Unit: Microorganisms (Study Notes) 8th std - NMMS
Here is the comprehensive study note guide for the "Microorganisms" unit, cleaned and formatted for your NMMS and TNPSC exam preparation.
Unit: Microorganisms (Study Notes)
I. Introduction to Microorganisms
Definition: Organisms that can only be seen with the help of a microscope are called microorganisms. They are measured in microns.
Study of Fungi: Mycology.
Study of Algae: Algology or Phycology.
Study of Protozoa: Protozoology.
II. Classification and Structure
1. Bacteria
Nature: Prokaryotic (single-celled, no distinct nucleus).
Nutrition:
Photosynthetic: Make their own food (e.g., Cyanobacteria).
Chemosynthetic: Use chemicals like ammonia and hydrogen sulfide (e.g., bacteria in harsh environments).
Symbiotic: Live in relationships with other organisms (e.g., E. coli in the human intestine).
Reproduction: Fission (Binary and Multiple).
Classification by Flagella (Flagellation):
Monotrichous: Single flagellum at one end.
Lophotrichous: Tuft of flagella at one end.
Amphitrichous: Tuft of flagella at both ends.
Peritrichous: Flagella all around (e.g., E. coli).
Atrichous: No flagella (e.g., Corynebacterium diphtheriae).
2. Fungi
Nature: Eukaryotic, lack chlorophyll, grow in dark environments.
Types:
Unicellular: e.g., Yeast.
Multicellular: e.g., Penicillium, Mushrooms.
Yeast (Unicellular Fungi):
Shape: Ovoid.
Respiration: Anaerobic.
Reproduction: Budding.
Fermentation: Aided by the enzyme zymase.
Structure: Contains cell wall, nucleus, vacuoles, and glycogen/oil globules.
3. Algae
Nature: Simple plant-like eukaryotes, autotrophic (contain chlorophyll). Known as "grass of water".
Types:
Unicellular: e.g., Chlamydomonas (1 micron to 50 meters range).
Multicellular: e.g., Sargassum.
Chlamydomonas (Unicellular Algae):
Habitat: Fresh water.
Shape: Oval, spherical, or pyriform (pear-shaped).
Motility: Two flagella at the anterior end for locomotion.
Organelles: Cup-shaped chloroplast with a nucleus inside, tiny red eyespot (stigma) on the chloroplast, two contractile vacuoles for excretion.
Cell Wall: Made of cellulose.
4. Protozoa
Meaning: Greek 'protos' (first) + 'zoan' (animal).
Nature: Single-celled eukaryotes.
Classification by Locomotion:
Ciliates: Move by cilia (e.g., Paramecium).
Flagellates: Move by flagella (e.g., Euglena).
Pseudopods: Move by pseudopodia (e.g., Amoeba).
Sporozoans: Parasites (e.g., Plasmodium).
Amoeba:
Locomotion: Pseudopodia ("false feet") which are extensions of the cell membrane.
Feeding: Engulfs prey (algae) to form food vacuoles.
Excretion: Contractile vacuoles.
Reproduction: Fission and sporulation.
5. Prions and Virions
Prions: Mutated, harmless proteins that lack DNA/RNA. They affect brain/neural tissue.
Examples: Creutzfeldt-Jakob disease, Kuru (associated with cannibalism).
Virions: An entire virus particle outside the cell (extracellular). Consists of a protein capsid (shell) and a nucleic acid core (RNA or DNA).
III. Uses of Microorganisms (Beneficial)
1. Medicine
Antibiotics: Substances produced by living organisms toxic to others.
Penicillin: Discovered by Sir Alexander Fleming (1928) from the fungi Penicillium chrysogenum. Used for tetanus and diphtheria.
Streptomycin: Obtained from Streptomyces bacteria; cures plague.
Vaccines: Prepared from dead/weakened microbes.
Edward Jenner: First to discover the Smallpox vaccine and coined the term "vaccination".
MMR Vaccine: Measles, Mumps, Rubella.
BCG Vaccine: Bacille Calmette Guerin for Tuberculosis.
2. Agriculture
Natural Fertilizer: Microbes (decomposers) break down waste into nitrates/nutrients.
Nitrogen Fixation:
Rhizobium: Bacteria in root nodules of leguminous plants that fix atmospheric nitrogen as nitrates.
Cyanobacteria (Nostoc): Free-living bacteria in soil that fix nitrogen.
Bio-control Agents: Used to protect crops from pests.
Bacillus thuringiensis (Bt cotton): Controls insects.
Trichoderma (Fungi): Protects roots and controls plant pathogens.
Baculoviruses: Attack insects and arthropods.
3. Industry
Sewage Treatment:
Aerobic: Nitrobacter species consume organic matter.
Anaerobic: Methanobacterium used in sewage treatment.
Biogas Production: Methanogens (anaerobic bacteria) break down waste to produce Methane, CO2, and Hydrogen.
Alcohol/Wine: Yeast ferments sugars in grapes (wine) or rice/barley (beer).
Retting (Flax/Linen): Bacteria like Pseudomonas aeruginosa loosen stem fibers to make linen thread.
Tanning: Bacteria make animal skin soft and pliable.
4. Daily Life
Bread/Cakes: Yeast produces CO2, making dough rise. Chlorella (green algae) is added to enrich bread with nutrients.
Curd/Cheese: Lactobacillus bacteria turn milk Lactose into Lactic acid, thickening the milk.
Human Intestine:
Lactobacillus acidophilus: Aids digestion and fights harmful organisms.
E. coli: Synthesizes Vitamin K and Vitamin B complex.
IV. Food Preservation Techniques
1. Traditional Techniques
Fermentation: Microbial conversion of starch/sugar to alcohol.
Pickling: Preserving in edible antimicrobial liquid.
Chemical: Vinegar, alcohol, vegetable oil.
Fermentation: Bacteria produce lactic acid.
Boiling: Kills microbes (e.g., Milk, Water).
Sugaring: Antimicrobial syrup for fruits (Apples, Pears, Peaches).
2. Modern Techniques
Pasteurization: Invented by Louis Pasteur (1862) for milk.
Process: Heat milk to 70°C, then cool to 10°C.
Probiotics: Live food supplements (yoghurt) like Lactobacillus acidophilus and Bifidobacterium bifidum.
Benefits: Decrease colon cancer risk, decrease cholesterol absorption, prevent diarrhea.
V. Harmful Microorganisms (Diseases)
1. Plant Diseases
| Disease | Microorganism | Type | Mode of Transmission | Symptoms |
| Citrus Canker | Xanthomonas axonopodis | Bacteria | Air, Water | Lesions on leaves, stems, fruit |
| Potato Blight | Phytophthora infestans | Fungi | Air | Brown lesions on tubers |
2. Animal Diseases
| Disease | Microorganism | Type | Mode of Transmission | Preventive/Treatment |
| Anthrax | Bacillus anthracis | Bacteria | Contaminated soil/food | Anthrax vaccine |
| Foot & Mouth | Aphthovirus | Virus | Air, animal vectors | FMD vaccine |
3. Human Diseases
| Disease | Microorganism | Type | Mode of Transmission | Preventive/Treatment |
| Tuberculosis | Mycobacterium tuberculosis | Bacteria | Air, Sputum | BCG Vaccine |
| Cholera | Vibrio cholerae | Bacteria | Contaminated food/water, Flies | Anti-cholera vaccine |
| Common Cold | Influenza | Virus | Air | Isolation |
| Rabies | Rhabdoviridae | Virus | Animal bite | Anti-rabies vaccine |
| Amoebic Dysentery | Entamoeba histolytica | Protozoa | Food, water, flies | Metronidazole antibiotic |
| Malaria | Plasmodium | Protozoa | Female Anopheles mosquito | Quinine, Chloroquine |
VI. Important Exam Key Points (Dates & Names)
1928: Sir Alexander Fleming discovered Penicillin.
1862: Louis Pasteur invented Pasteurization.
Edward Jenner: Discovered Smallpox vaccine.
Bactericides: Copper-based ones treat Citrus Canker.
Prions: Cause Kuru and Creutzfeldt-Jakob disease.
Pseudopodia: Latin for "false feet".
Bacteria shapes: Unicellular algae shapes are spherical, rod, spindle; Bacteria are classified by flagella.
Here are 50 multiple-choice questions (MCQs) based on the "Microorganisms" unit to help with your NMMS and TNPSC exam preparation.
Topic: Introduction & Classification
1. Microorganisms are measured in units called:
a) Centimeters
b) Millimeters
c) Microns
d) Meters
Answer: c) Microns
2. The study of Fungi is known as:
a) Phycology
b) Mycology
c) Protozoology
d) Bacteriology
Answer: b) Mycology
3. Which of the following is a prokaryotic organism?
a) Yeast
b) Algae
c) Bacteria
d) Protozoa
Answer: c) Bacteria
4. Bacteria that lack flagella are called:
a) Monotrichous
b) Peritrichous
c) Atrichous
d) Lophotrichous
Answer: c) Atrichous
5. E. coli bacteria is an example of which flagellation type?
a) Monotrichous
b) Amphitrichous
c) Peritrichous
d) Atrichous
Answer: c) Peritrichous
6. Which bacteria has a tuft of flagella at one end?
a) Lophotrichous
b) Amphitrichous
c) Atrichous
d) Peritrichous
Answer: a) Lophotrichous
7. Algae are known as:
a) Grass of land
b) Grass of water
c) Flowers of ocean
d) Weeds of water
Answer: b) Grass of water
8. The study of Algae is called:
a) Mycology
b) Algology or Phycology
c) Zoology
d) Botany
Answer: b) Algology or Phycology
9. Chlamydomonas moves using:
a) Cilia
b) Pseudopodia
c) Flagella
d) Fimbriae
Answer: c) Flagella
10. The cup-shaped chloroplast is found in:
a) Volvox
b) Chlamydomonas
c) Sargassum
d) Ulothrix
Answer: b) Chlamydomonas
Topic: Fungi & Protozoa
11. Yeast reproduces by:
a) Binary fission
b) Spore formation
c) Budding
d) Fragmentation
Answer: c) Budding
12. The enzyme in yeast that aids in fermentation is:
a) Amylase
b) Zymase
c) Lactase
d) Lipase
Answer: b) Zymase
13. Which of the following is a multicellular fungus?
a) Yeast
b) Chlamydomonas
c) Penicillium
d) Amoeba
Answer: c) Penicillium
14. Protozoa means:
a) First animal
b) First plant
c) False feet
d) Single cell
Answer: a) First animal
15. Which organelle helps Amoeba in osmoregulation (excretion)?
a) Food vacuole
b) Contractile vacuole
c) Nucleus
d) Pseudopodia
Answer: b) Contractile vacuole
16. Paramecium moves with the help of:
a) Flagella
b) Pseudopodia
c) Cilia
d) Fins
Answer: c) Cilia
17. Which protozoan is a parasite causing Malaria?
a) Euglena
b) Plasmodium
c) Amoeba
d) Paramecium
Answer: b) Plasmodium
18. Euglena is classified as a:
a) Ciliate
b) Sporozoan
c) Flagellate
d) Pseudopod
Answer: c) Flagellate
Topic: Viruses & Prions
19. A virus particle found outside the cell is called a:
a) Prion
b) Virion
c) Capsid
d) Nucleoid
Answer: b) Virion
20. Prions differ from viruses because they lack:
a) Protein
b) DNA or RNA
c) Ability to infect
d) Shape
Answer: b) DNA or RNA
21. Kuru disease is associated with:
a) Mosquito bites
b) Cannibalism
c) Contaminated water
d) Air pollution
Answer: b) Cannibalism
22. The protein coat of a virus is called:
a) Cell wall
b) Membrane
c) Capsid
d) Envelope
Answer: c) Capsid
Topic: Uses of Microorganisms (Medicine & Agriculture)
23. Who discovered Penicillin?
a) Edward Jenner
b) Louis Pasteur
c) Sir Alexander Fleming
d) Robert Koch
Answer: c) Sir Alexander Fleming
24. Penicillin is obtained from:
a) Bacteria
b) Algae
c) Fungi
d) Protozoa
Answer: c) Fungi
25. Which vaccine prevents Tuberculosis?
a) MMR
b) BCG
c) FMD
d) Polio
Answer: b) BCG
26. Who coined the term "Vaccination"?
a) Louis Pasteur
b) Alexander Fleming
c) Edward Jenner
d) Aristole
Answer: c) Edward Jenner
27. Rhizobium bacteria help in:
a) Fermentation
b) Nitrogen fixation
c) Curd formation
d) Bread making
Answer: b) Nitrogen fixation
28. Which free-living bacteria in soil fixes nitrogen?
a) E. coli
b) Cyanobacteria Nostoc
c) Lactobacillus
d) Salmonella
Answer: b) Cyanobacteria Nostoc
29. Bt cotton uses genes from which bacteria to control insects?
a) Bacillus anthracis
b) Bacillus thuringiensis
c) Rhizobium
d) Pseudomonas
Answer: b) Bacillus thuringiensis
30. Which fungi is used as a bio-control agent to protect roots?
a) Yeast
b) Trichoderma
c) Penicillium
d) Agaricus
Answer: b) Trichoderma
Topic: Industry & Daily Life
31. The bacteria used in the anaerobic treatment of sewage is:
a) Nitrobacter
b) Methanobacterium
c) E. coli
d) Lactobacillus
Answer: b) Methanobacterium
32. Which bacteria produces methane (biogas)?
a) Methanogens
b) Pathogens
c) Lactogens
d) Aerobes
Answer: a) Methanogens
33. The process of loosening stem fibers using bacteria is called:
a) Tanning
b) Retting
c) Fermentation
d) Pickling
Answer: b) Retting
34. Which bacteria helps in retting of Flax?
a) Pseudomonas aeruginosa
b) Lactobacillus
c) Vibrio cholerae
d) Salmonella
Answer: a) Pseudomonas aeruginosa
35. Which algae is added to bread dough to enrich it with nutrients?
a) Spirogyra
b) Chlorella
c) Volvox
d) Ulva
Answer: b) Chlorella
36. Lactobacillus converts lactose in milk into:
a) Citric acid
b) Lactic acid
c) Acetic acid
d) Alcohol
Answer: b) Lactic acid
37. E. coli in the human intestine synthesizes:
a) Vitamin C
b) Vitamin K and B complex
c) Vitamin A
d) Vitamin D
Answer: b) Vitamin K and B complex
Topic: Food Preservation
38. Pasteurization involves heating milk to 70°C and cooling it to:
a) 0°C
b) 10°C
c) 20°C
d) 30°C
Answer: b) 10°C
39. Who invented Pasteurization?
a) Robert Koch
b) Louis Pasteur
c) Edward Jenner
d) Alexander Fleming
Answer: b) Louis Pasteur
40. Probiotics are typically found in:
a) Bread
b) Yoghurt
c) Wine
d) Vinegar
Answer: b) Yoghurt
Topic: Diseases
41. Citrus Canker is caused by:
a) Fungi
b) Virus
c) Bacteria (Xanthomonas axonopodis)
d) Algae
Answer: c) Bacteria (Xanthomonas axonopodis)
42. Potato blight disease is caused by:
a) Bacteria
b) Fungi (Phytophthora infestans)
c) Virus
d) Protozoa
Answer: b) Fungi (Phytophthora infestans)
43. Anthrax affects:
a) Only humans
b) Only animals
c) Both humans and animals
d) Plants
Answer: c) Both humans and animals
44. Foot and mouth disease is caused by:
a) Bacillus anthracis
b) Aphthovirus
c) Vibrio cholerae
d) Plasmodium
Answer: b) Aphthovirus
45. Which of the following is an airborne disease in humans?
a) Cholera
b) Tuberculosis
c) Malaria
d) Rabies
Answer: b) Tuberculosis
46. Cholera is caused by:
a) Mycobacterium tuberculosis
b) Vibrio cholerae
c) Entamoeba histolytica
d) Salmonella
Answer: b) Vibrio cholerae
47. Rabies is transmitted through:
a) Contaminated water
b) Air
c) Animal bite
d) Houseflies
Answer: c) Animal bite
48. Amoebic dysentery is caused by a:
a) Bacteria
b) Virus
c) Protozoa
d) Fungi
Answer: c) Protozoa
49. The vector for Malaria is:
a) Housefly
b) Female Anopheles mosquito
c) Male Anopheles mosquito
d) Cockroach
Answer: b) Female Anopheles mosquito
50. Which antibiotic is used to treat Tuberculosis?
a) Penicillin
b) Streptomycin
c) Paracetamol
d) Insulin
Answer: b) Streptomycin
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