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Chapters
1: Reproduction in Organisms
2: Sexual Reproduction in Flowering Plants
3: Human Reproduction
4: Reproductive Health-Problems and Strategies
Unit 2 – Genetics and Evolution
5: Principles of Inheritance and Variation
6: Chromosomes, Sex-Linked Inheritance and Human Genetic Disorders
7: Molecular Basis of Inheritance
8: Evolution-Origin of Life
9: Theory of Evolution and Evolution of Man
Unit 3 – Biology and Human Welfare
10: Human Health and Diseases
11: Adolescent Issues: Alcoholism and Drugs
12: Animal Breeding for Improvement in Food Production
13: Plant Breeding to Enhance Food Production
▶ 14: Microbes in Human Welfare
Unit 4 – Biotechnology
15: Biotechnology: Principles and Processes
16: Biotechnology and Its Applications
Unit 5 – Ecology and Environment
Chapter 17: Organisms and Populations
Chapter 18: Ecosystem
Chapter 19: Biodiversity and Conservation
Chapter 20: Environmental Issues
![Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 14 - Microbes in Human Welfare - Shaalaa.com](/images/biology-english-class-12-isc_6:65d11b7ee3eb4277bbdac77874c6c42a.jpg "Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 14 - Microbes in Human Welfare")
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Solutions for Chapter 14: Microbes in Human Welfare
Below listed, you can find solutions for Chapter 14 of CISCE Sarita Aggarwal for Biology [English] Class 12 ISC.
Sarita Aggarwal solutions for Biology [English] Class 12 ISC 14 Microbes in Human Welfare EXERCISES [Pages 754 - 765]
A. OBJECTIVE QUESTIONS I. Multiple choice questions Choose the correct answer:
The bacteria used for converting milk into curd is ______.
Bacillus lacto
Lactobacillus
Lactogen
Streptococcus
Scientific name of Baker's yeast is ______.
Saccharomyces cerevisiae
Staphylococcus
Aspergillus niger
Streptococcus thermophilus
The specific distinct flavour of 'Roquefort cheese' is due to ripening by a specific ______.
bacteria
fungi
algae
virus
The source of sugar for making beer is ______.
grape juice
fruit juice
barley grains
none of these
The antibiotic penicillin is produced from ______.
bacteria
fungi
lichen
algae
Which of the following is not a useful product of microbes?
pectinase
cyclosporin A
statin
ptyalin
In the aeration tanks the sewage is treated/mixed with ______.
anaerobic bacteria
sedimenters
biogas
aerobic bacteria
Biogas is mainly ______.
O2
CO2
N2
CH4
Which of the following bacteria is found in symbiotic association with legumes?
Azotobacter
Rhizobium
Azospirillum
Bacillus
Which of the following bacteria is found in association with roots of grasses and rice?
Azotobacter
Rhizobium
Azospirillum
Anabaena
Biofertilisers give a better yield when added along with ______.
phosphate fertilisers
calcium fertiliser
nitrogen fertilisers
urea
The cyanobacterium, Anabaena azollae, lives in association with ______.
roots of leguminous plants
leaves of a floating fern
roots of pine trees
bacteria and fungi
Ectomycorrhiza is an association of ______.
bacteria and plant roots
cyanobacteria and plant roots
fungi and plant roots
bacteria and fungi
Cultivation of Bt cotton has been much in the news. The prefix Bt means ______.
barium-treated cotton seeds
bigger thread variety of cotton
produced by biotechnology
carrying an endotoxin gene from Bacillus thuringiensis
Mycorrhiza promotes plant growth by
Serving as a plant growth regulators
Absorbing inorganic ions from soil
Helping the plant in utilizing atmospheric nitrogen
Protecting the plant from infection
Which one is a neem product that is used as an insect repellent?
azadirachtin
rotenone
parathione
endrin
The gene ‘cry' is naturally present in ______.
Bacillus thuringiensis
Brassica
tissue culture
Spirulina
Which of the following is used as an immunosuppressive agent in organ transplants?
Statins
Cyclosporin A
Penicillin
Gluconic acid
The following molecules are used as blood-cholesterol lowering agents.
Cyclosporin A
Streptokinase
Aspergillus
Statins
Methanogens are found in the following.
vehicle fuel
bio gas
colon of humans
rumen of cattle
Fill in the blanks
Milk is converted into curd by ______ bacteria.
In cheese making, the milk is fermented by the 'starter culture' of usually ______ bacteria.
Fermentation of alcoholic beverages is done by ______, also called Brewer's yeast.
Chemical substances produced by certain microbes that kill or inhibit the growth of other disease-causing microbes are called ______.
______ enzyme, produced by bacteria and modified by genetic engineering, is used as a 'clot buster'.
Cyclosporin A biomolecule is produced by fungi ______.
______ is the main source of methanogens for the production of biogas.
______ bacteria is used as a biopesticide to produce Bt cotton.
The cyanobacteria ______ is a biofertiliser found in association with the leaves of floating fern.
BOD of ______ water is more than the drinking water.
State whether the following is true or false.
Viroids and prions are pathogens that are simpler than viruses.
State whether the following is true or false.
Baking of bread is done by adding yeast called Streptococcus thermophilus.
State whether the following is true or false.
Antibiotic penicillin is derived from a bacteria called Penicillim.
State whether the following is true or false.
Primary treatment of sewage is a physical process while secondary treatment is done by adding bacteria.
State whether the following is true or false.
Main component of biogas is methane and is produced by microbial fermentation.
Match the following.
| Column A | Column B |
|---|---|
| 1. Lactobacillus | (a) Proteases |
| 2. Streptococcus thermophilus | (b) Cheese making |
| 3. Aspergillus | (c) Antibiotic |
| 4. Penicillium | (d) Lipases |
| 5. Candida lipolytic | (e) Curd |
| 6. Naturally occurring pesticide | (f) Azadirachtin |
| 7. Pesticide of fungal origin | (g) Phytophthora palmivora |
| 8. Azolla | (h) Azospirillum |
| 9. Maize | (i) Mycorrhizae |
| 10. Pea | (j) Anabaena |
Answer the following in one or two words.
Bacteria that causes curdling of milk.
Answer the following in one or two words.
Bacteria used in ripening of Swiss cheese.
Answer the following in one or two words.
Microbe producing citric acid.
Answer the following in one or two words.
Microbe used for commercial production of ethanol.
Answer the following in one or two words.
Molecule used as immunosuppressive agent.
Answer the following in one or two words.
Term given to useful aerobic bacterial growth in secondary treatment of sewage.
Answer the following in one or two words.
Major component of biogas.
Answer the following in one or two words.
Major source of methanogens in production of biogas.
Answer the following in one or two words.
Many members of this genus form mycorrhizae.
Answer the following in one or two words.
Free-living nitrogen-fixing bacteria.
In the questions given below, there are two statements marked as Assertion (A) and Reason (R). Read the statements and choose the correct option
Assertion (A): Lactobacillus bacteria are added to milk to convert it into curd.
Reason (R): Lactobacillus bacteria add to the nutritive value by increasing vitamin B12 content.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Yeast such as Saccharomyces cerevisiae is used in baking industry.
Reason (R): Carbon dioxide produced during fermentation causes bread dough to rise by thermal expansion.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): The primary treatment of sewage is called the physical treatment while the secondary treatment is called the biological treatment.
Reason (R): Primary sewage treatment depends only upon sedimentation properties of materials present in sewage and filtration.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Baculoviruses are pathogens that attack insects and other arthropods and they are being used as biological control agents.
Reason (R): These viruses are speciesspecific and so have a narrow spectrum and destroy specific pests or insects.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Leguminous plants are nitrogen fixers.
Reason (R): Leguminous plants have Rhizobium in their root nodules.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Mycorrhizae are symbiotic associations between fungi and cyanobacteria.
Reason (R): Cyanobacteria are photosynthetic nitrogen fixers and so increase the efficiency of fungi.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Disadvantages of synthetic pesticides can be overcome by the use of natural biopesticides.
Reason (R): Biopesticides are harmless agents which are used to control weeds and pest without causing any damage.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Dragon flies can be used to decrease occurrence of diseases like malaria, dengue, etc.
Reason (R): Baculoviruses are effective in controlling many insects and other arthropods.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): Acetic acid production involves both aerobic and anaerobic processes.
Reason (R): Production of alcohol from glucose is an aerobic process and production of acetic acid from alcohol is an anaerobic process.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Assertion (A): An organ transplant patient, if not provided with cyclosporin A, may reject the transplanted organ.
Reason (R): Cyclosporin A inhibits activation of T-cells and interferes with destruction of non-self cells.
Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.
Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.
Assertion (A) is true but reason (R) is false.
Both assertion (A) and reason (R) are false.
Read the sources given and answer any four from the questions given below:
|
An antibiotic is a chemical substance which is produced by certain microbes (bacteria and fungi) and can kill or inhibit the growth of other disease-causing microbes. Most antibiotics treat bacterial infections but some can treat certain parasitic or fungal infections also. The antibiotic penicillin was discovered by Sir Alexander Fleming in 1928. It was extracted from a microscopic fungus Penicillium notatum. Fleming was studying the bacterium, Staphylococcus that causes throat infection in humans. He noticed that one culture of this bacteria was contaminated with a fungus. In that culture, the colonies of Staphylococcus immediately surrounded by the fungus had been destroyed but other colonies further away were normal. Penicillin has been used to treat tonsillitis, throat infections and different types of wound infections. Penicillin prevents the bacteria from synthesising peptidoglycan and blocks cross-linking of cell wall. After penicillin, many antibiotics have been extracted from various bacteria and fungi. One of the most productive sources of antibiotics has been the genus Streptomyces, a bacterium of which there are many species, from which over 500 antibiotics have been derived. Most commonly used antibiotics include streptomycin, tetracycline, erythromycin, etc. |
- The antibiotic penicillin was extracted from the following
- bacteria
- fungus
- cyanobacteria
- lichen
- Staphylococcus causes the following in humans
- wound infection
- skin infection
- throat infection
- stomach infection
- A large number of antibiotics have been derived from
- fungus Streptomyces
- bacteria Streptomyce
- Streptomycin
- Staphylococcus
- An antibiotic is a chemical substance that is produced by certain
- bacteria
- fungi
- both (a) and (b)
- protozoans
- How does antibiotic penicillin help to treat infections?
- It inhibits synthesis of bacterial cell wall
- It kills the bacteria
- It produces bactericidal chemicals
- It encircles bacteria and destroys them
Read the sources given and answer any four from the questions given below:
|
Enzymes are the biochemical molecules, capable of catalysing reactions. Over 300 enzymes are being used in industries and pharmaceuticals produced by a wide variety of microbes, mostly fungi. Amylases are obtained from fungiAspergillus, Rhizopus and some species of Bacillus (bacteria). They are capable of degrading starch and are used for the production of alcoholic beverages, in textile industries, confectioneries and paper industry. Lipases, the fatdigesting enzymes, are obtained from Penicillium, Rhizopus and Candida are used in detergent fermentations and for removing oily stains from the laundry. Proteases obtained from Aspergillus niger and Bacillus species degrade proteins and polypeptides. Pectinases are used to clear bottled fruit juices. Streptokinase, produced by bacteria, Streptococcus and modified by genetic engineering is used as a 'clots buster' for removing clots from the blood vessels of the patients. Some microbes help in the production of bioactive molecules like Cyclosporin A, produced by fungi, Trichoderma polysporum. It is used as an immunosuppressive agent in organ-transplant patients by inhibiting the activation of T cells. |
- Lipases are not obtained from
- Penicillium
- Aspergillus
- Rhizopus
- Candida
- The bottled fruit juices are cleared by the following enzymes
- Pectinases
- Streptokinase
- Proteases
- Hydrolases
- A person who underwent an organ transplant was given the following
- Aspergillus
- Candida
- Cyclosporin A
- Streptokinase
- Streptokinase, modified by genetic engineering, is used for the following
- organ transplant
- clearing bottled juices
- alcoholic fermentation
- removing clots from blood vessels
- The following enzymes are used in the production of alcohol beverages and confectionaries
- proteases
- amylases
- lipases
- lactase
Read the sources given and answer any four from the questions given below:
|
A biogas plant is where biogas is produced by fermenting the biomass. Biogas is a mixture of gases, mainly consisting of methane (50–70%) and carbon dioxide and has small amounts of nitrogen and hydrogen. It is produced from the raw materials such as agricultural waste, manure, municipal waste, plant waste, cow dung, sewage, green waste or food waste. It is a renewable source of energy with almost zero-emission. Biogas is produced by anaerobic fermentation of biomass by anaerobic bacteria or methanogens inside an anaerobic digester or bioreactor. The waste generated from a biogas plant can be converted into fertiliser and spread directly onto the fields. Biogas can be used as a fuel for any heating purpose, cooking and lighting. |
- Biogas is mainly a mixture of the following gases
- carbon dioxide and methane
- carbon dioxide and hydrogen
- methane and oxygen
- methane and nitrogen
- Biogas is formed by the following process
- aerobic fermentation by bacteria
- anaerobic fermentation by yeast
- anaerobic fermentation by bacteria
- aerobic fermentation by yeast
- Which of the following is not used as a raw material for biogas formation?
- agricultural waste
- cow dung
- food waste
- plastic waste
- The biomass used to form biogas is digested by the
- biofertilisers
- Rhizobium bacteria
- methanogens
- bio-enzymes
- The waste generated from the biogas can be used as
- feed for animals
- industrial fuel
- fuel for lighting
- fertilisers
B. SUBJECTIVE QUESTIONS Very short answer type questions (1 mark)
Name the microbes that turn milk into curd.
Name the microbes involved in the fermentation of idli batter.
What is the source of sugar in beer?
What is the source of sugar in wine?
Give sources of enzyme used to remove clots from blood vessels in heart attack.
What is Cyclosporin A?
What is the importancе of Cyclosporin A?
What is mycorrhiza?
What is the importance of soil bacteria, Bacillus thuringiensis in plants?
What is Bt cotton?
Give an example of biopesticide.
Name a bioherbicide.
Give two advantages of biopesticides.
Short answer type questions (2 marks)
How is milk converted into curd? Explain the process of curd formation.
Why do the cakes and bread rise while baking?
Why is penicillin called an antibiotic?
Can we call yeast an antibiotic? Explain in a line or two.
Name two antibiotics produced from bacteria.
What is the use of statins?
Name the microbe that produces statins.
List the important steps in primary treatment of sewage.
What is BOD?
How do anaerobic sludge digesters help?
What is the role of methanogens in biogas?
Name the bacteria present in stomach of cattle that digest cellulose and can help in production of biogas.
Name viruses used as biological control agents.
Why is fern Azolla frequently grown with the rice crop?
How do mycorrhizae help a plant?
Name a few natural insecticides.
What is the role of IPM?
What is Bt cotton?
In what way is Bt cotton different from normal cotton?
Short answer type questions (3 marks)
Name three microbes along with their scientific names that are used in household products.
Which antibiotic was very useful in World War II?
Why should antibiotics be used judiciously?
Give three examples of some common antibiotics.
Name three microbes used to produce enzymes along with their specific functions.
Name the microbes and their products used in removing clots in heart attack.
Name the microbes and their products used in organ transplants.
Name the microbes and their products used in lowering blood-cholesterol.
Give the basic steps involved in primary treatment of sewage water.
Give the basic steps involved in secondary treatment of sewage water.
Give the basic steps involved in tertiary treatment of sewage water.
What is the role of methanogens in biogas?
From where are methanogens obtained?
What is the composition of biogas?
What are the effects of chemical pesticides on crops?
Give two examples of chemical pesticides.
How biopesticides can be helpful?
Give three examples of microbes used as biofertilisers.
What are bioherbicides?
Give two examples of bioherbicides.
What is mycorrhiza?
What is the difference between ectomycorrhiza and endomycorrhiza?
Differentiate between the following:
Primary and Secondary treatment of sewage in 'wastewater plants'
Differentiate between the following:
Bt cotton and Normal cotton
Differentiate between the following:
Symbiotic and Non-symbiotic bacteria as fertilisers
What is the difference between ectomycorrhiza and endomycorrhiza?
Long answer type questions (5 marks)
Explain the process of fermentation of alcoholic beverages like beer and wine.
How was antibiotic penicillin discovered?
What is the significance of antibiotic penicillin?
What is the role of microbes in production of enzymes?
What is the role of microbes in production bioactive molecules?
Give three examples of enzymes.
Give three examples of bioactive molecules.
Explain the role of microbes in fermentation industry.
How are microbes helpful in treating wastewater sewage?
How is biogas produced?
List various reasons that led to the use of biofertilisers and biopesticides though chemical fertilisers or pesticides increased the yield of crops?
Justify the statement—"legumes fertilise the soil but not the cereals".
Explain a few biological methods to control the pest population.
Which organisms can act like biofertilisers? Explain with examples.
What are bio-pesticides?
Give any two examples of the application of biopesticides.
What is mycorrhiza?
How does mycorrhizae act as a biofertiliser?
E. BOARD QUESTIONS 1 mark
Which of the following is paired incorrectly:
Cyclosporin A - Trichoderma polysporum
Streptokinase - Saccharomyces cerevisiae
Swiss Cheese - Propionibacterium
Penicillin - Penicillium
Give the biological name of the following:
The mould from which penicillin is obtained.
Give the biological name of the following:
Baker’s yeast
Give the biological name of the following:
The microbe used to produce Swiss cheese.
Give the biological name of the following:
A symbiotic nitrogen-fixing bacterium found in root nodules.
3 marks
Study the table given below. Do not copy the table, but write the answers in the correct order.
| Scientific Name | Commercial Product | Use |
| (a) ____________ | Streptokinase | (b) ____________ |
| Monascus purpureus | (c) ____________ | (d) ____________ |
| (e) ____________ | Lactic acid | (f) ____________ |
Solutions for 14: Microbes in Human Welfare
Sarita Aggarwal solutions for Biology [English] Class 12 ISC chapter 14 - Microbes in Human Welfare
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