Microorganisms Overview Quiz

Microorganisms

• Microorganisms are tiny, single-celled living organisms that can be seen only with a microscope
• They include bacteria, viruses, protozoa, fungi and algae.
• They are found in a wide variety of environments, including inside other organisms.

Bacteria

• Bacteria were among the first living things to appear on Earth.
• They have different shapes: spherical (cocci), spiral (spirilla) and rod-shaped (bacilli).
• Examples include Streptococcus and Lactobacillus.

Viruses

• Viruses infect all life forms.
• They come in various shapes and sizes.
• Examples include the papillomavirus (can cause cancer) and the varicella zoster virus (chickenpox virus).

Protozoa

• Protozoa are single-celled organisms that thrive in soil and aquatic environments.
• Examples include Amoeba and Euglena.

Fungi

• Fungi are plant-like organisms that do not contain chlorophyll.
• Examples include mushrooms and yeast.

Algae

• Algae include single-celled and multicellular organisms.
• They are simple plant-like organisms found in water bodies, rocks and snow.
• Examples include Spirogyra and Chlorella.

Milestones in Microorganism Discovery

• Antonie van Leeuwenhoek (1632-1723) first observed microorganisms with the help of his microscope.
• Louis Pasteur (1822-1895) discovered that microorganisms in the air spoil food and are the cause of fermentation and decay, as well as diseases.
• Robert Koch (1843-1910) developed techniques for handling bacteria to study anthrax and prove it was caused by specific microorganisms.
• Joseph Lister (1827-1912) was the first to eliminate bacteria from operating theatres by using carbolic acid, a disinfectant.

Where are Microorganisms Found?

• Microorganisms are found in almost every kind of environment, including inside other organisms.
• A single gram of soil can contain a vast number of bacteria.
• The air you breathe, your skin, fingernails, and intestines all harbor microorganisms.

Conditions for Microorganism Growth

• Different microorganisms have different needs and grow in a wide range of conditions.
• Oxygen: Some require oxygen (aerobic) while others do not (anaerobic).
• Water: Moisture is essential for most microorganisms to thrive.
• Temperature: Some microorganisms can tolerate extreme temperatures, but most thrive between 25 °C and 38 °C.
• Darkness: Many microorganisms thrive in dark places, but photosynthetic microorganisms need light.
• Food Supply: Microorganisms live and feed on a wide range of materials, including dead organisms (saprophytes), tissues of host organisms (parasites), and through photosynthesis.

Useful Microorganisms

• Microorganisms are important for increasing soil fertility.
• Bacteria and fungi decompose dead organisms and organic matter, releasing nutrients back into the soil.
• Nitrogen-fixing bacteria, like Rhizobium, convert nitrogen to ammonia in legume root nodules, increasing soil fertility.

Nitrogen Cycle - A circular pathway of nitrogen in nature

• Nitrogen is the most abundant element in Earth's atmosphere, but most organisms cannot use it directly.
• Nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia.
• Nitrifying bacteria convert ammonia into nitrites and then nitrates.
• Plants take in nitrates, and animals obtain nitrogen through consuming plants or other animals.
• Decomposers break down dead organisms and release ammonia back into the soil, restarting the cycle.
• Denitrifying bacteria convert nitrates back into atmospheric nitrogen.

Test your knowledge on various microorganisms including bacteria, viruses, protozoa, fungi, and algae. This quiz covers their characteristics, examples, and environments. Perfect for biology students learning about these fundamental organisms.