NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

Class 8 Science Chapter 2 Microorganisms Friend and Foe:- Here are the NCERT Solutions for Class 8 Science Chapter 2: Microorganisms: Friend and Foe. These solutions are designed to assist students in answering the exercise questions from the NCERT Class 8 textbook. They offer comprehensive answers to each exercise question and include a range of question types, such as fill-in-the-blanks, match-the-following, true/false, and descriptive questions from Chapter 2 of the NCERT Class 8 textbook. Get the class 8 science chapter 2 question answer below.

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

Get the Science Class 8 Chapter 2 Solutions below:-

1. Fill in the blanks.

(a) Microorganisms can be seen with the help of a ____________.

(b) Blue-green algae fix __________ directly from the air and enhance the fertility of the soil.

(c) Alcohol is produced with the help of __________.

(d) Cholera is caused by __________.

Answer:

a) Microscope

b) Nitrogen

c) Yeast

d) Bacteria- Vibrio cholera

Check out: NCERT Solutions for Class 8 Science Chapter 1

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

Answer:

a) (ii) alcohol

b) (ii) Streptomycin

c) (i) female Anopheles mosquito

d) (ii) housefly

e) (iii) growth of yeast cells

f) (iii) fermentation

Read More: NCERT Solutions for Class 8 Science Chapter 3

3. Match the organisms in Column A with their action in Column B.

Sol:-

4. Can microorganisms be seen with the naked eye? If not, how can they be seen?

Answer:-  Microorganisms are generally not visible to the naked eye due to their minuscule size. These tiny organisms, including bacteria, viruses, fungi, and protozoa, are often only a few micrometres or nanometers in length. For comparison, a micrometre is one-millionth of a meter, and a nanometer is one-billionth.

To view microorganisms, specialized instruments known as microscopes are used. Microscopes can magnify objects many times their actual size, allowing us to see details that are otherwise invisible. 

5. What are the major groups of microorganisms?

Answer:- The major groups of microorganisms are as follows:

• Bacteria

• Fungi

• Protozoans

• Algae

• Viruses

6. Name the microorganisms which can fix atmospheric nitrogen in the soil.

Answer:- Rhizobium

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7. Write 10 lines on the usefulness of microorganisms in our lives.

1. Answer:- Microorganisms play a crucial role in decomposing dead organic matter from plants and animals, breaking it down into simple substances that are then reused by other organisms. This process helps in cleaning up the environment by degrading harmful and smelly substances.

2. In the production of food items, microorganisms are essential. For instance, curd is made by the bacterium Lactobacillus, which ferments milk into curd. Similarly, bacteria and yeast are involved in making cheese, and pickles, and in the fermentation of rice idlis and dosa batter.

3. Yeast is particularly useful in the baking industry. It reproduces quickly and produces carbon dioxide during respiration, which makes dough rise and increases its volume. This process is used to make bread, pastries, and cakes.

4. Microorganisms are also employed in the large-scale production of alcohol, wine, and vinegar (acetic acid).

5. Antibiotics, which are critical for treating bacterial infections, are derived from bacteria and fungi.

6. Some bacteria can fix atmospheric nitrogen, enriching soil fertility and supporting plant growth.

7. Microorganisms are used in producing vaccines to protect against various diseases.

8. Write a short paragraph on the harmful effects of microorganisms.

Answer:- Microorganisms can have several harmful effects on plants, animals, and humans. They can cause diseases, such as cholera in humans, which is caused by the bacterium Vibrio cholerae, and foot-and-mouth disease in animals, caused by a virus. Additionally, microorganisms can spoil food by decomposing it, leading to foodborne illnesses and food poisoning. They can also damage materials like leather and clothes, causing further problems. Overall, while microorganisms play many beneficial roles, they can also pose significant threats to health and property.

9. What are antibiotics? What precautions must be taken while taking antibiotics?

Answer:- Chemical agents that kill or inhibit the growth of disease-causing microorganisms are known as antibiotics. It is important to use antibiotics only under the guidance of a qualified doctor and to complete the full course of treatment as prescribed.

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Class 8 Science Chapter 2 Summary

Microorganisms Friend and Foe Class 8 includes the fascinating world of microorganisms, which are tiny organisms that are not visible to the naked eye. The chapter covers the various types of microorganisms, including bacteria, fungi, protozoa, and viruses, and highlights their roles in both beneficial and harmful processes.

1. Types of Microorganisms: The chapter introduces different microorganisms, detailing their characteristics and examples. Bacteria, fungi, protozoa, and viruses are discussed, emphasising their diverse forms and functions.

2. Beneficial Uses of Microorganisms: Microorganisms play crucial roles in various beneficial processes. They are involved in the production of food items like curd, cheese, and pickles, and they assist in fermentation processes for making idlis and dosas. Additionally, microorganisms are used in large-scale production of alcohol, wine, and vinegar, and are essential in producing antibiotics and vaccines. They also help in enriching the soil by fixing nitrogen and decomposing dead organic matter, aiding in waste recycling.

3. Harmful Effects of Microorganisms: While microorganisms have many benefits, they can also be harmful. They can cause diseases in humans, animals, and plants. Examples include cholera caused by Vibrio cholerae and foot-and-mouth disease caused by a virus. Microorganisms can spoil food, damage materials like leather and clothes, and contribute to food poisoning.

4. Antibiotics: The chapter explains that antibiotics are chemical agents used to kill or inhibit the growth of harmful microorganisms. It is important to use antibiotics responsibly, only under medical advice, and to complete the prescribed course to prevent resistance and ensure effectiveness.

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Microorganisms Friend and Foe Class 8 FAQs

Q1. What are microorganisms?

Ans. Microorganisms are tiny living organisms that are not visible to the naked eye. They include bacteria, fungi, protozoa, and viruses.

Q2. What roles do microorganisms play in our environment?

Ans. Microorganisms can have both beneficial and harmful roles. Beneficial roles include aiding in decomposition, enriching soil, producing food items (like curd and cheese), and being used in antibiotics and vaccines. Harmful roles include causing diseases and spoiling food and materials.

Q3. How do microorganisms help in making curd?

Ans. The bacterium Lactobacillus ferments milk to produce curd. It multiplies in milk, causing it to thicken and turn into curd.

Q4. What is the role of microorganisms in fermentation?

Ans. Microorganisms such as yeast are used in fermentation processes. For example, yeast helps in the production of bread, pastries, and idlis by producing carbon dioxide, which makes the dough rise.

Q5. How do microorganisms contribute to soil fertility?

Ans. Some bacteria can fix atmospheric nitrogen into a form that plants can use, thereby enriching the soil and increasing its fertility.