NCERT Solutions | Class 8 Science Chapter 2 | Microorganisms: Friend and Foe

CBSE Solutions | Science Class 8

Check the below NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe Pdf free download. NCERT Solutions Class 8 Science were prepared based on the latest exam pattern. We have Provided Microorganisms: Friend and Foe Class 8 Science NCERT Solutions to help students understand the concept very well.

NCERT | Class 8 Science

NCERT Solutions Class 8 Science
Book:	National Council of Educational Research and Training (NCERT)
Board:	Central Board of Secondary Education (CBSE)
Class:	8th
Subject:	Science
Chapter:	2
Chapters Name:	Microorganisms: Friend and Foe
Medium:	English

Microorganisms: Friend and Foe | Class 8 Science | NCERT Books Solutions

You can refer to MCQ Questions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe to revise the concepts in the syllabus effectively and improve your chances of securing high marks in your board exams.

NCERT TEXTBOOK EXERCISES

NCERT Science book Class 8 Solutions PDF free download, Question 1.

Fill in the blanks.

Microorganisms can be seen with the help of a………………
Blue-green algae fix………….. directly from the air and enhance the fertility of the soil.
Alcohol is produced with the help of……………….
Cholera is caused by………………….

ncert class 8 science Chapter 2 question answer, Answer :

microscope
nitrogen
yeast
bacteria.

ncert science class 8 book, Question 2.

Tick the correct answer.
(a) Yeast is used in the production of
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen

cbse science class 8 solutions, Answer :

(ii) alcohol

(b) The following is an antibiotic
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast

ncert class 8 science Chapter 2 question answer, Answer :

(ii) Streptomycin

(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly

cbse science class 8 solutions, Answer :

(i) female Anopheles mosquito

(d) The most common carrier of communicable diseases is
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider

ncert class 8 science Chapter 2 question answer, Answer :

(ii) housefly

(e) The bread or idli dough rises because of
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading

cbse science class 8 solutions, Answer :

(iii) growth of yeast cells

(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection

ncert class 8 science Chapter 2 question answer, Answer :

(iii) fermentation.

ncert science class 8 Chapter 2, Question 3.

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

Column A

Column B

(i) Bacteria

(ii) Rhizobium

(iii) Lactobacillus

(iv)Yeast

(v) A protozoan

(vi) A virus

(a) Fixing nitrogen

(b) Setting of curd

(c) Baking of bread

(d) Causing malaria

(e) Causing cholera

(f) Causing AIDS

(g) Producing antibodies

cbse science class 8 solutions, Answer :

Column A	Column B
(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

ncert science class 8 pdf free download, Question 4.

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

ncert class 8 science Chapter 2 question answer, Answer :

No, we cannot see microorganisms with unaided eyes. They can be seen with the help of a microscope.

ncert science class 8 solutions, Question 5.

What are the major groups of microorganisms?

cbse science class 8 solutions, Answer :

Microorganisms are classified into four major groups based on their size. These are:

Bacteria
Fungi
Protozoa
Some algae.

Viruses are another type of microorganisms.
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe 1

ncert science class 8 textbook pdf, Question 6.

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

ncert class 8 science Chapter 2 question answer, Answer :

They are

Rhizobium
Azobhcter
blue-green algae (such as Anabaena and Nostoc), etc.

NCERT Solutions for Class 8 Science, Question 7.

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

cbse science class 8 solutions, Answer :

Microorganisms are useful for us in many ways e.g.,

the bacterium, lactobacillus converts milk into curd.
bacteria are also involved in the making of cheese.
Acetobacter acetic is used for the production of acetic acid from alcohol.
Yeast is used for the commercial production of alcohol and wine.
Antibiotics are manufactured by growing specific microorganisms.
Some bacteria fix atmospheric nitrogen and increase soil fertility.
Bacteria are used in the preparation of medicines like antibiotics and vaccines.
Bacteria are used in the preservation of pickles and many other food items.
Yeast is also used in the baking industry for making bread, pastries, and cakes.
They act as cleansing agents and decompose the waste products into manure.

NCERT Solutions for Class 8 Science Chapter 2, Question 8.

Write a short paragraph on the harmful effects of microorganisms.

ncert class 8 science Chapter 2 question answer, Answer :

The harms caused by microorganisms are as follows:

Many communicable diseases, such as cholera, common cold, chickenpox, tuberculosis, etc., are caused by microorganisms.
Malaria is caused by a microorganism called Plasmodium carried by the female Anopheles mosquito.
The Female Aedes mosquito acts as a carrier of the dengue virus.
Anthrax is a dangerous human and cattle disease caused by a bacterium called Bacillus anthracis.
Several microorganisms cause diseases in plants like wheat, rice, potato, sugarcane, orange, apple, etc., and reduce the yield of the crops.
Food poisoning is also caused by microorganisms. They make food poisonous by producing toxic substances in the food.

science class 8 Chapter 2, Question 9.

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

cbse science class 8 solutions, Answer :

The medicines, that kill or stop the growth of the disease-causing microorganisms, are called antibiotics. Streptomycin, tetracycline, erythromycin, etc. are some of the commonly known antibiotics which are made from fungi and bacteria.
The precautions to be taken while taking antibiotics are as follows :

These medicines should be taken only on the advice of a qualified doctor.
One must complete the course prescribed by the doctor.
If anybody takes antibiotics when not needed, his/her body may develop resistance against that antibiotic.