Grade 8 | Science | Microorganisms Friends and foe | Free Tutorial | CBSE | ICSE | State Board

Summary

This module explores the world of microorganisms, classifying them into useful and harmful types. Useful microorganisms, like yeast and lactobacillus, play vital roles in food production, medicine, and nitrogen fixation. Harmful microorganisms, or pathogens, are responsible for diseases in humans, animals, and plants. The module also covers the methods of food preservation and highlights the importance of processes like pasteurization to prevent foodborne illnesses. Overall, it emphasizes the diverse roles microorganisms play in both aiding and harming life on Earth.

Takeaways

• 😀 Microorganisms are tiny organisms that cannot be seen with the naked eye and are classified into bacteria, fungi, protozoa, and algae.
• 😀 Microorganisms can either be helpful (friendly) or harmful (foes), and are found in various environments like water, soil, and hot springs.
• 😀 Friendly microorganisms, like yeast and Lactobacillus bacteria, are used in food production such as bread, curd, and alcoholic beverages.
• 😀 Microorganisms are essential in producing antibiotics and vaccines that help prevent diseases like cholera, tuberculosis, and smallpox.
• 😀 Nitrogen fixation is a vital process where microorganisms convert atmospheric nitrogen into ammonia, enriching soil fertility.
• 😀 Anaerobic bacteria are used to produce biogas, a renewable energy source made from methane, carbon dioxide, hydrogen, and hydrogen sulfide.
• 😀 Harmful microorganisms, known as pathogens, can cause diseases in humans, animals, and plants, and they spread through air, water, and food.
• 😀 Diseases like malaria are caused by pathogens carried by insects, such as mosquitoes transmitting Plasmodium parasites.
• 😀 Food can become contaminated by bacteria like Clostridium, Bacillus, and Staphylococcus, leading to food poisoning.
• 😀 Food preservation methods like pasteurization help prevent food spoilage by killing harmful microorganisms.
• 😀 Understanding the distinction between communicable (infectious) and non-communicable diseases is crucial, as communicable diseases spread from person to person.

Q & A

What are microorganisms and how are they classified?

Microorganisms, or microbes, are tiny organisms that cannot be seen with the naked eye. They are classified into four major groups: bacteria, fungi, protozoa, and algae. Viruses are also considered microorganisms.

What is the role of yeast in the food industry?

Yeast is used in the baking industry and at home for making bread, cakes, and pastries. It helps in fermentation, which causes dough to rise and gives baked goods their texture.

What are the benefits of lactobacillus bacteria?

Lactobacillus bacteria are useful in the production of curd from milk. They ferment the lactose in milk, turning it into lactic acid, which gives curd its consistency and taste.

How do microorganisms contribute to the production of antibiotics and vaccines?

Certain bacteria are used in the production of antibiotics and vaccines. These microorganisms produce substances that can fight diseases or stimulate immune responses, helping prevent illnesses such as cholera, tuberculosis, smallpox, and hepatitis.

What is nitrogen fixation, and why is it important?

Nitrogen fixation is the biological process in which atmospheric nitrogen is converted into ammonia, which plants can use as a nutrient. This process is carried out by specific bacteria and blue-green algae, and it enhances soil fertility.

What are harmful microorganisms, and how do they cause diseases?

Harmful microorganisms, known as pathogens, cause diseases in humans, animals, and plants. They can spread through air, water, or food, and cause infections such as malaria, cholera, and common cold.

What are communicable and non-communicable diseases?

Communicable diseases can be transferred from one person to another, such as through air or water (e.g., common cold, malaria). Non-communicable diseases cannot be spread between individuals (e.g., certain chronic illnesses).

How do mosquitoes contribute to the spread of diseases?

Female Anopheles mosquitoes are carriers of Plasmodium parasites, which cause malaria. Mosquitoes spread these pathogens by biting an infected person and then transmitting the disease to healthy individuals.

What are some common foodborne diseases caused by bacteria?

Foodborne diseases caused by bacteria include food poisoning from bacteria like Clostridium, Bacillus, and Staphylococcus, which can contaminate food if it is left exposed for too long.

How is milk preserved using microorganisms?

Milk is preserved through pasteurization, a process that uses heat to kill harmful microorganisms, extending the shelf life of milk and preventing it from spoiling.