Microbes In Human Welfare

\textit{Lactobacillus} is a heterotrophic bacterium that ferments lactose in milk to produce lactic acid, leading to curd formation.
It ferments lactose in milk, producing lactic acid and causing the milk to curdle.

Step 1 (A): (A) MALT (Mucosa-Associated Lymphoid Tissue) is a component of the immune system found in mucosal linings such as the respiratory tract, gut, and urogenital tract. It provides localized immunity at the mucosal surfaces. (B) Cytokine barriers refer to proteins like interferons secreted by virus-infected cells that protect non-infected cells from further viral infection. (C) The diagnostic test for AIDS is the ELISA test. It works on the principle of antigen-antibody interaction, detecting HIV antibodies in the blood. (D) Bone marrow produces lymphocytes while the thymus is where T-lymphocytes mature. Together, they generate a functional immune system capable of defending the body.

Step 1: Cyanobacteria like \emph{Anabaena}, \emph{Nostoc}, and \emph{Oscillatoria} are free-living nitrogen-fixing bacteria found in aquatic and terrestrial habitats. Step 2: These microbes fix atmospheric nitrogen into usable forms, enriching the soil. They are used in rice fields to enhance fertility without the use of chemical fertilizers.

Step 1: (1) With distillation: Whisky or rum
(2) Without distillation: Wine or beer

Step 1: Lady bird beetle is used in biological control of aphids. → (i) → (c)
Step 2: Mycorrhiza refers to a symbiotic association of fungi with plant roots; Glomus is a genus of mycorrhizal fungi. → (ii) → (d)
Step 3: Trichoderma is a fungal genus used in biological control. → (iii) → (b)
Step 4: Methanobacterium is involved in methane (biogas) production. → (iv) → (a)

Aspergillus sp., particularly Aspergillus niger, is widely used for the industrial production of citric acid due to its efficiency in fermenting sugars into citric acid. Streptococcus, Clostridium, and Trichoderma are not typically used for this purpose.

Pectinases break down pectin, a component of plant cell walls that causes turbidity. Proteases remove proteins that also contribute to cloudiness, resulting in clearer juices.

Step 1: Monascus purpureus produces statins, which are used as cholesterol-lowering drugs.
Step 2: These compounds inhibit HMG-CoA reductase, an enzyme involved in cholesterol synthesis.
Step 3: Hence, the correct organism is Monascus purpureus.

Streptokinase, used as a clot-buster in myocardial infarction patients, is produced by the bacterium Streptococcus.

Swiss cheese gets its characteristic holes due to CO₂ production by the bacterium Propionibacterium shermanii, not by fungi. Hence, Assertion is true and Reason is false.

Swiss cheese contains holes due to carbon dioxide produced by Propionibacterium shermanii, not fungi. Hence, the assertion is correct but the reason is incorrect.

Large holes in Swiss cheese are formed by Propionibacterium shermanii, which ferments lactic acid to produce carbon dioxide gas, creating the characteristic 'eyes' or holes. Streptococcus pneumoniae causes pneumonia, Monascus purpureus is used in red yeast rice, and Trichoderma polysporum produces cyclosporin A, none of which are involved in Swiss cheese production.

Step 1 (A):

MALT (Mucosa-Associated Lymphoid Tissue) is a component of the immune system found in mucosal linings such as the respiratory tract, gut, and urogenital tract. It provides localized immunity at the mucosal surfaces.
Cytokine barriers refer to proteins like interferons secreted by virus-infected cells that protect non-infected cells from further viral infection.
The diagnostic test for AIDS is the ELISA test. It works on the principle of antigen-antibody interaction, detecting HIV antibodies in the blood.
Bone marrow produces lymphocytes while the thymus is where T-lymphocytes mature. Together, they generate a functional immune system capable of defending the body. Step 2 (B):

See the filled table above in the question section.
Baculoviruses are used as biological control agents because they are species-specific, do not harm non-target organisms, and are safe for the environment. They infect only specific insect pests.

Step 1: Cyanobacteria like \emph{Anabaena}, \emph{Nostoc}, and \emph{Oscillatoria} are free-living nitrogen-fixing bacteria found in aquatic and terrestrial habitats. Step 2: These microbes fix atmospheric nitrogen into usable forms, enriching the soil. They are used in rice fields to enhance fertility without the use of chemical fertilizers.

Step 1: (1) With distillation: Whisky or rum
(2) Without distillation: Wine or beer

Cyclosporin A is an immunosuppressive drug widely used during organ transplantation to prevent graft rejection. It is obtained from the fungus Trichoderma polysporum. This molecule acts by inhibiting the activity of T-cells, thereby suppressing the immune response.

Step 1: Biogas plants are indeed more prevalent in rural areas due to easy availability of cattle dung — Assertion is true.
Step 2: Cattle dung contains Methanobacterium, which helps in methane production — Reason is true.
Step 3: The presence of Methanobacterium in gobar is the reason biogas plants are suitable for rural areas — so Reason explains Assertion.

Clostridium species are anaerobic bacteria known for their role in producing butyric acid as a metabolic by-product in fermentation processes.

Step 1: The primary effluent obtained after sedimentation is transferred to large aeration tanks where it is subjected to secondary (biological) treatment.
Step 2: In these tanks, air is pumped to facilitate the vigorous growth of aerobic microbes, especially bacteria and protozoa, which form flocs (masses of bacteria and fungal filaments).
Step 3: These microbes digest the organic matter in the effluent, significantly reducing the biochemical oxygen demand (BOD), which is an indicator of organic pollution.
Step 4: Once the BOD is sufficiently reduced, the effluent is passed into a settling tank where the flocs settle as activated sludge.
Step 5: Part of this activated sludge is recycled back to the aeration tank as inoculum, and the rest is sent for anaerobic digestion or dried and used as manure.

Step 1: Lady bird beetle is used in biological control of aphids. → (i) → (c)
Step 2: Mycorrhiza refers to a symbiotic association of fungi with plant roots; Glomus is a genus of mycorrhizal fungi. → (ii) → (d)
Step 3: Trichoderma is a fungal genus used in biological control. → (iii) → (b)
Step 4: Methanobacterium is involved in methane (biogas) production. → (iv) → (a)

Anaerobic bacteria that decompose cellulosic material (like plant matter) in environments lacking oxygen carry out anaerobic digestion or fermentation. This process typically results in the production of several gases, including carbon dioxide (CO(_2)), methane (CH(_4)), and hydrogen (H(_2)). These gases are the primary components of biogas produced from the anaerobic breakdown of organic matter. Option includes CH(_3) (methyl radical), which is not a stable end product of this process. Option includes NH(_3) (ammonia), which is produced during the breakdown of nitrogen-containing compounds, not primarily from cellulose. Option includes H(_2)O (water), Cl(_2) (chlorine gas, which is not biologically produced in this context), and H(_2)S (hydrogen sulfide), which can be produced under certain anaerobic conditions, but CO(_2) and CH(_4) are more significant products of cellulose breakdown. Option correctly lists the major gaseous products of anaerobic digestion of cellulosic material.

Step 1: Understanding the Concept:
The shift from chemical to organic farming is driven by the negative environmental impacts of synthetic fertilizers.
Step 2: Detailed Explanation:
1. Environmental Safety: Chemical fertilizers often leach into water bodies, causing eutrophication and soil degradation. Bio-fertilizers are non-polluting and eco-friendly.
2. Sustainability and Soil Health: Bio-fertilizers maintain the natural nutrient cycle and improve soil structure and water-holding capacity. They are a low-cost, renewable source of nutrients, whereas chemical fertilizers are expensive and non-renewable.
Step 3: Final Answer:
Advantages include environmental protection (no pollution) and long-term improvement of soil health and sustainability.

Step 1: Understanding the Concept:
Different microbes have specialized roles in nutrient cycling within the soil.
Step 2: Detailed Explanation:
1. Bacteria: \textit{Rhizobium} forms symbiotic associations with legume roots to fix atmospheric nitrogen. Free-living bacteria like \textit{Azotobacter} and \textit{Azospirillum} also fix nitrogen directly into the soil.
2. Fungi: Fungi form symbiotic associations with plants called Mycorrhiza (e.g., genus \textit{Glomus}). The fungus absorbs phosphorus from the soil and passes it to the plant. It also provides resistance to root-borne pathogens and salinity.
3. Cyanobacteria: Blue-green algae like \textit{Anabaena}, \textit{Nostoc}, and \textit{Oscillatoria} can fix atmospheric nitrogen. In paddy fields, they serve as an important bio-fertilizer and also add organic matter to the soil.
Step 3: Final Answer:
Microbes include bacteria (fix nitrogen), fungi (absorb phosphorus), and cyanobacteria (fix nitrogen and add organic matter).

Step 1: Understanding the Concept:
Unlike chemical fertilizers, bio-fertilizers use living microorganisms to provide nutrients to plants.
Step 2: Detailed Explanation:
Bio-fertilizers are substances containing living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promote growth by increasing the supply or availability of primary nutrients to the host plant. They primarily consist of bacteria, fungi, and cyanobacteria.
Step 3: Final Answer:
Bio-fertilizers are living organisms (like bacteria or fungi) that enhance the fertility of the soil by providing nutrients like nitrogen and phosphorus.

Step 1: Understanding the Concept:
Secondary treatment of sewage is a biological process involving the use of microbes to reduce the organic load of wastewater.
Step 2: Detailed Explanation:
Assertion (A): During secondary treatment, the primary effluent is agitated in large aeration tanks. This allows vigorous growth of useful aerobic microbes into flocs. Flocs are indeed masses of bacteria associated with fungal filaments to form mesh-like structures. This statement is true.
Reason (R): While the microbes in flocs do perform aerobic respiration, they consume the organic matter (BOD) dissolved in the effluent. The term "solid waste" generally refers to the grit and debris removed during primary treatment (physical separation). Flocs do not digest the "solid waste" in the context of sewage treatment terminology; they digest dissolved or colloidal organic matter. Thus, the reason is technically false or inaccurate in its description.
Step 3: Final Answer:
Assertion is true, but the Reason is false regarding the digestion of "solid waste." Option (C) is correct.