There are tiny organisms everywhere in the world which cannot be seen with the naked eye. They are located in water, on land, and in the air. They can be found in people's homes, workplaces, and even in places that seem to be spotlessly clean. These tiny organisms are called microorganisms or microbes. There are five different types: bacteria, viruses, fungi, protozoa, and algae.

They are the smallest and simplest kind of living things, numbering into the billions upon trillions, and can only be seen using a microscope. They come in all kinds of varieties, shapes and sizes. They can be found alone or in groups called colonies. There are more microbes on the planet than any other kind of living organism. There are some called heterotrophic, which depend on other living organisms to survive. Others make their own food, just like plants, and are called autotrophic. Microorganisms can reproduce sexually, parents are involved, or asexually, no parent cells are joined.

The microorganisms live in cold, hot, wet, and dry climates living between rocks, in caves, deep below the ocean, at the North Pole, or in food which can then be dangerous to consume. However, there are microorganisms which are beneficial to other living organisms as well.

Many of them have symbiotic relationships, meaning they benefit themselves and the larger organisms. Some of the relationships are beneficial, but others can be damaging to a larger organism. Some of the microorganisms can cause a disease and are known as pathogens. This is how many people become ill.

An example of a beneficial microorganism is a bacterium in milk which helps convert milk to curd. Microorganisms are also helpful in other food-making such as brewing, winemaking, and baking. Microorganisms are vital to the food, nitrogen, and carbon cycles, and they have a key role in virtually all ecosystems. Microorganisms, such as bacteria, help with breaking down the dead and decaying organisms' remains through decomposition increasing the soils fertility. They are used for making medicines such as the antibiotics a person takes when they have a flu or fever. Some bacteria and fungi are used to make the medicines. In addition, some vaccines are dead or weakened versions of microbes used to help the body produce natural antibodies to prevent diseases like polio, cholera, typhoid, small pox, hepatitis and others.

Though microbes are extremely valuable to people and other organisms, they can also become harmful and deadly. They can cause diseases in plants and animals, as well as grow in various food substances. The food can become poisonous causing a person serious illness or even death. There are microorganisms that can spoil items in the home like clothing, leather, wood and many others.

Microorganisms can cause many of the infectious diseases as well, such as the pathogenic bacteria causing plague, tuberculosis and anthrax. Protozoa can cause malaria; fungi can cause ringworm. All of the disease-causing microbes can enter a person's body through the air, water, food, or contact with others, or by insects.

In summary, there are trillions and trillions of microorganisms found in every corner of the globe, in all types of climates. They are extremely tiny and can only be seen under a microscope. The microorganisms include bacteria, viruses, fungi, protozoa, and algae. Some microbes are dangerous to other living organisms, but many are helpful. Disease causing microbes can enter a person's body in several different ways such as through the air, water, or food, and can also spread from one person to another through contact.

A: Bacteria
B: Viruses, protozoa
C: Fungi, algae
D: Plant cells

A: Herds
B: Antibodies
C: Colonies
D: Hives

A: Depends on other organisms to survive
B: Can survive by making its own food
C: Survives only on plants
D: Uses other organisms to survive and can make its own food

A: Depends on other organisms to survive
B: Can survive by making its own food
C: Survives only on plants
D: Uses other organisms to survive and can make its own food

A: Microbes are extremely valuable to people and other organisms
B: Bacteria help with breaking down dead and decaying organisms' remains
C: Microorganisms can be harmful and deadly
D: Fungi can cause malaria; Protozoa can cause ringworm

A: Bacteria and fungi
B: Fungi and protozoa
C: Protozoa and bacteria
D: Algae and viruses

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