- Crop Production & Management
- Microorganisms – Friends & Foe
- Synthetic, Fibers & Plastic
- Materials – Metals and Non Metals
- Combustion and Flame
- Conservation Of Plants And Animals
- Coal & Petroleum
- Cell Structure And Functions
- Reproduction In Animals
- Reaching The Age Of Adolescence
- Force And Pressure
- Chemical Effects Of Electric Current
- Some Natural Phenomena
- Stars And The Solar System
- Pollution Of Air And Water
- Question Bank – Chapter 1 – Crop Production & Management
- Question Bank – Chapter 2 – Microorganisms
- Question Bank – Chapter 3 – Synthetic Fibres and Plastics
- Question Bank – Chapter 4 – Metals and Non Metals
- Question Bank – Chapter 5 – Coal & Petroleum
- Question Bank – Chapter 6 – Combustion and Flame
- Question Bank – Chapter 7 – Conservation of Plants and Animals
- Question Bank – Chapter 8 – Cell Structure & Functions
- Question Bank – Chapter 9 – Reproduction
- Question Bank – Chapter 10 – Reaching the age of adolescence
- Question Bank – Chapter 11 – Force and Pressure
- Question Bank – Chapter 12 – Friction
- Question Bank – Chapter 13 – Sound
- Question Bank – Chapter 14 – Chemical Effects of Electric Current
- Question Bank – Chapter 15 – Some Natural Phenomena
- Question Bank – Chapter 16 – Light
- Question Bank – Chapter 17 – Stars and Solar System
- Question Bank – Chapter 18 – Pollution of Air & Water
Question Bank – Chapter 2 – Microorganisms
Microorganisms: Friend and Foe
Qus 1. What are microorganisms or microbes?
Ans. There are other living organisms around us which we cannot see with eyes alone which are called microorganisms or microbes.
Qus 2. Name three uses of microorganisms?
Ans. Microorganisms are used for various purposes; they are used in the preparation of curd, bread and cake.
Qus 3. How bacteria can be used to increase soil fertility?
Ans. In agriculture bacteria is used to increase soil fertility by fixing nitrogen.
Qus 4. What do you mean by fermentation?
Ans. This process of conversion of sugar into alcohol is known as fermentation.
Qus 5. Who discovered the method of fermentation?
Ans. Louis Pasteur discovered fermentation in 1857.
Qus 6. What are antibiotics?
Ans. The source of some medicines are microorganisms, these medicines kill or stop the growth of the disease-causing microorganisms. Such medicines are called antibiotics.
Qus 7. Who discovered penicillin?
Ans. In 1929, Alexander Fleming discovered penicillin.
Qus 8. What is used for production of alcohol?
Ans. Yeast is used for commercial production of alcohol and wine.
Qus 9. Who discovered vaccine for small pox?
Ans. Edward Jenner discovered the vaccine for smallpox in 1798.
Qus 10. Name some diseases which can be prevented by vaccination?
Ans. Several diseases, including cholera, tuberculosis, smallpox and hepatitis can be prevented by vaccination.
Qus 11. What are pathogens?
Ans. Some of the microorganisms cause diseases in human beings, plants and animals. Such disease-causing microorganisms are called pathogens.
Qus 12. What are communicable diseases?
Ans. Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases.
Qus 13. What are preservatives?
Ans. Salts and edible oils are the common chemicals generally used to check the growth of microorganisms. Therefore they are called preservatives.
Qus 14. Who discovered pasteurization?
Ans. Louis Pasteur discovered pasteurization.
What makes the dough rise while preparing idli, dosa, bhaturas and dhoklas ?
How can be communicable diseases prevented ?
What is botulism? Name the organism causing it.
What are symbiotic or commensal bacteria and what is their significance for humans?
What is an antibiotic? Give any four examples of antibiotics.