What Are Microorganisms?
Our environment is full of living organisms, some of which cannot be seen with the naked eye.
These minute and tiny organisms are called microorganisms.
“Micro” means very small and “organism” means living.
These organisms are too small for us to see but are present everywhere:
-in the air,
-in water,
-in soil,
-in our body,
-and on the surface of every object.
They are even present in the food we eat.
They affect our lives in many ways.
Universal Characteristics of Microorganisms
All microorganisms are living things or organisms.
Microorganisms may be unicellular or single-celled.
Microorganisms require :
– food
– air
– water
– ways to dispose of waste
– environment in which they can live.
Some microorganisms are producers – (living things that make their own food from simple substances) usually using sunlight (like plants do).
Some microorganisms eat other organisms to get their food.
Some microorganisms are useful, some are harmful. —-> They make us sick.
All microorganisms that cause diseases are called germs.
Historical Perspective
Microorganisms have been on Earth for about 3.5 billion years.
They play an extremely important part in sustaining life on our planet.
Classification of Microorganisms
Viruses
Basic Properties of Viruses
A virus is a very small sized germ which can make living things ill. They make cells work abnormally. Because viruses are so small, they can only be seen by very powerful microscopes.
Viral Distribution and Spread
Viruses can be found almost everywhere. When a virus enters the body of a human being, it can spread very fast.
Viral Diseases and Health Impact
Viruses are very dangerous to our health. Viruses cause diseases such as: Cold, Influenza, Measles, Polio, Hepatitis, and Smallpox. They can enter the body through the nose, the mouth, or cuts in the skin.
Common Viral Examples
- Common cold virus
- Influenza virus
- Measles virus
- Chickenpox virus
- COVID-19 coronavirus
Dengue Virus: A Case Study
Dengue virus (DENV) is transmitted through mosquitos. Some dengue virus infections are mild, others can cause an acute flu-like illness. Severe dengue is one of the major causes of serious illness and death in Pakistan.
Dengue Symptoms
Symptoms of dengue include:
- Severe headache
- Pain behind the eyes
- Muscle and joint pains
- Nausea
- Vomiting
- Rash
Dengue Prevention Strategies
- Keep the surroundings clean
- Keep doors, windows, etc. covered with net
- Sleep under mosquito nets
- Apply mosquito repellent
Bacteria
Bacterial Characteristics
Bacteria are everywhere but you can’t see them.
Bacteria are microscopic life forms that live on and in other living things.
They belong to the kingdom Monera.
They are known as microscopic because they are so small they can only be seen through a microscope.
Bacteria are the simplest forms of living things. They only have one cell. In comparison, a human is made up of trillions of cells.
Bacterial Role in Nature
The role of bacteria is to act as decomposers. They breakdown the chemical elements inside other organisms.
Bacterial Diseases
Some germs are bacteria.
Bacteria cause diseases such as:
– Cholera,
– Typhoid,
– TB (Tuberculosis),
– Food poisoning,
– and Throat infection.
Bacteria in the mouth causes tooth decay.
Fungi
Evolution of Fungal Classification
For a long time, scientists classified fungi as plants. However, the more scientists learned about fungi, the more they realized fungi belonged in a kingdom of their own.
Fungi vs. Plants Comparison
| Plants | Fungi |
|---|---|
| Have stems, leaves, and roots | Do not have stems, leaves, and roots |
| Some plants have flowers | Do not have flowers |
| Are able to produce their own food | Are not able to produce their own food |
Shared Characteristics
One thing that fungi have in common with some plants is that they have spores for reproduction.
Fungal Feeding Mechanisms
Because they are unable to make their own food, fungi have to find their food. They do this by attaching themselves to other living things.
Fungi on Animals
Some fungi attach themselves to animals, including humans. If you do not wash properly and find that your body becomes itchy, it may be because a fungus is growing on you.
Fungi on Plants
Some fungi attach themselves to plants. Mushrooms and toadstools are examples of fungi that do this. If you see mushrooms on a tree or around the base of a tree, you will know that the mushrooms are getting their nourishment from the cells of that tree.
Protists
Major Categories of Protists
There are two main types of protists: protozoa and algae.
1. Protozoa
Protozoan Characteristics
Like bacteria, protozoa are microscopic single-cell organisms. However, they do not live on other organisms; they are free living. That means they can easily move from one organism to another. Some protozoa are eaten by fish. Others cause diseases in animals. Protozoa have an animal-like cells.
Amoeba: A Protozoan Example
One type of protozoa is the amoeba. Amoebae live in water, among rotting food, and in humans. They are advanced enough to have arm-like structures that help them grasp food particles and move.
2. Algae
Algal Characteristics
Algae have a plant-like cell. While most algae have just one cell, some have multiple cells. Algae live in water and are able to make their own food from sunlight. Some algae are microscopic but some are much larger. Seaweed is an example of algae.
Beneficial Roles of Microorganisms
Natural Ecosystem Functions
Decomposition and Nutrient Cycling
Some bacteria and fungi cannot make their own food. They feed on dead plants and animals. They produce a liquid which dissolves the dead plant or animal they are feeding on. Then they absorb the liquid back into themselves. This process breaks down large, complex chemicals in dead organisms into small, simple chemicals. Decomposers are natural recyclers. They return the basic chemicals to the environment for other living organisms to use.
Fungi living on plants help cause plants to rot and decay when they die. Dead plants and animals decompose, releasing their nourishment into the soil. This decomposition enables new life to grow.
Waste Management
Microorganisms break down wastes at sewerage plants. This breakdown makes waste disposal easier and safer.
Food Production and Processing
Dairy and Fermented Products
Bacteria are used to make milk products including yoghurt, cheese, sour cream, and buttermilk. Bacteria are used to make vinegar.
Yeast Applications
Yeast (a fungus) is used to bake bread. Yeast is also used to make soy sauce, salami, and black tea, and to prepare olives.
Human Health Support
Digestive System Benefits
The human body contains tens of millions of microorganisms. Some microorganisms provide humans with nutrients. Others break down food to make it easier to digest. They break down large food particles into tiny usable ones.
Harmful Effects of Microorganisms
Disease-Causing Impact
Some microorganisms have caused more harm to humans than all wars combined. Disease-causing microorganisms include bacteria and protozoa.
Specific Disease Examples
Protozoal Diseases
Malaria is caused by a protozoan.
Bacterial Diseases
Bacterial diseases include: tuberculosis, diphtheria, typhoid fever, cholera, dysentery, and pneumonia.
Viral Diseases
Covid-19 pandemic resulted from a virus (similar to the common cold).
Other Forms of Damage
Lower-level harm includes damage to clothes, shoes, carpets, and other textiles. Food contamination is another form of harm.
Understanding and Preventing Infections
The Infection Process
How Infections Develop
Infections are caused by microorganisms getting into the body. Once harmful microorganisms get into your body, they reproduce rapidly. They feed on the body cells and produce poisonous waste substances called toxins.
Infection Progression
As their numbers increase, more cells are damaged and more toxins are produced. You begin to feel ill – this is called an infection. Sometimes infections affect only a particular part of the body (like the eyes, lungs, etc.). Sometimes they might affect the whole body, causing fever.
Body’s Natural Defense
Our body tries to fight these germs with the help of white blood cells. Sometimes we need to take medicines like antibiotics to kill the germs.
Food Safety and Contamination Prevention
Understanding Food Spoilage
When leftover food is left outside at room temperature, it will go bad. Bacteria and fungi land on the food from air. These microorganisms produce chemicals in the food. The chemicals make humans ill, causing food poisoning.
Food Safety Guidelines
Cooking and Temperature Control
- Cook food until it is really hot
- If food is too hot, people can wait until it reaches the right temperature to eat
- Check that food is hot all the way through by poking a skewer through it or cutting a piece with a knife
- Sometimes when you heat a thick piece of food, the middle does not cook through enough
- Stir food when heating so that the heat is evenly distributed
Hygiene Practices
- Wash your hands before handling food
- Wash your hands during the food handling process
- Do not chop food on a chopping board that has been used but not washed
Storage and Handling
- Do not let heated food sit for too long before being eaten
- This prevents giving bacteria a chance to contaminate the food again
- Do not reheat food more than once
- Make sure that frozen foods are properly thawed before heating them
Medical Interventions and Disease Control
Treatment Methods
Antibiotics
Microorganisms that destroy other microorganisms are used to create antibiotics. Antibiotics are medicines that help fight diseases. Antibiotics work by destroying, slowing down, or preventing the growth of bacteria to cure bacterial infections.
Historical Development
The first antibiotic, Penicillin, was discovered in 1928 by Alexander Fleming from the fungi penicillin mould. Penicillin has saved millions of people from dying from diseases.
Antibiotic Limitations
Important limitation: Antibiotics are useless against infections caused by viruses, such as cold, flu, etc.
Vaccines
While antibiotics fight diseases that have already started to infect the body, vaccines help to stop diseases becoming infectious. Vaccines are made from microorganisms that are the cause of infectious diseases. They work by giving the body a small amount of that disease so that the body can produce antibodies that can fight the virus in the future.
General Prevention Strategies
Health Practices
Good hygiene helps defend against illness. Getting vaccinations and regular checkups are important. When unwell, people should wear masks, take proper medications, and practice social isolation to prevent spread of infections.
Environmental Controls
High temperatures can kill microorganisms. Food that might contain dangerous microorganisms should be well cooked before eating.
QUESTIONS & ANSWERS
1. What are the three main differences between plants and fungi?
Plants have stems, leaves, and roots, while fungi don’t. Plants can also produce their own food, but fungi cannot and must find food by attaching to other living things. Finally, some plants have flowers, but fungi never do.
2. What are the two main types of protists?
The two main types of protists are
protozoa and algae.
3. What is the number of cells that bacteria have?
Bacteria are microscopic life forms that have only one cell. In comparison, a human body has trillions of cells.
4. What is the role of bacteria?
The primary role of bacteria in the ecosystem is to act as
decomposers. They break down the chemical elements within other organisms. Some bacteria are also used in food production to make things like yogurt, cheese, and vinegar.
5. What are two things that fungi attach themselves to?
Fungi attach themselves to other living things to get food. They can attach to
animals, including humans, and to plants.
Based on the provided document, here are the answers to the questions.
Questions from the first image
- Why must food be made free of bacteria?Food must be made free of bacteria because some bacteria can make humans sick and cause food poisoning11111.
- How can food be made safe?You can make food safe by cooking it until it is very hot2222. Other ways to prevent food poisoning include:
- Washing your hands before and during food preparation3.
- Not using a dirty chopping board4.
- Not letting heated food sit out for too long5.
- Stirring food to make sure the heat is spread evenly6.
- Not reheating food more than once7.
- Thawing frozen food properly before you cook it8.
Questions from the second image
- What are these?
- a. a tiny amount of bacteria or virus that is given to a human to protect them against a stronger strain of that bacteria or virus – This is a vaccine.
- b. microscopic life forms that live on and in other living things – This is bacteria.
- c. a medicine that helps fight diseases – This is an antibiotic.
- d. these attach themselves to other living things for survival – This is fungi.
- Write about any two ways in which microorganisms help us.Microorganisms help us in many ways, including:
- Decomposition: Some bacteria and fungi break down dead plants and animals. This process returns important nutrients to the soil so new life can grow.
- Food production: Bacteria are used to make foods like yogurt, cheese, and vinegar. Yeast, which is a type of fungus, is used to bake bread and make soy sauce.
- What are mushrooms? How do they grow?
Mushrooms are a type of fungi.
They grow by attaching to other living things, like a tree, to get their food because they cannot make it themselves. - How do antibiotics work?
Antibiotics are medicines that work by either killing bacteria or stopping them from growing. They are used to treat infections caused by bacteria. - What are protists? How do they survive?
Protists are simple organisms that are not plants, animals, or fungi.
The two main types are protozoa and algae.
Protozoa are single-celled and can move freely , while algae live in water and can make their own food using sunlight. - What is an amoeba? Explain with the help of a diagram.
An amoeba is a type of protozoa.
It is a single-celled organism that lives in water, rotting food, and in humans.
It has arm-like parts that help it move and grab food. - In your opinion are microorganisms helpful to human life or harmful?
Microorganisms can be both helpful and harmful to human life.
They can be helpful by breaking down dead matter and helping with food production, but they can also be harmful because they can cause diseases and make food go bad.