18 Questions
Which of the following microorganisms is characterized by lacking peptidoglycan in their cell walls?
Archaea
What is the distinguishing factor of viruses compared to other microbial groups?
Acellular nature
Which domain does not strictly contain microorganisms?
Animalia
Among the listed microorganisms, which one is photosynthetic?
Algae
What distinguishes protozoa from other microbes in terms of movement?
Pseudopods
Which microbial group is characterized by being unicellular eukaryotic microbes?
Protozoa
What term describes a complex aggregation of microbes that attach to each other and/or a solid surface?
Biofilm
Which microorganism is commonly used in insect pest control due to its properties?
Bacillus thuringiensis
What is the term used to describe a disease in which pathogens invade a susceptible host?
Infectious disease
What is the primary function of some normal microbiota in the human body?
To benefit the host
Which term is used to describe diseases that have recently emerged and are on the rise?
Emerging infectious diseases
Where do microorganisms in biofilms commonly attach in nature?
To each other and/or solid surfaces
Who devised a system of classification based on the cellular organization of organisms in 1978?
Carl Woese
Which of the following is a characteristic of Archaea?
Lack of peptidoglycan in cell walls
Who is credited with the discovery of 'cells' as the smallest structural units of life?
Robert Hooke
What term did Anton van Leeuwenhoek use to describe the microorganisms he saw through his microscopes?
Animalcules
Which group do flatworms and roundworms collectively belong to?
Helminths
What is the major difference between Bacteria and Archaea in terms of cell walls?
Presence of peptidoglycan in Bacteria but not in Archaea
Study Notes
What is Microbiology?
- Study of the biology of microscopic organisms, such as viruses, bacteria, algae, fungi, protozoa, etc.
- Involved in the origin and evolution of life
Microbes or Microorganisms
- Living things too small to be seen with the unaided eye
- Important in maintaining Earth's ecological balance
- Some microorganisms live in humans and other animals, necessary for good health
- Some microorganisms are used to produce foods and chemicals
- Some microorganisms cause disease
Types of Microorganisms
- Bacteria: relatively simple, single-celled (unicellular) organisms
- Archaea: prokaryotic cells, but if they have cell walls, the walls lack peptidoglycan
- Fungi: eukaryote, organisms with a distinct nucleus containing DNA
- Protozoa: unicellular eukaryotic microbes, move by pseudopods, flagella, or cilia
- Algae: photosynthetic eukaryotes with a wide variety of shapes and reproductive forms
- Viruses: very small, acellular, seen only with an electron microscope
- Multicellular animal parasites: not strictly microorganisms, but of medical importance
Microbes and Human Disease
- Normal microbiota (flora) do not harm humans, and some even benefit us
- Normal microbiota protect us against disease by preventing harmful microbes overgrowth
- Several types of bacteria found on the human tongue surface as part of the normal microbiota
Biofilms
- Microorganisms exist as single cells or attach to each other and/or solid surfaces, forming a complex aggregation of microbes
- Biofilm formation on a catheter
Infectious Diseases
- Disease caused by pathogen invasion of a susceptible host
- Emerging infectious diseases (EIDs) are increasing, with recent outbreaks and new diseases
Classification of Microorganisms
- Carl Woese's system of classification (1978) groups organisms into three domains:
- Bacteria: cell walls contain peptidoglycan
- Archaea: cell walls lack peptidoglycan
- Eukarya: includes protists, fungi, plants, and animals
History of Microbiology
- Robert Hooke discovered cells in 1665, observing a thin slice of cork through a microscope
- Anton van Leeuwenhoek observed live microorganisms through his microscopes, writing about "animalcules" between 1673 and 1723
Test your knowledge on the classification of parasitic worms like flatworms and roundworms, as well as microorganisms such as bacteria, archaea, and fungi. Explore the history of microbiology and Carl Woese's three-domain system of classification.
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