Ncert Solutions For Class 8 Science Chapter 2 Microorganisms

Chapter 2 of Science Class 8 is “Micro Organisms – Friend and Foe”. Here are the NCERT Solutions for Class 8 Science Chapter 2

Class 8 Science Chapter 2 : Micro Organisms – Friend and Foe

Chapter 2 of Class 8 Science NCERT Text book is Micro Organisms – Friend and Foe. The end exercise of this chapter consists of a total of 9 question. These end exercise questions are related to Micro Organisms, types, atmospheric oxygen ,etc

Chapter 2 : Micro Organisms – Friend and Foe ( NCERT Solutions )

SubjectScience
Class 8 ( Class – VII )
Chapter Chapter 2 : Micro Organisms – Friend and Foe
Study MaterialNCERT Solutions ( End Exercise and Intext Questions )
Total Questions 7 Questions
Text BookScience NCERT Text Book ( Updated Syllabus)

NCERT Solutions For Class 8 Science Chapter 2 Micro Organisms – Friend and Foe

Q1. Fill in the Blanks
(a) Microorganisms can be seen with the help of a ________.
(b) Blue green algae fix _
______ directly from air and enhance fertility of soil.
(c) Alcohol is produced with the help of _______.
(d) Cholera is caused by ___
______.

Answer and Explanations:
(a) Microorganisms can be seen with the help of a microscope.
(b) Blue green algae fix nitrogen directly from air and enhance fertility of soil.
(c) Alcohol is produced with the help of yeast
(d) Cholera is caused by bacteria.

Q2. Tick the correct Answer
(a) Yeast is used in the production of
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen
Answer and Explanations: Option (ii) alcohol is the correct answer.
Yeast is used in production of alcohol.

(b) The following is an antibiotic
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast
Answer and Explanations: Option (ii) Streptomycin is the correct answer.
Streptomycin is an antibiotic

(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly
Answer and Explanations: Option (i) female Anopheles mosquito is the correct answer.
Carrier of malaria-causing protozoan is female Anopheles mosquito

(d) The most common carrier of communicable diseases is
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider
Answer and Explanations: Option (ii) housefly is the correct answer.
The most common carrier of communicable diseases is housefly

(e) The bread or idli dough rises because of
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading
Answer and Explanations: Option (iii) growth of yeast cells is the correct answer.
The bread or idli dough rises because of growth of yeast cells

(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection
Answer and Explanations: Option (iii) fermentation is the correct answer.
The process of conversion of sugar into alcohol is called fermentation

Q3. Match the organisms in Column A with their action in Column B

Column AColumn B
BacteriaFixing nitrogen
RhizobiumSetting of curd
LactobacillusBaking of bread
YeastCausing malaria
A protozoanCausing cholera
A VirusCausing AIDS
Producing antibodies

Answer and Explanation:
The Correct matches of the above points are given in the below table.

Column AColumn B
BacteriaCausing cholera
RhizobiumFixing nitrogen
LactobacillusSetting of curd
YeastBaking of bread
A protozoanCausing malaria
A VirusCausing AIDS

Q4. Can microorganisms be seen with the naked eye? If not, how can they be seen?
Answer and Explanation :
No , Microorganisms cannot be seen with the naked eyes. To see microbes like fungus, we require a magnifying glass. Moreover, other microbes can be seen with the help of a Microscope .

Q5. What are the major groups of microorganisms?
Answer and Explanation :
The basic classification of the Microbes is done on the basis of their sizes.
The major group of Microorganism is given below :
Bacteria
Protozoa
Algae
Fungi

Q6. Name the microorganisms which can fix atmospheric nitrogen in the soil.
Answer and Explanation :
Examples of those microbes which can fix the atmospheric nitrogen in the soil is given below .
Clostridium
Rhizobium
Azotabactor

Q7. Write 10 lines on the usefulness of microorganisms in our lives.
Answer and Explanation :
1. Yeast is used in bakery products.
2. Microbes decompose the waste material into the manure.
3. Microbes like Azotobacter helps to fix atmospheric nitrogen in soil.
4. Bacteria is used in the formation of food item likes pickles (achar)
5. Bacteria are also used in preparation of medicine.
6. Bacteria like lactobacillus helps to convert milk  into curd.
7. Yeast is used in the production of alcohol.
8. Bacteria are also used to make cheese.
9. Some Microbes are helpful in producing vaccine.
10. Microbes are used in biological treatment of waste.