Grade 10 general science β Microorganisms Quiz
1. Which of the following is NOT a type of microorganism?
Insects are multicellular animals visible to the naked eye and are not classified as microorganisms. Bacteria, viruses and fungi can be microscopic.
2. What is the main way most bacteria reproduce?
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.
3. Which statement correctly distinguishes viruses from 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.
4. Which microorganism is the cause of malaria?
Malaria is caused by protozoan parasites of the genus Plasmodium, which are transmitted to humans by Anopheles mosquitoes.
5. Which of the following diseases is caused by a bacterium?
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.
6. Which practice helps make drinking milk safer by killing many harmful microorganisms?
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.
7. Which microorganisms fix atmospheric nitrogen in root nodules of beans and other legumes?
Rhizobium bacteria form symbiotic relationships with legume roots and convert atmospheric nitrogen into forms the plant can use, improving soil fertility.
8. Why are antibiotics not effective against viral infections?
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.
9. Which Kenyan food or product commonly involves beneficial microorganisms during preparation?
Uji is often prepared by fermentation using naturally occurring bacteria or yeasts, which improve flavor and sometimes digestibility. Fresh roasted maize or boiled tea donβt rely on microbial fermentation.
10. Which microorganism group includes yeasts used in bread making?
Yeasts are single-celled fungi (e.g., Saccharomyces cerevisiae) that ferment sugars to produce carbon dioxide and alcohol, causing bread to rise.
11. What is a safe household method to reduce microbes in drinking water?
Boiling water kills most disease-causing microorganisms. Leaving water uncovered or adding sugar does not make it safe.
12. Which microorganism causes the disease tuberculosis (TB)?
Tuberculosis is caused by the bacterium Mycobacterium tuberculosis and is transmitted mainly via droplets when an infected person coughs or sneezes.
13. In a classroom microscope practical, which stain is commonly used to see bacteria more clearly by increasing contrast?
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.
14. Which role do decomposer microorganisms play in the environment?
Decomposer bacteria and fungi break down dead plants and animals, releasing nutrients that plants can reuse, maintaining ecosystem nutrient cycles.
15. What is the main purpose of the Gram stain in microbiology?
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.
16. Which microorganism is responsible for athlete's foot and ringworm?
Athlete's foot and ringworm are caused by fungi called dermatophytes that infect skin, hair and nails.
17. Algae in freshwater lakes are important because they:
Photosynthetic algae produce oxygen and serve as primary producers that support aquatic food chains.
18. Why is handwashing with soap effective at reducing disease spread?
Soap emulsifies oils that trap microbes and can disrupt membranes of some microbes, allowing them to be rinsed away, reducing disease transmission.
19. Which of the following is a viral disease that has vaccines available in Kenya?
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.
20. What is the role of fermented foods in relation to microorganisms?
During fermentation, yeasts and bacteria produce acids, alcohols and enzymes that preserve food, change flavour and sometimes increase nutritional value.
21. Which method is used in laboratories to grow and study bacteria safely?
Lab cultures on sterile agar allow scientists to grow, isolate and study bacteria safely under controlled conditions with proper aseptic technique.
22. A student observes small, moving single-celled organisms in pond water under a microscope. These are most likely:
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.
23. Which practice contributes to antibiotic resistance in communities?
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.
24. During a practical, how should a student dispose of used microbial culture plates to be safe?
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.
25. Which statement best describes the size ranking from smallest to largest among these microorganisms?
Viruses are the smallest, followed by bacteria, then protozoa (single-celled eukaryotes), and fungi which are often larger (including multicellular forms).