13.1.1 World of Microorganisms (Q&A)

Short Answer Questions

1. What are microorganisms?
   Answer
   Microorganisms, also known as microbes, are tiny organisms that are only visible under a microscope.
2. What are the five characteristics used to classify microorganisms?
   Answer
   Shape, size, nutritional requirements, habitat, and reproductive methods.
3. What are the five main types of microorganisms?
   Answer
   Bacteria, fungi, protozoa, algae, and viruses.
4. What is the shape of coccus bacteria?
   Answer
   Spherical.
5. How do bacteria reproduce?
   Answer
   Asexually through binary fission or sexually through conjugation.
6. What is the difference between autotrophic and heterotrophic bacteria?
   Answer
   Autotrophic bacteria produce their own food (e.g., through photosynthesis or chemosynthesis), while heterotrophic bacteria obtain nutrients from external sources.
7. How do fungi obtain nutrients?
   Answer
   They can be saprophytic (feeding on dead organic matter) or parasitic (obtaining nutrients from living organisms).
8. What are the main shapes of bacteria?
   Answer
   Spherical (coccus), rod-like (bacillus), spiral, or comma-shaped.
9. How do protozoa reproduce?
   Answer
   Through binary fission or conjugation.
10. What is the main nutritional mode of algae?
    Answer
    Algae are autotrophic and use chlorophyll for photosynthesis.
11. Why are viruses considered unique among microorganisms?
    Answer
    They can only reproduce within a host cell and do not require food.
12. What is normal flora?
    Answer
    Normal flora refers to microorganisms that naturally live in or on humans and animals.
13. Name two benefits of normal flora.
    Answer
    Aiding digestion and producing vitamins.
14. Where is normal flora most commonly found in the human body?
    Answer
    In the digestive tract.
15. How can antibiotics disrupt normal flora?
    Answer
    Antibiotics can kill beneficial bacteria, leading to an imbalance in normal flora.
16. What are the five factors influencing microbial growth?
    Answer
    Nutrients, moisture, pH level, light, and temperature.
17. Why is moisture important for microbial growth?
    Answer
    Microorganisms need water for metabolic activities and reproduction.
18. How does temperature affect microbial growth?
    Answer
    Most microorganisms grow best at temperatures between 35°C and 40°C.
19. How does pH level affect microorganisms?
    Answer
    Most microorganisms thrive at a neutral pH, but some prefer acidic or alkaline conditions.
20. Why do some microorganisms require light while others grow better in the dark?
    Answer
    Algae need light for photosynthesis, while other microbes, such as certain bacteria, thrive in dark environments.

Explanation Questions

1. Why do bacteria reproduce rapidly under ideal conditions?
   Answer
   Bacteria reproduce through binary fission, a quick and efficient process where one cell divides into two identical cells. If conditions such as nutrients, temperature, and moisture are optimal, they can multiply rapidly.
2. What is the difference between saprophytic and parasitic fungi?
   Answer
   Saprophytic fungi decompose dead organic matter, while parasitic fungi obtain nutrients from living hosts, sometimes causing diseases.
3. How does normal flora prevent the colonization of pathogens?
   Answer
   Normal flora competes with harmful bacteria for space and nutrients, producing substances that inhibit pathogen growth and stimulating the immune response.
4. Why do viruses require a host cell to reproduce?
   Answer
   Viruses lack cellular structures and metabolic machinery, so they must infect a host cell and use its resources to replicate.
5. How do algae contribute to the environment?
   Answer
   Algae produce oxygen through photosynthesis, serve as a food source in aquatic ecosystems, and help in carbon fixation.
6. How do changes in temperature affect microbial growth?
   Answer
   Microbes have optimal temperature ranges for growth. Extreme temperatures can slow growth, kill cells, or cause them to form spores for survival.
7. What happens when the pH level of an environment is too acidic or too alkaline for a microorganism?
   Answer
   Microorganisms may be unable to carry out essential metabolic processes, leading to slowed growth or death.
8. Why do antibiotics sometimes lead to digestive problems?
   Answer
   Antibiotics kill both harmful and beneficial bacteria in the digestive tract, disrupting normal digestion and leading to side effects like diarrhea.
9. How does moisture availability influence microbial survival and reproduction?
   Answer
   Microorganisms require moisture for essential metabolic processes, nutrient absorption, and reproduction. Without sufficient water, many microbes enter a dormant state or die, while in high-moisture environments, they can grow and multiply rapidly.
10. How can understanding microbial growth factors help in controlling harmful microorganisms?
    Answer
    By knowing the factors that influence microbial growth, such as temperature, pH, moisture, and nutrients, scientists and healthcare professionals can develop methods to control harmful microbes, such as refrigeration to slow bacterial growth, sterilization to eliminate pathogens, and pH adjustments to prevent contamination.