Economic Importance of Bacteria Short Answer Biology Class-9 ICSE Selina Publishers Part A

Economic Importance of Bacteria Short Answer Biology Class-9 ICSE Selina Publishers Solutions Chapter-9 Part A. Step By Step ICSE Selina Concise Solutions of Chapter-9 Economic Importance of Bacteria with Exercise-9A including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured/Application Questions Solved Visit official Website CISCE for detail information about ICSE Board Class-9.

Economic Importance of Bacteria Exe-9A Short Answer Biology Class-9 ICSE Concise Selina Publishers

Board ICSE
Publications Selina Publication
Subject Biology
Class 9th
Chapter-9 Economic Importance of Bacteria and Fungi
Book Name Concise
Topics Solution of C. Short Answer Type
Academic Session 2023-2024

C. Short Answer Type 

Economic Importance of Bacteria Class-9 Biology Concise Solutions  

Page 94

Question 1.

In what form bacteria may be present in the air?


In air, bacteria can be present in the form of spores.

Question 2.

Why is spore formation in bacteria not considered a form of reproduction?


Spore formation in bacteria cannot be considered as a form of reproduction as they can reproduce through asexual means only such as cell division or fission. The formation of spores in bacteria is only an escape tactic from unfavorable condition that is exhibited by them.

Question 3.

In what respect do you consider bacteria as simple organisms?


Bacteria are unicellular organisms that lack membrane bound cell organelles like chloroplast, mitochondria, etc. and even a well-defined nucleus is absent which states that they have a simpler cellular organization.

Question 4.

Define the terms :

(a) Antibiotics

(b) Antitoxins

(c) Serum

(d) Botulism

(e) Pasteurization


(a) Antibiotics — An antibiotic is a chemical substance produced by a living microorganism which can stop the growth of or kill some disease-producing bacteria and fungi.

(b) Antitoxins — Antitoxin is a substance produced in animal bodies which reacts with the poison (toxin) produced by the invading germs.

(c) Serum — Serum actually means blood plasma from which fibrinogen has been removed. It may contain numerous chemical substances including anti-bodies and antitoxins.

(d) Botulism — Botulism is a very serious food poisoning due to a special bacterium sometimes found in tinned or sealed foods.

(e) Pasteurization — Pasteurization is the process of food preservation, applied usually to milk. In this process, the milk is heated at 60°C for 30 minutes and then chilled quickly. It kills majority of bacteria.

Question 5.

Give two examples of each :

(a) Bacterial diseases of cattle

(b) Bacterial diseases in plants

(c) Bacterial diseases in humans

(d) Nitrifying bacteria

(e) Free living nitrogen-fixing bacteria found in soil


(a) Anthrax and Bovine tuberculosis

(b) Bacterial blight of cowpea and Black rot of mustard

(c) Cholera and Tuberculosis

(d) Nitrosomonas and Nitrobacter

(e) Azotobacter and Clostridium

Question 6.

Write the full forms of the following abbreviations:

(a) TAB

(b) BCG

(c) DNA

(d) GMO


(a) TAB — Typhoid-paratyphoid A and B

(b) BCG — Bacille Calmette-Guerin

(c) DNA — Deoxyribonucleic Acid

(d) GMO — Genetically Modified Organism

Question 7.

Give reasons :

(a) Every room in the house should get direct sunlight at least for a short time.

(b) Tinned and sealed food is not always safe to eat.


(a) Direct sunlight contains ultraviolet radiations of the Sun, which help in killing of mould spores present in air. Hence, it is advised that every living room in the house should get direct sunlight at least for a short time.

(b) No, tinned and sealed food are not always safe to eat as it may contain harmful bacteria like Clostridium botulinum that causes food poisoning. Clostridium botulinum releases toxins under low-oxygen conditions. These toxins are very lethal and can block nerve functions leading to muscular and respiratory paralysis.
Moreover, the chemicals used in the inner coating of the container can be harmful for humans.

Question 8.

State the differences between

(a) Decay and Putrefaction

(b) Pasteurization and Sterilization


(a) differences between Decay and Putrefaction
Decay Putrefaction
1. It is the complete breakdown of organic matter by bacteria. 1. It is the incomplete breakdown of organic matter by bacteria.
2. Does not emit a foul smell 2. Emits a foul smell
(b) differences between Pasteurization and Sterilization
Pasteurization Sterilization
1. Temperature- 60C 1. Temperature- 110C
2. Does not kill spores 2. Kills even spores
3. Partial sterilization 3. Complete sterilization
E.g. Pasteurization of milk E.g. Sterilization of canned food

Question 9.

Would there be any bacteria in an aquarium?


Yes, there would be bacteria in an aquarium

—  : End of Economic Importance of Bacteria Part (A) C. Short Answer Class-9 ICSE Biology Solutions :–

Return to  Return to Concise Selina ICSE Biology Class-9 


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