Microorganisms
Category : 8th Class
A microorganism or microbe are the living organisms, which are too small to be visible to the naked eyes. The study of microorganisms is called microbiology. The microorganism are bacteria, fungi, etc. However, viruses and prions are not microorganisms, they are classified as nonliving. They are found everywhere on the earth, including water, air and land. They are also called extermophiles. They act as a decomposer, and help in nutrient recycling in ecosystem. Pathogenic or harmful microbes can invade other organisms and cause disease.
Useful Microbes
There are some microorganisms, which are useful to us; where as some of them are harmful. The useful microorganisms feed on the things that were once living. The decayed materials get mixed with the soil and provide essential nutrients for plants to grow. Such organisms are called decomposers. Without decomposers, the soil would not have got the nutrients, and would have run out of it. They are the natural recyclers of living things on earth.
Harmful Microbes
Some microbes can cause illness or disease, such as, chickenpox, mumps and measles. These are infectious diseases. Some microbes can cause food decay. For example, moldy bread or fruit, sour milk and rotten meat etc. If we take these rotten food, it can cause stomach upset and many other health problems.
Haden prepared soup for himself. Due to some urgent work, he could not take the soup and went to his office. When he returned next day from his office, he found that the soup was spoiled and emitting bad smell. Which one of the following microorganism had spoiled the soup?
(a) Bacteria
(b) Virus
(c) Fungus
(d) Plasmodium
(e) None of these
Answer: (a)
Explanation
The microorganism which spoils the liquid food is bacteria.
The microorganisms, which are found everywhere on the earth i.e. on the land, water, and air are called:
(a) Extermophiles
(b) Prions
(c) Pathogens
(d) Moulds
(e) None of these
Answer: (a)
Explanation
Extermophiles are the microorganisms, which are found everywhere on the earth.
Difference between Plant Cell and Animal Cell
Plant Celt | Animal Cell |
1. A plant cell has cell wall. | 1. Animal cell has no cell wall. |
2. It has plastid which contains chlorophyll. | 2. It has no plastids. |
3. It has large vacuole in it. | 3. The vacuole in the animal cell are usually small. |
4. Centrosomes is absent. | 4. Centrosomes is present. |
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