Ionic detergents contain a head group which is either positively or negatively charged. For example, the anionic detergent sodium dodecyl sulfate (SDS) carries a negatively charged sulfate group on a linear C12 hydrocarbon chain. It is also a strong detergent and will often irreversibly denature proteins.

Aspergillus produces citric acid through fermentation of starch and molasses.

Bioethanol is one of the most commonly used biofuels in transportation sector to reduce greenhouse gases. S. cerevisiae is the most employed yeast for ethanol production at industrial level though ethanol is produced by an array of other yeasts, bacteria, and fungi. 

The presence of E. coli in water indicates that, it has been contaminated with faecal matter. Thus, E. coli is commonly known as indicator of water pollution. Lemna and Eichhornia are free-floating hydrophytes, which remain in contact with water and air but not soil.

Azolla pinnata is a species of fern known by several common names, including feathered mosquito-fern and water velvet. It is native to much of Africa, Asia from China to Japan, India and the Philippines and parts of Australia. The leaves contain the Anabaena azollae, which is a symbiont that fixes nitrogen from the atmosphere that the fern can use. This gives the fern the ability to grow in habitats that are low in nitrogen. Rice farmers sometimes, keep this plant in their paddies, because it generates valuable nitrogen via its symbiotic Cyanobacteria. So, modern farmers can increase the yield of paddy up to 50% by the use of Cyanobacteriain Azolla pinnata.

Thus, the correct answer is option C.

Municipal waste-water which contains large amounts of organic matter is called sewage.

Before disposal, hence, sewage is treated in sewage treatment plants (STPs) by the heterotrophic microbes to make it less polluting.

Organochlorine pesticides are stable and stay in the environment for a long time. Pesticides such as hexachlorocyclohexane (HCH), endosulfan and DDT have been used for agricultural purposes. 

Solar radiation on the earth’s surface is abundant and truly a zero-carbon energy source. The solar energy needs to be harnessed using various efficient equipments, which has a very low carbon footprint. Various solar thermal energy harvesting techniques have been used which employ solar radiation incident on the optimal area with the help of concentrators.

The first genetically modified crop plant was produced in 1982, an antibiotic-resistant tobacco plant.The first field trials occurred in France and the USA in 1986, when tobacco plants were engineered for herbicude resistance.

The methanogenic bacteria are a large and diverse group that is united by three features:
1) They form large quantities of methane as the major product of their energy metabolism.
2) They are strict anaerobes.
3) They are members of the domain Archaea, or archaebacteria,  and only distantly related to the more familiar classical bacteria or eubacteria. Like the photosynthetic eubacteria, the methanogenic bacteria are related to each other primarily by their mode of energy metabolism but are very diverse with respect to their other properties.

Many proteins are produced in E.coli using the recombinant DNA technology. Among the options listed interferon which stimulates non-specific immunity against virus, tumours, bacteria and parasites has been successfully cloned and expressed in E.coli as early as 1986. Thus, the correct option is D.

Most vaccines against bacterial infections are effective at preventing disease, reactions can occur after vaccinations. Vaccines are available against tuberculosis, diphtheria, tetanus, pertussis, Haemophilus influenzae type B, cholera, typhoid, and Streptococcus pneumoniae.
A vaccine works by training the immune system to recognize and combat pathogens, either viruses or bacteria. To do this, certain molecules from the pathogen must be introduced into the body to trigger an immune response. These molecules are called antigens, and they are present on all viruses and bacteria.
Protein based subunit vaccines present an antigen to the immune system without viral particles, using a specific, isolated protein of the pathogen. A weakness of this technique is that isolated proteins, if denatured, may bind to different antibodies than the protein of the pathogen.

The “sharing” of DNA among living forms is well documented as a natural phenomenon. For thousands of years, genes have moved from one organism to another. For example, Agrobacterium tumefaciens, a soil bacterium known as ‘nature’s own genetic engineer’, has the natural ability to genetically engineer plants. It causes crown gall disease in a wide range of broad-leaved plants, such as apple, pear, peach, cherry, almond, raspberry, and roses. 

The bioconversion of starch into ethanol is a two-step process. The first step is saccharification, where starch is converted into sugar using an amylolytic microorganism or enzymes such as glucoamylase and amylase. The second step is fermentation, where sugar is converted into ethanol using Saccharomyces cerevisiae.

A Bio fertilizer is a substance which contains living microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Bio-fertilizers such asRhizobium, Azotobacter, Azospirilium and blue green algae (BGA) have been in use a long time. Blue green algae , Nostoc or Anabaena, fix atmospheric nitrogen and are used as inoculations for paddy crop grown both under upland and low-land conditions. 

Interferons are categorized as cytokines, small proteins that are involved in intercellular signaling. Interferon is secreted by cells in response to stimulation by a virus or other foreign substance, but it does not directly inhibit the virus’s multiplication. 

Methanogens can be also found in non-natural habitats such as landfills, digesters or biogas plants. There, the microbial community varies with the substrate. In biogas plants, due to hydrolysis of complex polymers to sugars and amino acids, followed by fermentation and acetogenesis, acetate, H₂ and CO₂ is produced as substrates for methanogenesis. 

Strains of Saccltarornyces cerevisiae is extensively used for leavening of bread. During fermentation, the yeasts produce alcohol and CO₂  which leaves the read porous.

Maximum application of animal cell culture technology is in the production of vaccines. Vaccines are chemical substances prepared from the proteins of other animals which confer immunity to a particular virus. Some of the vaccines synthesized biologically , through genetic engineering are vaccines for hepatitis B virus, vaccines for rabies virus, vaccines for poliovirus and vaccines for small pox virus, etc.