Mix Examples - Microbes in Human Welfare Questions in English

(D) Micro-organisms play a significant role in various fields:
$1$. Sewage disposal: Bacteria and fungi are used in treatment plants to decompose organic matter in sewage.
$2$. Biological control of diseases: Certain microbes like $Bacillus$ $\text{thuringiensis}$ are used as bio-pesticides to control pests and diseases without harming the environment.
$3$. Biological warfare: Historically and theoretically, certain pathogenic micro-organisms have been studied or used for biological warfare purposes.
Therefore, all the given options are correct.

(D) Bacteria perform several beneficial activities in the ecosystem:
$1$. Nitrogen fixation: Bacteria like $Azotobacter$ and $Clostridium$ fix atmospheric $N_2$ into ammonia.
$2$. Nitrification: Bacteria like $Nitrosomonas$ and $Nitrobacter$ convert ammonia into nitrites and nitrates.
$3$. Biogeochemical cycles: Bacteria act as decomposers,breaking down complex organic compounds into simple inorganic substances,which is essential for nutrient cycling.
Therefore,all the mentioned activities are useful functions performed by bacteria.

(C) Griseofulvin is an antibiotic derived from the fungus $Penicillium$ $griseofulvum$.
It exhibits antifungal properties and is specifically used to treat fungal infections of the skin, hair, and nails, such as ringworm.

(D) . $Spirulina$ is a well-known source of single-cell protein $(SCP)$.
$B$. $Rhizobium$ is a symbiotic bacterium that fixes atmospheric nitrogen and acts as a biofertilizer.
$C$. $Streptomyces$ is a genus of bacteria known for producing various antibiotics.
$D$. $Serratia$ is a genus of Gram-negative bacteria; it is not associated with drug addiction. Therefore,this pair is incorrectly matched.

(D) When fruit juices are left in an open place,they are exposed to various microorganisms present in the atmosphere,such as bacteria and yeast.
These microorganisms utilize the sugars present in the juice as a substrate for their metabolic activities.
Fermentation by yeast and the metabolic breakdown by bacteria lead to the production of various organic acids and other compounds,which alter the chemical composition and flavor profile of the juice,often resulting in a bitter or sour taste.

(C) $Rhizobium$ is a well-known nitrogen-fixing bacterium used as a biofertilizer.
$Streptomyces$ is a genus of bacteria known for producing various antibiotics.
$Spirulina$ is a cyanobacterium widely used as a source of single-cell protein $(SCP)$.
$Serratia$ is a genus of Gram-negative bacteria,often associated with hospital-acquired infections,and is not related to drug addiction. Therefore,this pair is incorrectly matched.

(A) The pair $A$ (Coliforms - Vinegar) is incorrect.
$1$. Coliforms are a group of bacteria (like $Escherichia coli$) used as indicators of water pollution, not for vinegar production.
$2$. Vinegar (acetic acid) is produced by the bacterium $Acetobacter aceti$.
$3$. Methanogens produce methane (biogas/gobar gas) in anaerobic conditions.
$4$. Yeast $(Saccharomyces cerevisiae)$ is used for the fermentation of sugars into ethanol.
$5$. Streptomycetes are a genus of Actinobacteria known for producing various antibiotics.

(D) $1$. $Aspergillus$ $niger$ (a fungus) is used for the commercial production of Citric acid.
$2$. Yeast ($Saccharomyces$ $cerevisiae$) is used for ethanol production,whereas Statins are produced by the yeast $Monascus$ $purpureus$.
$3$. $Acetobacter$ $aceti$ (a bacterium) is used for the production of Acetic acid.
$4$. $Clostridium$ $butylicum$ (a bacterium) is used for the production of Butyric acid,not Lactic acid. Lactic acid is produced by $Lactobacillus$.

(D) Antibiotics are chemical substances produced by some microbes and can kill or retard the growth of other (disease-causing) microbes.
Most of the antibiotics used in medicine today are derived from bacteria and actinomycetes.
Specifically,many antibiotics are produced by members of the genus $Streptomyces$,which belongs to the group actinomycetes.
Therefore,both bacteria and actinomycetes are major sources of antibiotics.

(B) The first pheromone to be chemically identified was $Bombykol$,which is secreted by the female silkworm $Bombyx mori$. This discovery was made by the German biochemist $Adolf Butenandt$ and his colleagues,including $Peter Karlson$,in $1959$. Since $Karlson$ is the only name listed among the researchers involved in this landmark study,$B$ is the correct answer.

(D) Silage is a type of fodder or cattle feed that is preserved by fermentation.
It is produced by the anaerobic fermentation of carbohydrates present in green plant tissues (such as grass,maize,or other cereals) by lactic acid bacteria.
Therefore,statements $(iii)$ and $(v)$ are correct.
Statement $(i)$ refers to the production of Swiss cheese.
Statement $(ii)$ refers to the use of $Saccharomyces$ $cerevisiae$ (Baker's yeast).
Statement $(iv)$ refers to the industrial production of ethanol using yeast.

(D) The correct matches are as follows:
$(a)$ $LAB$ (Lactic Acid Bacteria) increases the nutritional quality of milk by increasing Vitamin $B_{12}$ content. Thus, $(a-ii)$.
$(b)$ $Saccharomyces$ $cerevisiae$ (Brewer's yeast) is used in the baking industry for bread making. Thus, $(b-iii)$.
$(c)$ $Propionibacterium$ $sharmanii$ is used for the production of Swiss cheese, which is characterized by large holes due to the production of a large amount of $CO_2$. Thus, $(c-iv)$.
$(d)$ Silage is a type of fodder made from green foliage crops which have been preserved by fermentation, used as cattle feed. Thus, $(d-i)$.
Therefore, the correct sequence is $(a-ii), (b-iii), (c-iv), (d-i)$.

(C) The correct answer is $C$.
$1$. Yeast $(Saccharomyces \text{ } cerevisiae)$ is used for the production of ethanol through fermentation.
$2$. Streptomyces is a genus of bacteria used to produce various antibiotics.
$3$. Coliform bacteria (like $E. \text{ } coli$) are indicators of water pollution, whereas vinegar is produced by $Acetobacter \text{ } aceti$. Thus, this pair is mismatched.
$4$. Methanogens are bacteria that produce methane (biogas or gobar gas) in anaerobic conditions.

(B) The correct matches are as follows:
$1$. $Ashbya$ $gossypii$ $(I)$ produces Riboflavin $(f)$,which is a Vitamin $(t)$. Thus,$I-f-t$.
$2$. $Trichoderma$ $polysporum$ $(II)$ produces Cyclosporin-$A$ $(h)$,which is an Immunosuppressive agent $(s)$. Thus,$II-h-s$.
$3$. $Rhizopus$ $nigricans$ $(III)$ produces Hydroxy progesterone $(d)$,which is used in the production of Contraceptive pills $(q)$. Thus,$III-d-q$.
$4$. $Monascus$ $purpureus$ $(IV)$ produces Statins $(e)$,which act as a Cholesterol lowering agent $(p)$. Thus,$IV-e-p$.
Therefore,the correct sequence is $I-f-t, II-h-s, III-d-q, IV-e-p$.

(A) The correct matching is as follows:
$1.$ Saccharomyces cerevisiae is used in bread making $(1-B)$.
$2.$ Penicillium notatum is the source of the antibiotic Penicillin $(2-D)$.
$3.$ Ashbya gossypii is used for the industrial production of Riboflavin $(3-A)$.
$4.$ Rhizopus nigricans is used for the production of Hydroxy progesterone $(4-E)$.
$5.$ Trichoderma polysporum produces the immunosuppressive agent Cyclosporin-$A$ $(5-F)$.
$6.$ Monascus purpureus is used to produce statins (sterins) which act as blood-cholesterol lowering agents $(6-C)$.
Thus, the correct sequence is $1-B, 2-D, 3-A, 4-E, 5-F, 6-C$.

(D) The correct answer is $D$.
$A$ consists of organic acids.
$B$ consists of enzymes.
$C$ consists of antibiotics.
$D$ is the odd group because it contains a mixture of a vitamin $(Riboflavin)$, an enzyme $(Rennin)$, an organic acid $(Itaconic \text{ acid})$, and a hormone $(Progesterone)$, whereas the other groups contain items belonging to the same functional category.

(A) The correct matches are as follows:
$1.$ Production of methane is associated with methanogens, which act as an alternative source of energy $(c)$.
$2.$ Carbamycin is an antibiotic $(e)$.
$3.$ Streptokinase is used as a 'clot buster' for removing clots from the blood vessels of patients who have undergone myocardial infarction $(d)$.
$4.$ $L-Lysine$ is an amino acid $(b)$.
$5.$ Cyclosporin-$A$ is used as an immunosuppressive agent in organ transplant patients $(f)$.
$6.$ Hydroxy progesterone is a steroid $(a)$.
Therefore, the correct sequence is $1-c, 2-e, 3-d, 4-b, 5-f, 6-a$.

(C) The correct matches are as follows:
$1.$ $LAB$ (Lactic Acid Bacteria) is responsible for $c.$ Lactic acid production.
$2.$ $Propionibacterium$ $shermanii$ is used in the production of $d.$ Swiss cheese.
$3.$ $Acetobacter$ $aceti$ is used for the production of $f.$ Acetic acid.
$4.$ $Clostridium$ $butylicum$ is responsible for the production of $g.$ Butyric acid.
$5.$ $Pseudomonas$ (specifically $Pseudomonas$ $putida$) is used in bioremediation, often associated with products like $a.$ Quantum $-4000$ (a commercial product for oil spill cleanup).
$6.$ $Azospirillum$ is a $b.$ Free-living $N_2$-fixer.
Therefore, the correct sequence is $(1-c), (2-d), (3-f), (4-g), (5-a), (6-b)$.

(D) Antibiotics are chemical substances produced by some microbes that can kill or retard the growth of other disease-causing microbes. The discovery of antibiotics, such as penicillin, revolutionized the treatment of deadly bacterial diseases. Plague $(Yersinia pestis)$, Diphtheria $(Corynebacterium diphtheriae)$, and Whooping cough $(Bordetella pertussis)$ are all serious bacterial infections that were once considered fatal but became treatable with the advent of antibiotics. Therefore, all the listed diseases are examples of conditions for which antibiotics have been successfully used.

(D) The correct answer is $D$.
$Trichoderma$ $polysporum$ is a fungus,not a yeast.
It is used for the production of Cyclosporin $A$,which acts as an immunosuppressive agent in organ transplant patients.
Other options are correct:
- Microorganisms are widely used in industries to produce enzymes like lipases,proteases,and pectinases.
- Proteases and lipases are used in laundry detergents to remove oily stains.
- Microorganisms are used for the commercial production of vitamins (e.g.,Vitamin $B_{12}$).

(A) The correct matches are as follows:
$1$. $(a)$ Trichoderma polysporum produces Cyclosporin $A$, which acts as an immunosuppressive agent in organ transplants. Thus, $(a-s-iv)$.
$2$. $(b)$ Riboflavin is a type of Vitamin. Thus, $(b-q-ii)$.
$3$. $(c)$ Monascus purpureus produces Statins, which act as blood cholesterol-lowering agents. Thus, $(c-r-iii)$.
$4$. $(d)$ Streptococcus produces Streptokinase, which is used as a 'clot buster' to remove clots from the blood vessels of patients who have undergone myocardial infarction. Thus, $(d-p-i)$.
Therefore, the correct sequence is $(a-s-iv, b-q-ii, c-r-iii, d-p-i)$.

(C) $Assertion (S)$ is true: Alexander Fleming, Ernest Chain, and Howard Florey were awarded the Nobel Prize in $1945$ for the discovery and development of penicillin.
$Reason (R)$ is false: Lactic acid is produced by the bacterium $Lactobacillus$, not by the fungus $Aspergillus$ $niger$. $Aspergillus$ $niger$ is used for the production of citric acid.

(D) The correct answer is $D$.
$A$. $Acetobacter$ $aceti$ is a bacterium used for the commercial production of acetic acid.
$B$. $Propionibacterium$ $shermanii$ is used for the production of Swiss cheese,which is characterized by large holes due to the production of a large amount of $CO_2$.
$C$. $Trichoderma$ $polysporum$ is a fungus used to produce the bioactive molecule cyclosporin $A$,which is used as an immunosuppressive agent in organ transplant patients.
$D$. $Streptococcus$ is a bacterium used for clot busters (streptokinase),whereas $Monascus$ $purpureus$ is a yeast used for the production of statins (blood-cholesterol lowering agents). Therefore,the pair $Streptococcus - Monascus$ is incorrectly matched.

(A) $1.$ Silage is a type of fermented, high-moisture stored fodder which can be fed to cattle, hence $(1-b)$.
$2.$ Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures during sewage treatment, hence $(2-c)$.
$3.$ Biogas is produced by the anaerobic breakdown of organic waste by methanogens, hence $(3-d)$.
$4.$ $BOD$ (Biochemical Oxygen Demand) is a measure of the amount of oxygen required by aerobic microorganisms to decompose organic matter in water, serving as an indicator of water pollution, hence $(4-a)$.
Therefore, the correct matching is $(1-b), (2-c), (3-d), (4-a)$.

(C) Methanogens are a group of bacteria that produce methane $(CH_4)$ in anaerobic conditions, which is a major component of biogas used as an energy source. Brewer's yeast $(Saccharomyces \text{ } cerevisiae)$ is used in the production of ethanol, which is also a biofuel (energy source). Therefore, both are useful for obtaining energy sources.

(B) The correct matches are as follows:
$1$. Trichoderma is a free-living fungus that is very common in root ecosystems and acts as an effective biocontrol agent against several plant pathogens $(1-b)$.
$2$. Pseudomonas (specifically certain strains like Pseudomonas fluorescens) is used as a biocontrol agent,but in the context of specific commercial products mentioned in textbooks,Quantum-$4000$ is a product based on Pseudomonas $(2-a)$.
$3$. Baculoviruses are pathogens that attack insects and other arthropods. They are excellent candidates for species-specific,narrow-spectrum insecticidal applications $(3-d)$.
$4$. Bt Cotton is a genetically modified crop that expresses the Cry protein,which provides resistance against crop-sucking and boring pests $(4-c)$.
Therefore,the correct sequence is $(1-b), (2-a), (3-d), (4-c)$.

(A) The correct answer is $A$.
$Quantum$ $4000$ is a commercial formulation of the bacterium $Bacillus$ $thuringiensis$ $(Bt)$,which is used as a bioinsecticide to control specific insect larvae,not fungi.
$B.T.$ gene is correctly associated with pest control.
Bionematicides are used to control nematodes.
Baculoviruses are pathogens that attack insects and other arthropods,making them effective biological control agents.

(D) To avoid environmental pollution,the use of eco-friendly alternatives to chemical fertilizers and pesticides is essential.
$1$. Biofertilizers (like Rhizobium,Azospirillum) enrich the soil nutrients naturally without chemical runoff.
$2$. Biopesticides (like Bacillus thuringiensis) control pests without leaving toxic residues in the environment.
$3$. Single Cell Protein $(SCP)$ production from waste materials helps in waste management and provides a sustainable protein source.
Therefore,all these options contribute to reducing environmental pollution.

(C) The correct answer is $C$.
$1$. Yeast $(Saccharomyces \text{ } cerevisiae)$ is used in the production of ethanol through fermentation.
$2$. Streptomyces is a genus of bacteria known for producing various antibiotics.
$3$. Cyanobacteria are primarily used as bio-fertilizers (e.g., Anabaena, Nostoc) to fix atmospheric nitrogen, not as bio-insecticides. Bacillus thuringiensis is a well-known example of a bio-insecticide.
$4$. Methanogens are anaerobic bacteria that produce methane (biogas) from organic waste.

(D) Statement $S$ is false because cellulase is an enzyme that breaks down cellulose,not oily stains. Lipases are used in laundry detergents to remove oily stains.
Statement $R$ is false because Cyclosporin-$A$ is an immunosuppressive agent used in organ transplant patients to prevent rejection. Streptokinase is the enzyme used as a 'clot buster' to remove clots from blood vessels.
Therefore,both statements $S$ and $R$ are false.

(D) The correct answer is $D$.
$BT$ stands for $Bacillus$ $thuringiensis$,which is a bacterium used as a bio-pesticide.
Baculoviruses are pathogens that attack insects and other arthropods,used as biological control agents.
$IARI$ stands for Indian Agricultural Research Institute.
$KVIC$ stands for Khadi and Village Industries Commission,not 'Khadi Gram Vikas'. Therefore,option $D$ is mismatched.

(D) The statement '$Polysporum$ is a yeast' is false.
$Trichoderma$ $polysporum$ is actually a fungus (a filamentous fungus),not a yeast.
It is used for the commercial production of Cyclosporin $A$,which acts as an immunosuppressive agent in organ transplant patients.
Other options are correct:
$1$. Microorganisms are widely used in industries to produce enzymes like lipases,proteases,and pectinases.
$2$. Proteases and lipases are added to detergents to help remove oily and proteinaceous stains from clothes.
$3$. Microorganisms like $Ashbya$ $gossypii$ are used for the industrial production of vitamins (e.g.,Vitamin $B_2$ or Riboflavin).

(D) The correct answer is $D$.
$1$. Antibiotics were discovered by Alexander Fleming (Penicillin).
$2$. Curd is produced by the action of Lactic Acid Bacteria $(LAB)$ like Lactobacillus on milk.
$3$. Butyric acid is produced by the bacterium Clostridium butylicum.
$4$. Cyclosporin-$A$ is an immunosuppressive agent produced by the fungus Trichoderma polysporum,not Ashbya gossypii. Ashbya gossypii is used for the commercial production of Vitamin $B_2$ (Riboflavin).

(A) The correct matches are as follows:
$(1)$ Silage is a type of fermented, high-moisture stored fodder which can be fed to cattle, thus $(1-Q)$.
$(2)$ Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures during sewage treatment, thus $(2-R)$.
$(3)$ Biogas is produced by the anaerobic metabolism of organic waste by methanogens, thus $(3-S)$.
$(4)$ $BOD$ (Biochemical Oxygen Demand) is a measure of the amount of oxygen required by aerobic microorganisms to decompose organic matter in water, which indicates the level of water pollution, thus $(4-P)$.
Therefore, the correct sequence is $(1-Q), (2-R), (3-S), (4-P)$.

(C) The correct matches are as follows:
$(1)$ $LAB$ (Lactic Acid Bacteria) is responsible for $(R)$ Lactic acid production.
$(2)$ $Propionibacterium$ $shermanii$ is used in the production of $(S)$ Swiss cheese.
$(3)$ $Acetobacter$ $aceti$ is used for the production of $(U)$ Acetic acid.
$(4)$ $Clostridium$ $butyricum$ is used for the production of $(V)$ Butyric acid.
$(5)$ $Pseudomonas$ is involved in $(P)$ Quantum (often associated with specific metabolic pathways or bioremediation contexts in advanced studies).
$(6)$ $Azospirillum$ is a $(Q)$ Free-living $N_2$-fixer.
Therefore, the correct sequence is $(1-R), (2-S), (3-U), (4-V), (5-P), (6-Q)$.

(B) Statement $A$ is true because hydrogen is considered a clean and efficient fuel source.
Statement $R$ is also true because certain photosynthetic microorganisms,such as cyanobacteria and green algae,can produce hydrogen gas $(H_2)$ through biological processes by capturing solar energy and converting it into chemical energy stored in the bonds of $H_2$.
Since the production of hydrogen by these microorganisms is a primary reason why hydrogen is being explored as a sustainable biological fuel,$R$ provides the correct explanation for $A$.

(C) Methanogenic bacteria (e.g.,$Methanobacterium$) produce methane (biogas) from organic waste,which serves as a significant source of energy.
Photosynthetic bacteria (e.g.,$Cyanobacteria$ or $Purple$ $sulfur$ $bacteria$) can be used in bio-photovoltaic cells or for hydrogen production,which are also considered potential sources of energy.
Therefore,both $A$ and $B$ are correct.

(D) The correct answer is $D$.
$1$. Statins are produced by the yeast $Monascus purpureus$ and act as blood-cholesterol lowering agents.
$2$. Cyclosporin $A$ is produced by the fungus $Trichoderma polysporum$ and is used as an immunosuppressive agent in organ transplant patients.
$3$. Streptokinase is produced by the bacterium $Streptococcus$ and is used as a 'clot buster' for removing clots from the blood vessels of patients who have undergone myocardial infarction.
$4$. $Monascus purpureus$ produces statins, not riboflavin. Riboflavin is produced by fungi like $Ashbya gossypii$ or $Eremothecium ashbyii$. Therefore, the pair 'Monascus - Produces riboflavin' is mismatched.

(B) The correct matches are as follows:
$(A)$ Citric acid is produced by the fungus $Aspergillus$ $niger$ $(iii)$.
$(B)$ Cyclosporin $A$ is an immunosuppressive agent produced by the fungus $Trichoderma$ $polysporum$ $(i)$.
$(C)$ Statins are blood-cholesterol lowering agents produced by the yeast $Monascus$ $purpureus$ $(iv)$.
$(D)$ Butyric acid is produced by the bacterium $Clostridium$ $butylicum$ $(ii)$.
Therefore, the correct matching is $A-(iii), B-(i), C-(iv), D-(ii)$.
The correct option is $(B)$.

(C) The correct matches are as follows:
$1$. $(A)$ Saccharomyces cerevisiae is used for the commercial production of ethanol $(iii)$.
$2$. $(B)$ Monascus purpureus produces statins, which are blood-cholesterol lowering agents $(iv)$.
$3$. $(C)$ Trichoderma polysporum is the source of cyclosporin $A$, an immuno-suppressive agent $(i)$.
$4$. $(D)$ Propionibacterium shermanii is responsible for the ripening of Swiss cheese $(ii)$.
Therefore, the correct sequence is $A-(iii), B-(iv), C-(i), D-(ii)$.

$(A)$ Correct: Colostrum is the initial milk produced by the mother during the first few days of lactation, which is rich in antibodies, especially $IgA$, providing passive immunity to the newborn.
$(B)$ Incorrect: Chikungunya is a viral disease caused by the Chikungunya virus, which is transmitted to humans by infected mosquitoes, not by a bacterium.
$(C)$ Correct: Tissue culture, specifically meristem culture, is a widely used technique to produce virus-free plants because the meristematic tissue is typically free from viral infection.
$(D)$ Incorrect: Beer is produced by the fermentation of cereal grains like barley malt using yeast $(Saccharomyces \text{ } cerevisiae)$, not by the distillation of grape juice (which is used for wine/brandy).
Therefore, statements $(B)$ and $(D)$ are wrong. Thus, there are $2$ wrong statements.

(A) The correct answer is $A$.
Alcohol production involves the process of fermentation,which is carried out by yeast ($Saccharomyces$ $cerevisiae$) using the enzyme complex $Zymase$,not $Nitrogenase$.
$Nitrogenase$ is an enzyme involved in biological nitrogen fixation in prokaryotes.
$Pectinase$ and $cellulase$ are used to clarify fruit juices.
$Amylase$ is used in the textile industry for desizing fabrics.
$Lipase$ is used in detergent formulations to remove oily stains from laundry.

(C) : Coliform bacteria are commonly used as a bacterial indicator of the sanitary quality of foods and water. They are not involved in the production of vinegar. Vinegar is produced by the bacterium $Acetobacter$ $aceti$.

(C) Methanogens are anaerobic bacteria that produce methane $(CH_4)$ as a metabolic byproduct.
They are commonly found in the rumen (a part of the stomach) of cattle,where they help in the breakdown of cellulose.
They are also found in anaerobic sludge or slurry in biogas plants,where they facilitate the production of biogas from organic waste.
Therefore,both options $A$ and $B$ are correct.

(C) The correct matches are as follows:
$(1)$ Baculovirus: These are pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus $Nucleopolyhedrovirus$ $(d)$.
$(2)$ Trichoderma polysporum: This is a fungus that is used as a source of the immunosuppressive agent Cyclosporin-$A$ $(c)$.
$(3)$ Statins: These are blood-cholesterol lowering agents produced by the yeast $Monascus$ $purpureus$ $(b)$.
$(4)$ $BT$ Cotton: This is a genetically modified crop that contains the $cry$ gene derived from the bacterium $Bacillus$ $thuringiensis$ $(a)$.
Therefore,the correct matching is $1-d, 2-c, 3-b, 4-a$.

(C) - Aspergillus niger is a fungus (mold),not a bacterium. Thus,statement $A$ is incorrect.
$R$ - Lactobacillus is a bacterium (lactic acid bacteria),not a fungus. Thus,statement $R$ is incorrect.
Therefore,both statements $A$ and $R$ are incorrect.

(D) Assertion $(A)$ is correct: Alexander Fleming discovered the first antibiotic,penicillin,from the mold Penicillium notatum.
Reason $(R)$ is incorrect: Methanogens are anaerobic bacteria that produce methane (biogas) in anaerobic conditions,such as in the rumen of cattle or sewage treatment plants. The fermentation of malted cereals and fruit juices to produce ethanol is carried out by yeast,specifically Saccharomyces cerevisiae (brewer's yeast).

(D) is correct: The dough used for making foods such as dosa and idli is fermented by bacteria. During fermentation,$CO_2$ gas is produced,which gets trapped in the dough,causing it to puff up.
$R$ is incorrect: $LAB$ stands for Lactic Acid Bacteria. These bacteria are beneficial to humans as they grow in milk and convert it into curd. They improve the nutritional quality of curd by increasing vitamin $B_{12}$ content and also play a beneficial role in checking disease-causing microbes in our stomach. They do not damage the stomach.

(B) The correct matches are as follows:
$1$. $Saccharomyces$ $cerevisiae$ (Brewer's yeast) is used for the industrial production of ethanol $(a \to iii)$.
$2$. $Monascus$ $purpureus$ (a yeast) produces statins, which act as blood cholesterol-lowering agents $(b \to iv)$.
$3$. $Trichoderma$ $polysporum$ (a fungus) produces cyclosporin $A$, which is used as an immunosuppressive agent in organ transplant patients $(c \to i)$.
$4$. $Propionibacterium$ $sharmanii$ is used for the ripening of Swiss cheese, producing large holes due to the production of a large amount of $CO_2$ $(d \to ii)$.
Thus, the correct sequence is $(a \to iii), (b \to iv), (c \to i), (d \to ii)$.

(C) Microbes are not involved in the primary treatment of sewage,which is a physical process involving filtration and sedimentation to remove large and small particles.
Secondary treatment (biological treatment) involves the growth of aerobic microbes to consume organic matter.
Anaerobic sludge digesters use anaerobic bacteria to digest the sludge produced during secondary treatment.
Microbes are also used in the production of various bioactive molecules such as cyclosporin $A$ and statins.
Therefore,microbes are used in $2, 3,$ and $4$.