17 Questions
Which of the following microorganisms can contaminate food and water, leading to serious illnesses?
Salmonella
What type of infections can certain fungi cause in various parts of the body?
Athlete's foot
Why have some microorganisms become difficult to treat with antibiotics?
They are now resistant to antibiotics
Which viruses can spread quickly among people, causing illnesses like the common cold and influenza?
Influenza virus
How does understanding the diverse nature of microorganisms empower individuals according to the text?
To make informed decisions about personal hygiene
What does the flame front represent in combustion?
The region where the combustion occurs most rapidly
Why is understanding combustion processes important for engineers?
To design more efficient engines and devices
What region does the inner cone of a flame represent?
Region where gases mix with incoming air
In what controlled environments might students observe the burning of different fuels?
Laboratory settings
Why might students measure the height of flames during combustion experiments?
To estimate the amount of heat released
What is one benefit of studying combustion in NCERT Class 8 according to the text?
Grasping fundamental principles of chemistry, physics, and engineering
What is combustion?
A chemical reaction between fuel and oxygen producing heat and light
What role does oxygen play in combustion?
It supports the burning process by reacting with the fuel
Why is combustion important for daily activities like cooking and heating?
To produce energy in the form of heat and light
What is a flame?
An intense glowing plasma resulting from rapid oxidation of hydrocarbon gases
Which of the following is NOT part of a typical flame structure?
Solid core
Why do we see light in a flame during combustion?
As a result of rapid oxidation and incandescence of solid particles
Study Notes
NCERT Class 8 Science: Microorganisms - Friend or Foe?
In NCERT Class 8 Science, students are introduced to the fascinating world of microorganisms - tiny living beings that are too small to be seen with the naked eye. This introduction is crucial because it lays the foundation for understanding various aspects of life, including human health and disease, environmental science, and agriculture. In this unit, students learn about microorganisms from different perspectives - sometimes they can be beneficial while other times they may pose threats to our health and well-being. Here, we will explore these two facets of microorganisms by examining their role as both friends and foes.
Microorganisms as Friends
Microorganisms have been known to contribute significantly towards the progress of humankind since ancient times. Some of them play vital roles in maintaining balance in ecosystems. For example, bacteria found in soil help break down dead plants and animals, making nutrients available for other organisms. Similarly, some kinds of fungi help in breaking down waste materials and recycling nutrients back into the environment.
Moreover, microorganisms like yeast are used in baking bread and brewing alcoholic drinks. Probiotics, which are live beneficial bacteria and yeasts, are also important for digestive system health. These friendly microbes help maintain the body's natural defenses against pathogens, thereby supporting overall health.
Microorganisms as Foes
On the other hand, not all microorganisms are benign. Some can cause diseases in humans, animals, and plants. Bacteria such as Salmonella and Escherichia coli, for instance, can contaminate food and water, leading to serious illnesses. Viruses like the common cold virus and influenza virus can also spread quickly among people. Furthermore, certain types of fungi can lead to infections in various parts of the body, causing conditions like athlete's foot and ringworm.
Additionally, some microorganisms have become resistant to antibiotics, making it difficult to treat bacterial infections effectively. This resistance has posed significant challenges in modern medicine and healthcare.
Conclusion
In conclusion, microorganisms serve dual purposes in our lives - they can be both friends and foes. While some microbes help us in various ways, others can cause harm if left unchecked. Understanding the diverse nature of microorganisms helps us appreciate the complex interplay between life forms and their environments. This knowledge empowers us to make informed decisions about personal hygiene, sanitation, food preparation, and public health measures.
Explore the world of microorganisms in NCERT Class 8 Science, where students learn about the dual nature of these tiny living beings. Discover how some microorganisms are beneficial friends while others can be harmful foes, impacting human health, ecosystems, and agriculture.
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