Economic Importance of Bacteria and Fungi ICSE Class-9 Selina Publishers Concise Biology Solutions Chapter-9 . We Provide Solutions of Progress Check , MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type Questions and Structured / Applications / Skill Type Questions of Exercise-9 Economic Importance of Bacteria and Fungi . Visit official Website CISCE  for detail information about ICSE Board Class-9.
Economic Importance of Bacteria and Fungi ICSE Class-9
(Selina Publishers Concise Biology Solutions Chapter-9 )
–: Select Topics :–
Section-(A) Bacteria
E. Structured /Application/Skill Type
Section-(B) Fungi
E. Structured /Application/Skill Type
Note :- Before Viewing Concise Solutions of Economic Importance of Bacteria and Fungi Chapter-9. Read the whole chapter carefully with figure. Focus on useful and harmful bacteria, Vaccine, antibiotics. importance of Yeast.Focus on useful and harmful role of fungi.
Progress Check (page-85),Exe-9(A) Economic Importance of Bacteria and Fungi Concise Biology Solutions
Question 1
Name ……….bacteria
Answer 1
Cocci (Spherical)
Bacilli (rod shape)
Spirilla (Spiral Bacteria)
Vibrio (Comma shape)
Note : 4 name is given write any three name only
 A. MULTIPLE CHOICE TYPE, Exe-9(A) Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
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
Answer 1
(d) they have no chlorophyll
Question 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)Â Escherichia
(b)Â Streptomyces
(c)Â Rhizobium
(d)Â Nitrobacter
Answer 2
(b)Streptomyces
Question 3
Which bacteria is rod shaped?
(a) Coccus
(b) Spirillum
(c) Bacillus
(d) Vibrio
Answer 3
(c) Bacillus
Question 4
Which bacteria fixes nitrogen in the soil?
(a)Â Nitrobacter
(b)Â Nitrosomonas
(c)Â Rhizobium
(d)Â Clostridium
Answer 4
(c)Rhizobium
B. VERY SHORT ANSWER TYPE ,Exe-9 (A) Economic Importance of Bacteria and Fungi Concise Biology Solutions
Question 1
Name the three common types of bacteria.
Answer 1
The three common types of bacteria are:
- Cocci (spherical bacteria)
- Bacilli (rod-shaped bacteria)
- Spirilla (spiral bacteria)
Question 2
Match the items in Column A with those in Column B.
| Column A | Column B |
| (i)Â Penicillium | (a) Bacteria occuring in chains |
| (ii) Diplococci | (b) Antibiotic |
| (iii) Streptococci | (c) Bacteria occurring in pairs |
Answer 2
| Column A | Column B |
| (i)Â Penicillium | (b) Antibiotic |
| (ii)Diplococci | (c) Bacteria occurring in pairs |
| (iii)Streptococci | (a) Bacteria occuring in chains |
C.SHORT ANSWER TYPE Exe-9(A)Â Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Would you consider the bacteria and yeast as plants? Give reason.
Answer 1
No, bacteria and yeast are not considered as plants because they do not have chlorophyll and their mode of nutrition is not autotrophic, which are characteristic features of plants.
Question 2
In what form bacteria may be present in the air?
Answer 2
Bacteria may be present in the form of spores in the air.
Question 3
Why is spore formation in bacteria not considered as a form of reproduction?
Answer 3
Spore formation in bacteria is not considered as a form of reproduction because bacteria reproduce only asexually by means of fission or cell division. Spore formation is just a method of escaping unfavourable conditions.
Question 4
In what respect do you consider bacteria as simple organisms?
Answer 4
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 5
State the differences between
(a) Decay and Putrefaction
(b) Pasteurization and Sterilization
Answer 5
Â
(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 |
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Question 6
Why is it generally advised that every living room in the house should get direct sunlight at least for a short time?
Answer 6
Direct sunlight contains ultraviolet radiations of the sun, which help in killing of mould spores present in air.
Question 7
Would there be any bacteria in an aquarium?
Answer 7
Yes, there would be bacteria in an aquarium
D. LONG ANSWER TYPE Exe-9(A)Â Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Both bacteria and yeast reproduce by asexual method, but how does this method differ in them?
Answer 1
Bacteria reproduce asexually by means of fission (binary fission), while yeast reproduces asexually by budding producing chains.
Question 2
Describe the role of micro-organisms in industrial production.
Answer 2
Role of micro-organisms in industrial production:
(1)Â Bacteria are used in the production of vinegar and in the processing of coffee, tobacco, etc.
(2) Different flavours of tea, coffee, etc. are produced by certain bacteria.
(3) Tanning of leather is basically brought about by sunlight, but there are a few micro-organisms which are involved in this process.
(4) Fibres used for making rope, linen, etc. are obtained by loosening the fibres of hemp and flax by retting, which involves the use of bacteria.
(5) Bacteria are used for the large-scale production of antibiotics, enzymes, hormones, serum, vaccines and toxoids.
Question 3
How do bacteria obtain their nourishment?
Answer 3
Modes of nutrition in bacteria:
- Autotrophic bacteria: Able to synthesize their own food
- Photoautotrophs: Contain chlorophyll and use light energy for the synthesis of food
- Chemoautotrophs: Obtain energy by oxidizing inorganic compounds
- Heterotrophic bacteria: Require organic compounds as their main source
- Saprophytes: Grow on dead and decaying organic matter
- Parasites: Obtain their food from living host on which they grow
Question 4
Describe any two uses of bacteria in industry.
Answer 4
Uses of bacteria in industry:
- Tea curing:Certain bacteria are used to produce different flavours of tea.
- Tanning of leather:Tanning of leather is basically brought about by sunlight, but there are a few bacteria which are involved in this process.
Question 5
What are antibiotics? Name any two examples.
Answer 5
Antibiotics are chemical substances produced by a living organism that kill or stop the growth of disease-causing micro-organisms such as fungi and bacteria.
Examples of antibiotics:
- Penicillin
- Streptomycin
Question 6
Is tinned and sealed food always safe to eat? Give reasons in support of your answer.
Answer 6
No, tinned and sealed food are not always safe to eat as they may contain harmful bacteria like Clostridium botulinum, which may cause serious food poisoning resulting in Botulism. In extreme cases, this condition may even prove to be fatal for life.
E. STRUCTURED/APPLICATION/SKILL TYPE Exe-9(A)Â Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Study the diagram given below and then answer the questions that follow:
……………
(a) Briefly describe how nitrogen of the atmosphere is converted to nitrates by leguminous plants.
(b) Name the bacterium that converts
(i) ammonium compounds to nitrites
(ii) nitrites to nitrates
(c) State how the nitrates in the soil get converted to nitrogen of the atmosphere.
(d) Role of plants and animals in the formation of ammonium compounds.
Answer 1
(a) Soil bacteria such as Rhizobium are present in the root nodules of leguminous plants. These bacteria convert free nitrogen of the soil atmosphere to soluble nitrates.
(b)
(i) Nitrosomonas converts ammonium compounds to nitrites.
(ii) Nitrobacter converts nitrites to nitrates.
(c) Denitrifying bacteria in the soil break down nitrates present in the soil to release nitrogen gas which enters the atmosphere.
(d) Nitrifying bacteria present in the soil convert nitrogenous wastes of animals and dead remains of plants and animals to ammonia. Ammonia is then converted to ammonium compounds. In this way, plants and animals help in the formation of ammonium compounds
EXERCISE 9-(B) Fungi
Progress Check (page-94),Exe-9(B) Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
which……mushroom
Answer 1
Agaricus
Question 2
What …….seed
Answer 2
cultivation of mushroom mycelium introduce in compost and allow to grow is called mushroom seed
Question 3
What………casting
Answer 3
A thin layer of soil is sprayed over compost
A. MULTIPLE CHOICE TYPE, Exe-9(B) Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Production of ethanol (C2H5OH) occurs in one of the life processes of:
(a) Bread mould
(b) Yeast
(c) Mushroom
(d) Penicillium
Answer 1
(b) Yeast
Question 2
Which one of the following characteristics is found in all fungi but not in all bacteria?
(a) Aerobic respiration
(b) Cell wall
(c) Spore formation
(d) A long circular DNA lying loose in the cytoplasm
Answer 2
(c) Spore formation
Question 3
Bacteria are referred to as prokaryotes because
(a) They have no chlorophyll.
(b) They are unicellular.
(c) They are free living.
(d) They do not have a true nucleus.
Answer 3
(d) They do not have a true nucleus
Question 4
Yeast is used in the production of
(a) Ethyl alcohol
(b) Acetic acid
(c) Cheese
(d) Curd
Answer 4
(a) Ethyl alcohol
B. VERY SHORT ANSWER TYPE Exe-9(B)Â Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Tick mark the correct statement/statements.
(a) All mushrooms are poisonous.
(b) All toadstools are poisonous.
(c) Some toadstools are poisonous.
(d) Some mushrooms are edible.
Answer 1
(a) All mushrooms are poisonous.
(b) All toadstools are poisonous.
(c) Some toadstools are poisonous.
(d) Some mushrooms are edible.
C. SHORT ANSWER TYPE Exe-9(B)Â Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
Where can you the mould Rhizopus most easily found?
Answer 1
Rhizopus is the common bread mould. It grows not only on bread, but also on a variety of organic matter such as paper, wood, cloth, animal dung, leather goods and food materials such as fruit, bread, pickles, chapati, etc. particularly in warm and humid climate.
Question 2
Why is it generally advised that every living room in the house should get direct sunlight at least for a short time?
Answer 2
Direct sunlight contains ultraviolet radiations of the sun which help in killing of mould spores present in air.
Question 3
Describe the role of certain fungi in industrial production.
Answer 3
Role of certain fungi in industrial production:
(1) Preparation of fermented foods and bakery products
(2)Â Preparation of alcoholic beverages
(3) Preparation of organic acids
(4) Production of enzymes
(5) Production of antibiotics
(6)Â Production of alcohol
(7) Production of wine
(8)Â Bread-making
(9)Â Cheese making
(10) Mushroom cultivation
Question 4
Mention two useful and harmful effects of wine.
Answer 4
Useful effects of wine:
- In mild quantities, wine acts as a stimulant.
- It can be used to stimulate hunger, reduce anxiety and improve digestion.
Harmful effects of wine:
- In large quantities, wine can trigger asthma attack and increase blood pressure.
- It can cause body ailments, particularly liver cirrhosis.
Question 5
Differentiate between:
(a) Saprophyte and parasite
(b) Aerobic and anaerobic respiration with regard to products
(c) Decay and putrefaction
Answer 5
(a) Differentiate between: Saprophyte and parasite
| Saprophyte | Parasite |
| Obtains nourishment from dead and decaying organic matter | Obtains nourishment from the body of the living host |
(b) Differentiate between:Aerobic and anaerobic respiration with regard to products
| Aerobic respiration |
Anaerobic respiration |
| Products – Carbon dioxide (CO2), water (H2O) and energy (ATP) | Products – Ethanol (2C2H5OH), carbon dioxide (CO2) and energy (ATP) |
(c) Differentiate between:Decay and putrefaction
| Decay | Putrefaction |
| Complete breakdown of organic matter by bacteria without the emission of foul smell | Incomplete breakdown of organic matter by bacteria along with the emission of foul smell |
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D. LONG ANSWER TYPE Exe-9(B) Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
What are antibiotics? Name any two examples.
Answer 1
Antibiotics are chemical substances produced by a living organism that kill or stop the growth of disease-causing micro-organisms such as fungi and bacteria.
Examples of antibiotics:
- Penicillin
- Streptomycin
Question 2
Is tinned and sealed food always safe to eat? Give reasons in support of your answer.
Answer 2
No, tinned and sealed food are not always safe to eat as they may contain harmful bacteria like Clostridium botulinum, which may cause serious food poisoning resulting in Botulism. In extreme cases, this condition may even prove to be fatal for life.
Question 3
Would there be any bacteria in an aquarium?
Answer 3
Bacteria can be present in an aquarium.
Bacteria are present everywhere; in air, soil, water and foodstuffs. They are found in boiling water and also below 0C. and They are present on the bodies of all living and non-living organisms. also They live on readymade food. In short, they are omnipresent.
Bacteria are heterotrophic and may be decomposers or micro-aerobic in nature. Their mode of reproduction is very fast.
E. STRUCTURED/APPLICATION/ SKILL TYPE, Exe-9(B)Economic Importance of Bacteria and Fungi Concise Biology SolutionsÂ
Question 1
If you leave a piece of moist bread covered under a small bell jar at a warm place, mould grows on it in a few days. Answer the following with reference to this observation:
(a) How did the mould get inside the bell-jar?
(b) What would happen if the bread was not covered by the bell-jar?
(c) What would happen if moist bread was placed in a refrigerator?
(d) What happens first on the bread-the mycelia or the spores?
(e) How does bread mould obtain nourishment? What type of nourishment is it- epiphytic, autotrophic, parasitic symbiotic, or saprophytic?
Answer 1
(a) Moulds are commonly present in air, water, etc. Hence, they were already present when moist bread was kept covered with the bell-jar.
(b) If bread was not covered with the bell-jar, moulds would have still appeared, but after some time. The warm and humid conditions inside the bell-jar promote rapid production of mould.
(c) Moulds do not grow below freezing point inside a refrigerator.
(d) Mycelia appear first on the bread.
(e) Bread mould obtains its nourishment through extracellular digestion from the substratum on which it grows. This mode of nourishment is called saprophytic nutrition.
Question 2
Write in proper sequence the five major steps in cultivation of the common edible mushrooms.
Answer 2
Major steps in the cultivation of common edible mushrooms:
(1) Composting:
 Composting involves mixing of various components such as wheat or paddy straw, chicken manure and organic and inorganic fertilizers in a fixed proportion. The temperature of compost is maintained at around 50C. The compost is kept undisturbed for about one week.
(2) Spawning:
 ‘Mushroom seed’ in the form of mycelium of mushroom to be grown is introduced into the heap of compost and left for spreading for around two days.
(3) Casing:
Casing is the most important step of mushroom cultivation. It involves spreading of a thin layer of soil over the compost. This provides humidity and support to the mushroom. It also serves to prevent the desiccation of the compost heap and helps in temperature regulation at around 20C-25C to forbid the growth of pests and diseases. The provision for circulating air around the compost bed should also be made.
(4) Cropping and harvesting:
Three major growth stages are observed, before mushrooms attain a fully grown form. Firstly, the mycelium, i.e. a network of fibrous mass, spreads out in 2 to 6 weeks, followed by the tiny pin head stage and finally the button stage, which is marked by an increase in the mushroom size, until it acquires marketable size.
(5) Preservation:Â
Mushrooms have a very short shelf-life. Processes such as vacuum cooling, bombardment by gamma radiation, followed by storage at 15C, freeze drying in a solution of citric acid, ascorbic acid and brine, etc. are used for the preservation of mushrooms.
Question 3
Comment on the following:
(a) Denitrifying bacteria are a blessing as well as a curse to farmers.
(b) Yeast is used in bakeries and breweries.
Answer 3
(a) Denitrifying bacteria
Denitrifying bacteria are a boon to farmers because they curb the excess supply of nitrates to plants. Excessive nitrates can even harm the ecosystem as a whole because some wild plants like cultivated crops can thrive on nitrogen.
Growth of these plants is favoured in nitrogen-saturated environments which can upset the ecosystem. Denitrifying bacteria are a curse to farmers because they breakdown soil nitrates to release free nitrogen gas into the atmosphere, thereby reducing the levels of nitrogenous compounds in the soil.
(b) Yeast is used in bakeries and breweries.
Yeast respires anaerobically in the absence of oxygen. It breaks down carbohydrates into simpler products such as ethanol by fermentation. The quality of alcohol produced varies with the kind of yeast employed.
During the baking process, yeast added to the dough ferments sugar and produces carbon dioxide. This causes the dough to rise, and when baked, the gas bubbles expand, giving the bread a light and spongy texture. Therefore, yeast is used in bakeries and breweries.