Grade 10 general science – Microorganisms Quiz

Insects are multicellular animals visible to the naked eye and are not classified as microorganisms. Bacteria, viruses and fungi can be microscopic.

Most bacteria reproduce asexually by binary fission, where one cell divides into two genetically similar cells. Some microbes like fungi use spores and some yeasts bud, but binary fission is typical for bacteria.

Bacteria are generally larger and can grow and reproduce independently, whereas viruses are much smaller and require a host cell's machinery to replicate.

Malaria is caused by protozoan parasites of the genus Plasmodium, which are transmitted to humans by Anopheles mosquitoes.

Cholera is caused by the bacterium Vibrio cholerae. Measles and the common cold are viral, and HIV/AIDS is caused by the human immunodeficiency virus.

Pasteurization involves heating milk to a specific temperature briefly to kill many harmful microbes while preserving nutritional quality; simply letting milk sit or filtering through cloth does not reliably eliminate pathogens.

Rhizobium bacteria form symbiotic relationships with legume roots and convert atmospheric nitrogen into forms the plant can use, improving soil fertility.

Antibiotics interfere with bacterial cell walls, protein synthesis or other bacterial-specific processes; viruses lack these structures and use host cells to replicate, so antibiotics do not work on them.

Uji is often prepared by fermentation using naturally occurring bacteria or yeasts, which improve flavor and sometimes digestibility. Fresh roasted maize or boiled tea don’t rely on microbial fermentation.

Yeasts are single-celled fungi (e.g., Saccharomyces cerevisiae) that ferment sugars to produce carbon dioxide and alcohol, causing bread to rise.

Boiling water kills most disease-causing microorganisms. Leaving water uncovered or adding sugar does not make it safe.

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis and is transmitted mainly via droplets when an infected person coughs or sneezes.

Simple stains like crystal violet color bacterial cells so they are easier to see under a light microscope. Without staining bacteria are often hard to see because they are nearly transparent.

Decomposer bacteria and fungi break down dead plants and animals, releasing nutrients that plants can reuse, maintaining ecosystem nutrient cycles.

The Gram stain differentiates bacteria based on cell wall properties: Gram-positive retain crystal violet and appear purple, while Gram-negative do not and appear pink after counterstaining.

Athlete's foot and ringworm are caused by fungi called dermatophytes that infect skin, hair and nails.

Photosynthetic algae produce oxygen and serve as primary producers that support aquatic food chains.

Soap emulsifies oils that trap microbes and can disrupt membranes of some microbes, allowing them to be rinsed away, reducing disease transmission.

Measles is caused by a virus and effective vaccines are part of routine immunisation programs. Cholera is bacterial, ringworm is fungal, and giardiasis is protozoan.

During fermentation, yeasts and bacteria produce acids, alcohols and enzymes that preserve food, change flavour and sometimes increase nutritional value.

Lab cultures on sterile agar allow scientists to grow, isolate and study bacteria safely under controlled conditions with proper aseptic technique.

Protozoa are single-celled, often motile organisms commonly seen moving in pond water under a light microscope; viruses are too small to see with a basic light microscope.

Misuse of antibiotics (overuse, underuse or incomplete courses) allows bacteria to survive and develop resistance; good hygiene and vaccination help prevent infections and reduce antibiotic use.

Used culture plates may contain live microbes and must be decontaminated (e.g., autoclaved) and discarded as biohazardous waste following safety protocols to prevent contamination and spread.

Viruses are the smallest, followed by bacteria, then protozoa (single-celled eukaryotes), and fungi which are often larger (including multicellular forms).

Microorganisms are generally microscopic (bacteria, viruses, protozoa, many fungi) and require a microscope to be seen; some fungi produce larger structures but most microbes are too small for the naked eye.

Influenza is caused by an influenza virus; E. coli is a bacterium, yeast is a fungus, and amoeba are protozoa.

Malaria is caused by Plasmodium species (a protozoan); the Anopheles mosquito transmits the parasite but is not the microorganism that causes the disease.

Rhizobium bacteria form nodules on legume roots and convert atmospheric nitrogen into forms plants can use, improving soil fertility.

Pasteurization uses controlled heating to kill many pathogens in milk without severely affecting its nutritional value; filtration or freezing do not reliably kill pathogens.

Antibiotics target bacteria and have no effect on viruses such as influenza; viral infections require antiviral treatment or supportive care.

Bacteria are cellular and have a cell membrane (and often a cell wall); viruses are not cells and lack a cell membrane, having only a protein coat and genetic material.

Baker's yeast ferments sugars producing carbon dioxide that makes dough rise; E. coli and Rhizobium are bacteria, Paramecium is a protozoan.

Binary fission is how many bacteria reproduce asexually: the cell copies its DNA and splits into two genetically similar daughter cells.

Autoclaving uses high-pressure steam to reliably sterilize instruments by killing bacteria, spores and many viruses; sun drying, freezing or cloth filtration do not sterilize.

Decomposers (bacteria and fungi) break down dead plants and animals, returning nutrients to the soil for use by living organisms.

Lactobacillus species are probiotic bacteria that help digestion and are used in fermented foods like yoghurt; Salmonella is a pathogen, influenza a virus, Plasmodium a protozoan.

Vibrio cholerae is the bacterium that causes cholera, a severe diarrhoeal disease often spread via contaminated water.

Boiling water kills most disease-causing microorganisms; adding sugar or simple cloth filtration do not reliably make water safe.

Ringworm is caused by dermatophyte fungi; it is not caused by bacteria, viruses or protozoa.

Goggles and gloves reduce the risk of infection or contamination from accidental spills, splashes or touching contaminated surfaces during experiments.

Viruses are obligate parasites that must enter host cells to replicate; they cannot reproduce independently. They are generally smaller than bacteria and usually carry either DNA or RNA, not both.

Lower temperatures slow the metabolism and reproduction of many bacteria, helping to keep food safe longer; warmth and moisture promote bacterial growth.

Generally viruses are smallest, bacteria are larger, protozoa (single-celled eukaryotes) are larger still, and many fungi have the largest cells or multicellular structures.

Gram staining differentiates bacteria by cell wall structure into Gram-positive and Gram-negative, which helps guide treatment and identification.

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis; other options cause different diseases (pneumonia, flu, malaria).

Vaccines expose the immune system to safe parts of a pathogen or weakened forms so the body builds memory cells and can fight the disease if exposed later.

Culturing on nutrient agar provides bacteria with nutrients and a surface to grow, allowing observation and study under controlled conditions; the other methods are not appropriate for growing and observing bacteria.

Streptococcus mutans is a bacterium that metabolizes sugars to produce acids that demineralize tooth enamel, leading to cavities.

Fungi do not photosynthesize; they obtain nutrients by absorbing organic matter. They do have chitin cell walls, reproduce by spores, and many are decomposers.