NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe: Have you ever wondered why a stale bread kept in the dark and humid area grows white colored mesh over it? How the milk with a little curd kept in a hotter place by your mother turn into curd next morning? All these questions have been discussed in CBSE NCERT solutions for class 8 science chapter 2 Microorganisms Friends and Foe, it is due to the presence of microorganisms. This chapter deals with the role of microorganisms in our lives. After studying the chapter and solutions of NCERT for class 8 science chapter 2 Microorganisms Friends or Foe thoroughly, you will be able to attempt the exercise given in the textbook. Learning would be easier if you have CBSE NCERT solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe within your reach. You can also check out the solutions of NCERT for other chapters in science or even for other subjects by using the given links on this page.
Microorganisms are the smallest organisms that can not be seen with naked eyes. Now, must be wondering that if they can not be seen with naked eyes then how did we first get to know about them? It was mainly due to the invention of an instrument called the microscope. You will get to know about the structure and working of a microscope in NCERT grade 8 science chapter 2 microorganisms friends and foe.
There are five groups of microorganisms around us. These include
Among the above-given microorganisms, viruses are different from the rest. How? You will learn in class 8 science chapter 2.
NCERT Class 8 Science Chapter 2 Microorganisms Friend and Foe- Topics
The contents of NCERT science class 8 Chapter 2 are divided into certain topics and subtopics which are mentioned hereunder.
2.2 Where do microorganisms live
2.3 Microorganisms and us
2.4 Harmful microorganisms
2.5 NItrogen fixation
2.6 Nitrogen cycle
Q. Why do teachers keep telling us not to let water collect anywhere in our surroundings?
Ans. The teachers keep telling us to not let water collect anywhere because this water may act as a breeding site for insects that can cause diseases like dengue, malaria etc.
Q. The milk that comes in packets do not get spoiled because it is pasteurised. What do you understand by pasteurized milk?
Ans. The packeted milk is boiled at high-temperature for 15 to 30 seconds to kill the microbes present in it. This milk is called pasteurized milk and it does not get spoiled.
So, like these questions, you can solve more for examination purpose.
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe
Microorganisms: Friend and Foe Excercise:
Q.5. What are the major groups of microorganisms?
The major groups of microorganisms are as follows-
(i) Bacteria- unicellular organisms. most common examples of bacteria are Salmonella typhi, Rhizobium, Mycobacterium etc. Typhoid and tuberculosis (TB) are bacterial diseases.
(ii) Fungi- Multicellular organisms which feed on dead and deaying matter. Bread mould is common examples.
(iii) Protozoa- Unicellular organisms wihich are mostly parasitic. Organisms like Amoeba, Plasmodium etc are under this category. Dysentery and malaria are caused by protozoans.
(iv) Virus- Acellular organisms which reproduce only inside the cells of the host organism. These cause diseases like chicken pox and polio.
(v) Algae- They are unicellular or multicellular organism. Spirogyra, Chlamydomonas, Ulva are some of the examples of algae.
The microorganism that can fix atmospheric nitrogen in the soil are bacteria such as Rhizobium, and blue-green algae. These converted nitrogenous compounds can be easily used by plants for the plant protein synthesis and other purposes.
Q.7. Write 10 lines on the usefulness of microorganisms in our lives.
Microorganisms are useful for us in following ways-
- Microorganisms are used to increase the fertility of the soil by fixing the atmospheric nitrogen with the help of blue-green algae and Rhizobium.
- Antibiotics which are obtained from microorganisms are used to control the diseases.
- There are some bacteria which can turn nitrogen compounds found in the soil into nitrogen gas which is further released into the environment.
- Bacterium Lactobacillus reproduces in milk and promotes the formation of curd.
- Microorganisms especially yeast can be used for the industrial production of alcohol, wine and acetic acid (vinegar).
- Microbes are used to reduce pollution. example- bacteria and fungi break down the dead bodies and excreta to form inorganic compounds which are absorbed by plants
- Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume.Thus they have a use in making of bread
Q.8. Write a short paragraph on the harmful effects of microorganisms.
The harmful effects of microorganisms are given below-
- Microorganisms cause diseases in humans as well as animals. For example cholera and TB are caused by bacteria in humans.
- In plants also diseases are caused by microorganisms. For example, citrus canker in plants is caused by bacteria and rust of wheat is caused by fungi.
- Food poisoning is also caused by the microorganisms that spoils our food by producing some toxic substances. For example- when the bread is left in under moist condition gets spoilt by fungus.
Q.9. What are antibiotics? What precautions must be taken while taking antibiotics?
Antibiotics- These are medicines that kill or stop the growth of the disease-causing microorganisms. There are a lot of antibiotics which are produced with the help of bacteria and fungi. Streptomycin, tetracycline and erythromycin are some of the commonly known antibiotics which are made from fungi and bacteria.
Precautions that must be taken while using antibiotics-
- Antibiotics must be taken obly on the prescrition of a doctor.
- must finish the course prescribed by the doctor.
- An antibiotic should be taken in the right amount only. Antibiotics taken unnecessarily may kill beneficial bacteria in the body.
Q.10. What precautions must be taken while taking antibiotics?
Those medicines kill or stop the growth of the disease-causing microorganisms are called antibiotics. Antibiotics are
being produced from bacteria and fungi.
Precaution to be taken while using antibiotics-
- antibiotics should be taken only on the advice of a qualified doctor.
- must finish the course prescribed by the doctor.
- An antibiotic should be taken in the right amount. antibiotics taken unnecessarily may kill beneficial bacteria in the body.
NCERT solutions for class 8 science: chapter-Wise
NCERT Solutions For Class 8: Subject-Wise
How to use NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe?
- Now that you know the solutions of NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe and have understood the topics well, its time to put them to practice
- Check previous year questions from the board exam and see if you can apply the CBSE NCERT solutions of class 8 to them and know your preparation levels.
- If you have not really scored well, it's time to practice a bit more. If you have been able to answer the questions, it's time to move to NCERT solutions for class 8 science chapter 2 Microorganisms Friends and Foe as your aim is to really do well in those board exams.
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