Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

Selina ICSE Solutions

Q) Multiple choice question:-

1) Bacteria are no more classified as plants primarily because:
a) these are unicellular
b) these are microscopic
c) many of them are parasitic
d) they have no chlorophyll
Solution: (d) they have no chlorophyll

2) A particular species of which one of the following, is the source bacterium of the antibiotic, discovered next to penicillin, for the treatment of tuberculosis?
a) Escherichia
b) Streptomyces
c) Rhizobium
d) Nitrobacter
Solution: (b) Streptomyces

3) Which bacteria are rods shaped?
a) Spirillum
b) Bacillus
c) Vibrio
Solution: (b) Bacillus

4) Which bacteria fixes nitrogen in the soil?
a) Nitrobacter
b) Nitrosomonas
c) Rhizobium
d) Clostridium
Solution: Rhizobium

Q) Very Short Answer:-

Question 1) Name the three common types of bacteria.

The three common types of bacteria are:
1. Cocci (spherical bacteria)
2. Bacilli (rod-shaped bacteria)
3. Spirilla (spiral bacteria)

Question 2) Match the items in Column A with those in Column B.

Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi


Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

Q) Short Answer Type:-

Question 1) Would you consider the bacteria and yeast as plants? Give reason.

No, would not consider. Bacteria and yeast cannot be considered as plants as bacteria belong to the Kingdom Monera while yeast belong to Kingdom Fungi. The category under which plants fall is Kingdom Plantae. They are eukaryotic, autotropic and multicellular entities. Both yeast and bacteria are unicellular. Bacteria are prokaryotes, that is to say, that the membrane-bound nucleus is absent. Consequently, yeast and bacteria cannot be categorized as plants as they do not have the characteristics that are commonly found in plants.

Question 2) In what form bacteria may be present in the air?

The air may include bacteria in the form of spores.

Question 3) Why is spore formation in bacteria not considered as a form of reproduction?

Since bacteria can only reproduce asexually by fission or cell division, spore formation in bacteria is not regarded as a type of reproduction. Just one way to get away from bad circumstances is to generate spores.

Question 4) In what respect do you consider bacteria as simple organisms?

Because bacteria are unicellular creatures without membrane-bound cell organelles like chloroplasts, mitochondria, etc., as well as without a clearly defined nucleus, they have a simpler cellular structure.

Question 5) State the differences between decay and putrefaction.

Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

Question 6) State the differences between pasteurization and sterilization.

Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

Question 7) Why is it generally advised that every living room in the house should get direct sunlight at least for a short time?

The UV radiation of the sun found in direct sunlight aids in the destruction of airborne mold spores.

Question 8) Would there be any bacteria in an aquarium?

An aquarium may contain bacteria. Bacteria can be found in the soil, water, food, and air. They may be found underneath CO2 and in boiling water. All living and non-living things have them on their bodies. They exist only in prepared meals. They are, in a word, everywhere. Bacteria are heterotrophic and can be microaerophilic or decomposers. They reproduce fairly quickly using this method.

Q) Long answer type:-

Question 1) Both bacteria and yeast reproduce by asexual method, but how does this method differ in them?

While yeast reproduces asexually by budding generating chains, bacteria reproduce asexually by fission (binary fission).

Question 2) Describe the role of micro-organisms in industrial production.

Microorganisms’ role in industrial production:
(1) Bacteria are employed to make vinegar and to process other products like coffee and tobacco.
(2) Specific microorganisms generate various tea, coffee, etc. flavors.
(3) Although a few microorganisms are involved, sunlight is mostly responsible for the tanning of leather.
(4) Hemp and flax fibers are loosened by retting, which uses bacteria, to produce fibers needed to make rope, linen, etc.
(5) Large-scale manufacture of antibiotics, enzymes, hormones, serum, vaccines, and toxoids all need bacteria.

Question 3) How do bacteria obtain their nourishment?

Bacterial nutrition modes:
1. Bacteria that can produce their own nourishment, or autotrophs.
2. Photoautotrophs: These organisms produce food using light energy and include chlorophyll.
Chemoautotrophs: These organisms produce energy by oxidizing inorganic substances.
4. Heterotrophic bacteria: These organisms rely mostly on organic substances as food.
5. Saprophytes: Grow on organic stuff that has died and is rotting.
6. Parasites feed on the live host on which they develop.

Question 4) What are antibiotics? Give ‘two’ examples.

To destroy or stop the growth of other germs, an antibiotic is a medication made from living things or bacteria. Bacteriostatic and bactericidal antibiotics are the two categories under which they are categorized (inhibits growth of bacteria).

Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

Question 6) Is tinned and sealed food always safe to eat? Give reasons in support of your answer.

No, canned and sealed food isn’t always safe to consume since they could contain dangerous germs like Clostridium botulinum, which can lead to botulism and other serious food poisoning. In some instances, this illness could potentially be life-threatening.

Q) Structure Skill Type Question:-

Question 1) Study the diagram given below and then answer the questions that follow:

Selina ICSE Class 9 Biology Solutions Chapter 9 Economic Importance Of Bacteria And Fungi

(i) Briefly describe how nitrogen of the atmosphere is converted to nitrates by leguminous plants.
(ii) Name the bacterium that converts
(a) ammonium compounds to nitrites
(b) nitrites to nitrates
(iii) State how the nitrates in the soil get converted to nitrogen of the atmosphere.
(iv) Role of plants and animals in the formation of ammonium compounds.

(i) Leguminous plants’ root nodules include soil microbes like Rhizobium. These microorganisms convert soluble nitrates from free nitrogen in the soil atmosphere.
(ii) (a) Nitrosomonas produces nitrites from ammonium molecules.
(b) Nitrites are changed into nitrates by Nitrobacter.
(iii) Nitrates in the soil are broken down by denitrifying bacteria, releasing nitrogen gas into the atmosphere.
(iv) Nitrifying bacteria in the soil turn animal wastes containing nitrogen and the remnants of dead plants and animals into ammonia. The result is compounds made of ammonium from ammonia. Animals and plants contribute to the synthesis of ammonium compounds in this way.

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