Microscopic Organisms Quiz

Microscopic Organisms: A Summary

• Microorganisms are organisms of microscopic size, which may exist in their single-celled form or as a colony of cells.

• The scientific study of microorganisms began with their observation under the microscope in the 1670s by Anton van Leeuwenhoek.

• Microorganisms can be extremely diverse and include most unicellular organisms from all three domains of life.

• Microorganisms can have very different habitats, and live everywhere from the poles to the equator, deserts, geysers, rocks, and the deep sea.

• Microbes are important in human culture and health in many ways, serving to ferment foods and treat sewage, and to produce fuel, enzymes, and other bioactive compounds.

• Microorganisms make up the microbiota found in and on all multicellular organisms.

• Microorganisms were discussed for many centuries before their discovery in the seventeenth century.

• Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic.

• Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3.5 billion years ago.

• Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species.

• Archaea differ from bacteria in both their genetics and biochemistry. For example, while bacterial cell membranes are made from phosphoglycerides with ester bonds, archaean membranes are made of ether lipids.

• Most living things that are visible to the naked eye in their adult form are eukaryotes, including humans. However, many eukaryotes are also microorganisms.Microorganisms: Their Diversity, Ecology, and Applications

• Unicellular eukaryotes reproduce asexually by mitosis under favorable conditions and sexually by meiosis and syngamy under stressful conditions.

• Protists are a highly diverse group of organisms that are not easy to classify, and their diversity is high in different habitats, suggesting that many eukaryotic microbial communities may be undiscovered.

• Fungi have several unicellular species such as baker's yeast and fission yeast, but some fungi can grow as single cells in some environments and filamentous hyphae in others.

• Microorganisms are found in almost every habitat present in nature, including hostile environments such as the North and South poles, deserts, geysers, and rocks.

• Extremophiles are microorganisms that have adapted so that they can survive and thrive in extreme environments that are normally fatal to most life-forms.

• The nitrogen cycle in soils depends on the fixation of atmospheric nitrogen, which is achieved by a number of diazotrophs.

• The roots of plants create a narrow region known as the rhizosphere that supports many microorganisms known as the root microbiome.

• Microorganisms are useful in producing foods, treating wastewater, creating biofuels and a wide range of chemicals and enzymes, and they are invaluable in research as model organisms.

• Microorganisms are essential tools in biotechnology, biochemistry, genetics, and molecular biology, and scientists are also considering using microorganisms for living fuel cells and as a solution for pollution.

• Microorganisms are the causative agents in many infectious diseases, such as tuberculosis, malaria, and candidiasis, and hygiene is a set of practices to avoid infection or food spoilage by eliminating microorganisms from the surroundings.

• Microorganisms play critical roles in Earth's biogeochemical cycles as they are responsible for decomposition and nitrogen fixation.

• Microorganisms have been weaponized and sometimes used in warfare and bioterrorism.