Microorganisms Friend and Foe in One shot | NCERT Class 8 Science Chapter 2 | BYJU'S - Class 8

BYJU'S - Class 6, 7 & 8・2 minutes read

Microorganisms are diverse, with examples like bacteria, fungi, protozoa, algae, and viruses found in various environments. Understanding their roles, benefits, and potential harms is crucial for health and industry, including topics like antibiotics, vaccines, food preservation, and the nitrogen cycle.

Insights

  • Microorganisms, including bacteria, fungi, protozoa, algae, and viruses, are tiny organisms found everywhere and can be harmful or beneficial, with bacteria having various shapes like bacilli, cocci, vibrio, and spirula.
  • Antibiotics and vaccines play crucial roles in combating diseases caused by pathogens, with antibiotics directly killing pathogens and vaccines stimulating the body's immune response, emphasizing the importance of completing antibiotic courses under medical supervision to prevent resistance and safeguarding overall health through proper vaccination and disease prevention measures.

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Recent questions

  • What are microorganisms?

    Microorganisms are tiny organisms not visible to the naked eye, requiring a microscope for observation. They are found everywhere, including air, water, soil, and extreme conditions like hot springs or snowy mountains. Classification includes bacteria, fungi, protozoa, algae, and viruses.

  • How do bacteria reproduce?

    Bacteria reproduce through fragmentation, not diffusion. They can be categorized based on their shape, such as bacilli (rod-shaped), cocci (spherical), vibrio, and spirula. An example of spirula bacteria is Leptospira.

  • What is the role of beneficial microbes?

    Beneficial microbes play essential roles in various industries like food, medical, and waste management/environment. For example, Lactobacillus bacteria convert milk to curd by converting lactose to lactic acid, aiding in the fermentation process.

  • What is the difference between antibiotics and vaccines?

    Antibiotics are chemical substances that kill or inhibit the growth of disease-causing microbes, while vaccines are biological preparations made of dead or weakened microbes to stimulate an immune response. Antibiotics directly target pathogens, while vaccines prompt the body to produce necessary cells to fight off pathogens.

  • How can food be preserved?

    Food preservation techniques include chemical methods like adding sodium metabisulfite, using salt and sugar, and pickling with oil and vinegar to prevent spoilage. Pasteurization involves heating milk to high temperatures and then cooling it to eliminate microbes, ensuring safety. Refrigeration and freezing are also used for food preservation.

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Summary

00:00

"Microorganisms: Tiny, Diverse, Harmful or Beneficial"

  • Microorganisms are the focus of the class, part of a mission to excel in exams within 45 days.
  • Microorganisms are tiny organisms not visible to the naked eye, requiring a microscope for observation.
  • Microorganisms are found everywhere, including in air, water, soil, and extreme conditions like hot springs or snowy mountains.
  • Classification of microorganisms includes bacteria, fungi, protozoa, algae, and viruses.
  • Bacteria come in various shapes like bacilli, cocci, vibrio, and spirula.
  • Fungi, such as yeast and mushrooms, grow on dead and decaying matter.
  • Protozoa examples include amoeba and paramecium.
  • Algae, primarily aquatic, include examples like chlamydomonas and giant kelp.
  • Viruses are not considered living organisms as they depend on host cells for replication.
  • Microorganisms can be harmful or beneficial, with a balance between good and harmful microbes.

15:31

Microbial Classification, Reproduction, and Applications

  • Bacteria can be categorized based on their shape: bacillus (rod-shaped), cocci (spherical), vibrio, and spirula.
  • Leptospira is an example of spirula bacteria.
  • Bacteria reproduce through fragmentation, not diffusion.
  • Beneficial microbes can be categorized into three industries: food, medical, and waste management/environment.
  • Lactobacillus bacteria convert milk to curd by converting lactose to lactic acid.
  • Curd formation involves structural changes in proteins due to lactic acid.
  • Inoculum is a substance containing microbes added to initiate growth.
  • Yeast aids in fermentation by breaking down sugars into alcohol and carbon dioxide.
  • Fermentation is the conversion of sugar into alcohol by microorganisms.
  • Antibiotics are chemical substances from microorganisms that kill or inhibit the growth of disease-causing microbes.

31:09

"Antibiotics, Vaccines, and Disease Prevention"

  • Antibiotics should only be taken under the prescription of a medical expert or doctor to avoid negative consequences.
  • Completing the full course of antibiotics is crucial to prevent the development of resistance in disease-causing pathogens.
  • Stopping antibiotics prematurely can lead to bacteria developing resistance against the medication.
  • Overusing antibiotics can harm the body's healthy microbes, affecting overall health.
  • Vaccines are biological preparations made of dead or weakened microbes to stimulate an immune response.
  • Antibodies are y-shaped proteins produced in response to pathogens to strengthen immunity.
  • Vaccines introduce dead or weakened microbes to activate the body's defense system against pathogens.
  • Antibiotics directly kill pathogens, while vaccines prompt the body to produce necessary cells to fight off pathogens.
  • Diseases are caused by pathogens, which are disease-causing microbes.
  • Communicable diseases can spread from an infected individual to a healthy person through various modes of transmission like air droplets, contaminated water, and vectors.

47:18

Food Preservation Techniques and Nitrogen Cycle Summary

  • Food preservation techniques include chemical methods like adding sodium metabisulfite, using salt and sugar, and pickling with oil and vinegar to prevent food spoilage.
  • Pasteurization involves heating milk to high temperatures and then cooling it to eliminate microbes, ensuring milk safety.
  • Proper storing and packaging techniques enhance the shelf life of food products.
  • The nitrogen cycle involves converting atmospheric gaseous nitrogen into a soluble form through nitrogen fixation, which can be physical (lightning) or biological.
  • Plants take up nitrogenous compounds produced through nitrogen fixation, which are then consumed by animals, eventually returning to the soil through decomposition.
  • Refrigeration and freezing are methods used to control temperature for food preservation, with freezing going below zero and refrigeration typically between 7-16 degrees Celsius.
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