naked eye. They need a microscope to be seen. These occur everywhere but are too small to be seen.
These micro-organisms are what make you sick.
Microbiology is the study of micro-organisms.
Types of micro-organismsMicro-organisms can only be seen under a microscope.
There are positive as well as negative effects outcomes of micro-organisms.
For example: • Harmful bacteria in the form of diseases. • Yeast used to make bread and other products.
There are four types 1. Viruses2. Bacteria3. Protists4. Fungi
1. Viruses• Viruses are microscopic and attack healthy cells of living
organisms.
• They are considered as non-living as they do not carry out essential life processes or use energy.
• They reproduce by using materials from the host cells that they have infected. During this process the host cell is destroyed.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
4. Fungi• Fungi are living.• Fungi can be unicellular yeast or multicellular
mushrooms.• Most fungi grow on their food source by forming
hyphae. These are spreading networks of branching filaments.
• These filaments secrete enzymes that digest food.• They absorb the predigested food.
A collage of five fungi (clockwise from top-left): a mushroom with a flat, red top with white-spots, and a white stem growing on the ground; a red cup-shaped fungus growing on wood; a stack of green and white moldy bread slices on a plate; a microscopic, spherical grey semitransparent cell, with a smaller spherical cell beside it; a microscopic view of an elongated cellular structure shaped like a microphone, attached to the larger end is a number of smaller roughly circular elements that collectively form a mass around it
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Cap
Gills
Spores
Hyphae
Stalk(Stipe)
UndergroundHyphae
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Activity 11. What is the study of micro-organisms called?
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Measuring length and using a scale Using hand lenses or micro viewers to examine small objects (such as bread mould, mushrooms, newsprint).
Take a small object, put it under the hand lens to magnify it. Draw a sketch of what it would look like.
Magnification is making an object bigger in order to see a microscopic object.
How to use scale to estimate the size of a micro-organismThis is a micrograph of bacteria.It is measured using nanometres (nm) and micrometres (um).1nm= 0,000001mm1um= 0,001mm
1. scale bar = 8mm2. length of the cell = 23mm3. 23—
8 = 2.875 x 200 =575 nm
What is a micrograph?A photograph of an object that is viewed under the microscope. This allows to see detail and to see what a micro-organism would look like up close.A scale bar is given with the image to work out the actual size.
https://en.wikipedia.org/wiki/Micrograph
Follow the steps to estimate the size of a micro-organism1. Measure the length of the scale bar in millimetres using a ruler.2. Measure the length of the organism in millimetres.3. Divide the length of the organism by the length of the scale bar. Multiply your answer by the length
printed on the scale bar.4. Add the unit of measurement of the scale bar to your answer.
Activity 21. Work out the length of the shown virus. Make sure to show all calculation.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Investigating the factors that affect the growth of yeast
Observing micro-organisms by investigating the growth of yeast under different conditions [use different amounts of sugar, different temperatures and record observations.
Background: Yeast is a fungus that uses simple sugars as a food source. The yeast breaks down sugar to release energy and gives off carbon dioxide.
Aim: To show that yeast is most active in certain conditions. It will grow quicker and produce more carbon dioxide.
Method: 1. Use six different bottles, each should have a capacity of
350ml or more and label them 1-5.2. Add one packet of yeast to each bottle as well as the
following amounts of sugara. No sugar.b. 15ml of sugar that has been stored at room
temperature.c. 25ml of sugar that has been stored at room
temperatured. 15ml of sugar that has been stored in the fridgee. 15ml of sugar that has been stored in a warm area.
3. Fill each bottle will 300ml of water and shake to dissolve the ingredients.
4. Remove the lid and place a deflated balloon over the opening of each bottle. Leave the bottles for one hour and observe the differences.
5. Remove the balloons and tie them closed, so that no air can escape.
6. Fill a measuring cup with a constant amount of water, submerge each balloon separately and measure to submerged amount. Subtract the submerged amount from the initial amount of water. Repeat this with each balloon.
7. Complete a table to collaborate the results.
Results: Yeast releases different amounts of carbon dioxide in different conditions.
Conclusion: Sugar and a warm area is the ideal condition for yeast to be active. Present your information in clear sections and complete detail.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Harmful micro-organisms There are micro-organisms that cause disease.
Robert Koch a German doctor discovered that micro-organisms can cause diseases.
Disease-causing organisms are found almost everywhere, such as at ATMs, handrails of staircases, and flush handles of toilets and door handles. Food and drink can also contain micro-organisms and these can also make you sick.
Some common diseases caused by micro-organisms include;
Tuberculosis• Tuberculosis (TB) is a bacterial infection that usually affects
the lungs. • TB is spread through the air when people with the infection
cough or sneeze.• The droplets of mucous and saliva containing bacteria float
in the air and are inhaled by other people. • A main symptom is a cough that lasts for a few weeks. • The person may cough up blood, have fever, weight loss and
night sweats. • An x-ray can confirm the presence of TB.• It is treated with a long course of antibiotics.
AIDS(Acquired immunodeficiency syndrome)• AIDS is a virus.• When it enters the body it infects and destroys the cells of
the immune system.• As the immune system is destroyed the body is unable to
fight off normal infections.
A person becomes infected with AIDS through the contact of bodily fluids of a person that is infected.
For example;• Sexual contact• Sharing needles• Contact with infected blood or transfusion of infected
blood transfer from mother to child during pregnancy or breastfeeding.
There is no cure for AIDS, but by taking antiretroviral (ARVs) and living a healthy lifestyle, the disease can be managed.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
What are the symptoms?• fever• swollen glands
• aching muscles• sore throat
These initial symptoms may disappear but you are still living with the virus that is killing your cells.
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Malaria• Malaria is caused by a parasite called plasmodium.• When a mosquito that is carrying the parasite bites you, it
injects the parasite into your blood.• The parasite travels to your liver where it lays eggs which
hatch into more parasites. • These travel into your red blood cells and start destroying them.
What are the symptoms?• high fever• chills• headaches
• vomiting• sweating• muscle aches
How can it be treated?It is best to prevent it from occurring by taking medicine before you go to an area that has Malaria. This medicine is called prophylactics. The medicine will kill any parasites that enter you blood if you become infected.
Waterborne diseases• A waterborne disease is an illnesses caused by drinking water
that has been contaminated with micro-organisms.• It causes severe diarrhoea and vomiting which can lead to
dehydration.• The micro-organisms include protozoa, parasites and bacteria. • Waterborne diseases such as cholera and e-coli account for
many child deaths in third world countries. Escherichia coli (E.coli) is a bacterium that occurs
naturally in your large intestines. However if e-coli is ingested it enters the stomach and small intestine where it causes severe cramps and diarrhoea. It also causes fever, nausea and vomiting.
Cholera is caused by Vibrio cholera (bacterium). It releases toxins that cause the intestines to release water which produces diarrhoea.
How does one get infected?One gets infected by eating foods that have been contaminated with faecal matter. Wash raw produce like fruit and vegetables thoroughly before it is eaten.
What is the treatment?It is treated with antibiotics and methods to stop dehydration.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Preventing infection with micro-organismsEffective methods of preventing the spread of diseases caused by micro-organisms include washing hands and sterilising.It is better to prevent than treat!
Method of prevention Image
Wash your hands with soap
Wash all fruit and vegetables
Cover your mouth when you cough or sneeze
Wear gloves when coming into contact with blood or bodily fluids
Boil water to kill any micro-organisms
Refrigerate food to prevent the rapid growth of micro-organisms
Modern scientists such as Louis Pasteur, Sir Alexander Fleming and Jonas Edward Salk play an important role in identifying and developing cures for some diseases.
Life expectancy has increased due to the development of vaccines and medicines.
Louis Pasteur’s pasteurisation experiment illustrates the fact that the spoilage of liquid was caused by particles in the air rather than the air itself. These experiments were important pieces of evidence supporting the idea of Germ Theory of Disease.
Pasteur’s research showed that drinking the liquid would make them ill and that heating it would kill the micro-organisms. This is known as pasteurisation and is used with milk and beer.
Beliefs about the causes of diseases Before the invention of the microscope, different cultures had their own beliefs about the causes of diseases such as demons, stars and witchcraft.
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Heat appliedLet flask sit
Remove the neck and let sit
Tilt flask sideways and let it sit
No bacteria present
Bacteria present
Bacteria presentHeat Applied
Heat Applied
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The role of modern scientists in the cure of diseases
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Activity 41. Tabulate the causes, effects, symptoms and treatments of the diseases caused by micro-
organisms
Disease Causes Effects Symptoms Treatment
Tuberculosis
AIDS
Malaria
Waterborne diseases
2. Who was Louis Pasteur?
3. Explain three methods of prevention of diseases.
Useful micro-organisms Some micro-organisms play an essential role in ecosystems, such as decomposing dead plant and animal matter, thereby recycling nutrients in the soil. Some micro-organisms are used by people for making certain foods (such as yoghurt) and medicines (such as penicillin).
DecomposersWhen an organism dies, micro-organisms such as bacteria and fungi start to digest the dead or decaying body. This is called decomposition.
The process of decomposition releases nutrients that were stored in the organism’s body back into the soil. This keeps the soil fertile and new plants use these nutrients to grow big and strong.
GRADE 8 TERM 1 NATURAL SCIENCES TYPES OF MICRO-ORGANISMS
Using micro-organisms to make medicinesSir Alexander Fleming Fleming discovered the anti-biotic called penicillin when he noticed that a bacterial culture had been contaminated with a fungus. He saw that the bacteria surrounding the fungus had been destroyed. He realised
that the fungus was producing a substance that killed the bacteria. Many diseases could now be treated with penicillin.
Using micro-organisms to make food• Micro-organisms are used to make food.• Yeast is used to make bread rise and wine brew.• Certain bacteria are used to make yoghurt and cheese.
Yoghurt is made by adding a bacterial culture to milk and allowing it to ferment.
• Some cheese needs mould to grow to help ripen and mature it such as Camembert and Brie.
Activity 51. What are decomposers?
2. Why were Sir Alexander Fleming’s findings so beneficial?
