Class 8: Microorganisms and Food Preservation

• Chapter 8 of the Class 8 curriculum is about microorganisms and their effects on humans, animals, and plants.
• Microorganisms can be useful for humans and animals, but harmful for plants.
• Pathogens are microorganisms that cause diseases, and they can enter the human body through contaminated food, water, or infected parasites.
• Communicable diseases can spread through infected parasites, contaminated food or water, or physical contact.
• Insects and animals can act as carriers for diseases, spreading them to humans.
• Food poisoning can occur when microorganisms present in food contaminate it and cause illness.
• Preservation methods like chemical preservation using sodium benzoate and sodium metabisulfite can extend the shelf life of food by inhibiting the growth of microorganisms.
• Salt and vinegar can also be used for preservation, as seen in the example of pickles.
• Post-pasteurization and poststerilization processes involve heating milk to a high temperature, then quickly cooling it to prevent harmful bacteria from growing.
• The process of pasteurization involves heating milk to 70 degrees Celsius for 15-30 seconds, then rapidly cooling it to store it safely.
• Poststerilized milk remains safe to consume for a few days due to harmful bacteria being killed off during the high-temperature treatment.- Six test tourism recommends storing food in tight containers or packets to prevent microbial attacks and food spoilage.
• Nitrogen fixation involves root nodules in legume plants where Rhizobium bacteria convert atmospheric nitrogen into a usable form for plants.
• Root nodules provide shelter for bacteria to convert atmospheric nitrogen into a usable form, benefiting plant growth.
• Plants utilize the converted nitrogen from bacteria for their growth, which later enters the food chain through animals and humans.
• Animals and humans cannot directly use atmospheric nitrogen but benefit from the converted usable form present in plants.
• Bacteria convert nitrogen compounds from dead animals or waste into gaseous nitrogen, completing the nitrogen cycle.
• The nitrogen cycle starts with atmospheric nitrogen, converts it into a usable form, and then back into atmospheric nitrogen, creating a continuous cycle.

Test your knowledge on microorganisms, pathogens, communicable diseases, food preservation methods, and the nitrogen cycle as covered in Chapter 8 of the Class 8 curriculum. Explore how microorganisms can be beneficial or harmful to humans, animals, and plants.