Last Updated on February 21, 2025 by sanjjeett
The NCERT Solutions have been updated for 2024-2025 sessions, with the new NCERT Books. All questions are solved with detailed explanation of each and every questions. In this article, we are providing NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe. It is a part of NCERT Solutions for Class 8 Science series.
| Chapter | Microorganisms: Friend and Foe |
| Textbook | NCERT |
| Type of Material | NCERT Solutions |
| Format | Question-Answer Format |
| Class | 8 |
| Subject | Science |
| Useful for | Class 8 Studying Students |
| Session | 2024-25 |
| No. of Intext Questions | 9 |
| Exercise Questions | 7 |
| Solutions provided | Yes |
| Important Link | NCERT Solutions for Class 8 Science |
Microorganisms: Friend and Foe NCERT Solutions Class 8
NCERT Solutions for Class 8 Science Chapter 2, Microorganisms: Friend and Foe, offer clear, step-by-step answers to all textbook questions. Expertly crafted, these solutions simplify complex concepts, enhance understanding, and build confidence, helping students excel in their studies.
Intext Questions
Page-17
Q. 1. Boojho wants to know why certain living organisms are called micro-organisms or microbes.
Ans. The micro-organisms are so small in size that they cannot be seen with the naked eye and some of these can be seen only by microscope. That is why these are called micro-organisms.
Q. 2. Paheli saw that her mother added a little curd to warm milk to set curd for the next day. She is wondering, why?
Ans. Curd contains several micro-organisms, mainly the bacterium Lactobacillus, which promote the formation of curd. They start growing in milk and convert milk into curd.
Q. 3. Paheli wants to know why children/infants are given vaccination.
Ans. By vaccination, disease carrying microbes enters our body, the body produces antibodies to fight the invader. The body also remembers how to fight the microbe if it enters again. So, if dead or weakened microbes are introduced in a healthy body, the body fights and kills them by producing suitable antibodies. The antibodies remain in the body and we are protected from the disease-
causing microbes. This is how a vaccine works.
Page-23
Q. 4. How do you prevent the spread of communicable diseases?
Ans. We should keep a handkerchief on the nose while sneezing. It is better to keep distance from infected persons.
Q. 5. Paheli is wondering why teacher keeps telling them not to let water collect anywhere in the neighbourhood.
Ans. All mosquitoes breed in water. Hence by keeping the surroundings clean and dry, we can prevent mosquitoes from breeding. One should not let water collect anywhere viz., in coolers, tyres, flower-pot, etc.
Q. 6. Paheli wonders how food can become poisonous.
Ans. Food poisoning could be due to the consumption of food spoilt by some micro-organisms. Micro-organisms that grow on our food sometimes produce toxic substances. These make the food poisonous causing serious illness and even death.
Page-26
Q. 7. Boojho wants to know what is pasteurisation.
Ans. The milk is heated to 700C for 15 seconds to 30 seconds and then suddenly chilled and stored. By doing so, it prevents the growth of microbes. This process was discovered by Louis Pasteur. It is called Pasteurisation.
Exercise Questions
Q. 1. Fill in the blanks.
(a) Micro-organisms can be seen with the help of a __________.
(b) Blue green algae fix ___________directly from air to enhance fertility of soil.
(c) Alcohol is produced with the help of ___________.
(d) Cholera is caused by __________.
Ans. (a) Microscope, (b) Nitrogen, (c) Yeast, (d) Bacteria.
Q. 2. Tick the correct answer:
(a) Yeast is used in the production of:
(i) Sugar
(ii) Alcohol
(iii) Hydrochloric acid
(iv) Oxygen
(b) The following is an antibiotic:
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast
(c) Carrier of malaria-causing protozoan is:
(i) Female Anopheles mosquito
(ii) Cockroach
(iii) Housefly
(iv) Butterfly
(d) The most common carrier of communicable diseases is:
(i) Ant
(ii) Housefly
(iii) Dragonfly
(iv) Spider
(e) The bread or idli dough rises because of:
(i) Heat
(ii) Grinding
(iii) Growth of yeast cells
(iv) Kneading
(f) The process of conversion of sugar into alcohol is called:
(i) Nitrogen Fixation
(ii) Moulding
(iii) Fermentation
(iv) Infection
Ans. (a) (ii) Alcohol is produced by the action of yeast.
(b) (ii) Streptomycin is an antibiotic effective against tuberculosis.
(c) (i)Female Anopheles mosquito is the carrier of malaria.
(d) (ii) The most common carrier of communicable diseases is Housefly.
(e) (iii) Idli dough rises due to growth of yeast cells.
(f) (iii) Fermentation.
Q. 3. Match the organisms in column I with their action in column II.
| Column I | Column II |
| (i) Bacteria | (a) Fixing nitrogen |
| (ii) Rhizobium | (b) Setting of curd |
| (iii) Lactobacillus | (c) Baking of bread |
| (iv) Yeast | (d) Causing malaria |
| (v) A protozoan | (e) Causing cholera |
| (vi) A virus | (f) Causing AIDS |
| (g) Producing antibodies |
Ans. (i) (e), (ii) (a), (iii) (b), (iv) (c), (v) (d), (vi) (f)
| Column I | Column II |
| (i) Bacteria | (e) Causing cholera |
| (ii) Rhizobium | (a) Fixing nitrogen |
| (iii) Lactobacillus | (b) Setting of curd |
| (iv) Yeast | (c) Baking of bread |
| (v) A protozoan | (d) Causing malaria |
| (vi) A virus | (f) Causing AIDS |
Q. 4. Can micro-organisms be seen with the naked eye? If not, how can they be seen?
Ans. Micro-organisms cannot be seen with the naked eyes. They can be seen with the help of a micro-scope.
Q. 5. What are the major groups of micro-organisms?
Ans. Micro-organisms are divided into five major groups which are as follows:
(i) Bacteria: These are single celled organisms which are harmful, as they cause disease and some of them may be useful in vaccines.
(ii) Fungi: These are non-green plants which consume their food from the dead organic matter.
(iii) Protozoan: These are unicellular animals which cause diseases like malaria and dysentery.
(iv) Algae: These are photo-autotrophic organisms that may be unicellular or multicellular. They play an important role in medicines, agriculture, industry and as food.
(v) Viruses are also considered to be micro-organisms but are actually the connecting links between non-living and living organisms.
Q. 6. Name the micro-organisms which can fix atmospheric nitrogen in the soil.
Ans. Bacteria, like Rhizobium and blue green algae can fix atmospheric nitrogen in the soil.
Q. 7. Write 10 lines on the usefulness of micro-organisms in our lives.
Ans. Uses of micro-organisms:
(i) Micro-organisms are used in making of curd and bread.
(ii) Bacteria are also involved in the making of cheese, pickles and many other food items.
(iii) Acetobacter aceti bacteria is used for production of acetic acid from alcohol.
(iv) Yeast is used for commercial production of alcohol and wine.
(v) The antibiotics manufactured by growing specific micro-organisms are used to cure a variety of diseases.
(vi) Micro-organisms fix the nitrogen of atmosphere into soil giving rise to fertility of soil.
(vii) Micro-organisms decompose waste into simple materials and clean-up the atmosphere.
(viii) Micro-organisms decompose the dead organic varieties of plants and animals.
(ix) Vaccines are made by dead or weakened microbes.
(x) Certain microbes are also used in the biological treatment of sewage and industrial effluents.
Q. 8. Write a short paragraph on the diseases caused by micro-organisms.
Ans. Micro-organisms are also very harmful to us. They cause a number of diseases in humans as well as in other animals. Common cold, tuberculosis, measles, chicken pox, polio, cholera, typhoid, hepatitis-B, malaria are some common human diseases caused by microorganisms. Anthrax is a serious disease in animals caused by microbes. They also make food items unfit for use by food poisoning. They also spoil clothes and leather products. They also cause diseases in plants like blights in potatoes, sugarcanes, oranges, etc. They also reduce the crop production.
Q. 9. What are antibiotics? What precautions must be taken while taking antibiotics?
Ans. Antibiotics are tablets, capsules or injections which are used to kill or stop the growth of pathogens, i.e., disease causing microbes. Penicillin, tetracycline are the examples of antibiotics.
Precautions:
(i) It should be taken in proper dose only on the advice of qualified doctors.
(ii) Complete course prescribed by the doctor.
(iii) It should not be taken without any reason, or requirement.
(iv) Antibiotics taken unnecessarily may kill the beneficial bacteria in the body.
Related posts
| Microorganisms: Friend and Foe Case Study Questions | Microorganisms: Friend and Foe Assertion Reasoning |
Also check
- NCERT Solutions for Class 8 Science Chapter 8 Force and Pressure
- NCERT Solutions for Class 8 Science Chapter 7 Reaching the Age of Adolescence
- NCERT Solutions for Class 8 Science Chapter 6 Reproduction in Animals
- NCERT Solutions for Class 8 Science Chapter 5 Conservation of Plants and Animals
- NCERT Solutions for Class 8 Science Chapter 4 Combustion and Flame
- NCERT Solutions for Class 8 Science Chapter 3 Coal and Petroleum
- NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe
- NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management
🔗 Explore More: Find all NCERT solutions here → NCERT Solutions for Class 1 to 12
You may also like
Frequently Asked Questions (FAQs) on Microorganisms Friend and Foe Class 8 NCERT Solutions
Q1: What are NCERT Solutions?
A1: NCERT Solutions are detailed, step-by-step answers to the questions provided in the NCERT textbooks. They are designed to help students understand the concepts thoroughly and prepare effectively for their exams.
Q2: Why are NCERT Solutions important for students?
A2: NCERT Solutions are crucial for students because they offer clear explanations and step-by-step guidance on solving textbook problems. They help in building a strong foundation in each subject, making it easier for students to grasp complex concepts and perform well in their exams.
Q3: Are the NCERT Solutions available for free on Xam Content?
A3: Yes, all the NCERT Solutions on our website are available for free. We believe in making education accessible to all students, ensuring that everyone can benefit from our resources without any cost.
Q4: How can NCERT Solutions help in exam preparation?
A4: NCERT Solutions help in exam preparation by providing thorough explanations and solutions to textbook problems. They ensure that students understand the core concepts and are well-prepared for any type of question that may appear in their exams.
Q5:Â Are NCERT solutions enough for scoring good marks in Class 8 Science exams?
A5: Yes, NCERT solutions cover the entire syllabus prescribed by CBSE for Class 8 Science. If students thoroughly understand and practice these solutions, they can definitely score well in their exams. However, it’s also beneficial to supplement your studies with additional reference materials and practice questions. For various types of questions asked in social science exam, you can visit xamcontent.com.
