Explore topic-wise InterviewSolutions in .

The CORRECT choice is (a) Transgenic TOBACCO

The best explanation: Transgenic CROPS have genes of smoother crops, pest and herbicide resistance. E.g., Transgenic tomato (against Hornworm LARVAE) and Transgenic tobacco (against herbicides).

Right choice is (d) Wheat

The best I can explain: Smoother crops do not ALLOW the growth of weeds. For example, Sunflower, SOYBEAN, ALFALFA, Barley, Rye, SORGHUM, Sweet CLOVER. Rotation with smoother crops gives protection from the weeds.

The correct answer is (a) True

The EXPLANATION is: In paddy fields, cyanobacteria serve as an important bio-fertiliser by increasing SOIL fertility and adding organic matter to the soil. They can also be associated with the ROOTS of higher PLANTS to INCREASE their potential.

The correct answer is (a) Vesicular-arbuscular MYCORRHIZA

The explanation: VAM stands for Vesicular-arbuscular mycorrhiza. It is a type of ENDOMYCORRHIZA where FUNGUS SENDS its hyphal tips into cells as vesicles and arbuscules (branched MASSES).

Right OPTION is (b) Fungal symbiont ABSORBS nitrogen

Easiest explanation: Fungi are known to form symbiotic associations with plants known as MYCORRHIZA. Many members of genus Glomus form mycorrhiza. The fungal symbiont absorbs phosphorous from the soil and PASSES it on to the plant. Plants having such associations show resistance to root-borne pathogens and an overall increase in plant growth and development.

Right choice is (a) Phosphorus

Easy explanation: Presence of Phosphorous is essential for nitrogen FIXATION. Plants having symbiotic BACTERIA have HIGHER protein content. No EXTERNAL nitrogen fertilizer is required.

Right choice is (d) Lactobacillus

Easiest explanation: Cyanobacteria are AUTOTROPHIC microbes widely distributed in aquatic and TERRESTRIAL ENVIRONMENTS many of which can fix atmospheric NITROGEN like NOSTOC, Anabaena and Oscillatoria.

The correct answer is (a) Azotobacter

Easy explanation: Some of the aerobic nitrogen-fixing bacteria are Azotobacter and Beijerinckia. Some of the anaerobic nitrogen-fixing bacteria are Clostridium, Rhodospirillum and Rhodopseudomonas. SOIL is ENRICHED through exudation and FORMATION of NITRATES after their DEATH and decay.

The correct option is (d) XANTHOMONAS

The best EXPLANATION: Some of the free-living Nitrogen-fixing bacteria are-Azotobacter, Clostridium, Klebsiella and Beijerinckia. RHIZOBIUM, Xanthomonas and FRANKIA are some of the symbiotic Nitrogen-fixing bacteria.

The correct CHOICE is (b) False

To EXPLAIN I would say: The nodules on the root of some leguminous plants are in the symbiotic association with Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as NUTRIENT.

Correct choice is (b) Algae

For explanation I would SAY: Bio fertilisers are ORGANISMS that ENRICH the nutrient quality of the soil. The main sources of bio-fertilisers are BACTERIA, fungi and cyanobacteria.

Correct answer is (C) Increasing environmental pollution

The best explanation: There are a lot of problems associated with the overuse of chemical fertilisers like environmental pollution, soil pollution, THERMAL pollution, ETC. Therefore, there is a large pressure to switch to organic farming which includes the use of BIORESOURCES like bio-fertilisers which can be recycled.

Right CHOICE is (d) ENVIRONMENTAL Pollution

For explanation: With our present-day LIFESTYLES, environmental pollution is a major cause of concern. The use of CHEMICAL fertilisers to meet the ever-increasing demand for agricultural PRODUCE has contributed significantly to this pollution.

The correct option is (a) Sporeine

To EXPLAIN I WOULD SAY: Sporeine was developed in GERMANY and is the first commercially used bio-insecticide. Its other trade names are Dipel, Biostol and Thuricide.

Correct answer is (a) Arthropods

For EXPLANATION I would say: Baculoviruses are PATHOGENS that attack insects and other arthropods. They have SHOWN no negative impacts on plants, mammals, birds, fish or even on non-target insects.

Right choice is (a) It is a bacterium

To explain: Trichoderma SPECIES are free-living fungi that are very common in the ROOT ECOSYSTEMS. They are EFFECTIVE biocontrol agents of SEVERAL plant pathogens.

Right option is (c) Bt-cotton

Easiest explanation: Due to the development of VARIOUS methods of genetic engineering, in the last decade or so, scientists have introduced Bacillus thuringiensis TOXIN GENES into the plants. Bt-cotton is one such EXAMPLE, which is being cultivated in some STATES of our country.

Correct answer is (b) False

Explanation: When the bacteria are EATEN by the LARVA, then in its gut, the toxin is released and the larva gets killed. The bacterial DISEASE will kill the CATERPILLARS, but leave other insects unharmed.

The correct OPTION is (a) Bacillus thuringiensis

Explanation: Biocontrol agents are the organisms which are the natural enemies of INSECT pests or the disease-causing microbes which can be used for our own benefit. For example, BACTERIA Bacillus thuringiensis which can be introduced to control BUTTERFLY caterpillars.

The correct answer is (c) In the FORM of dried spores

Explanation: Bacillus thuringiensis is often available in SACHETS as dried spores which are mixed with water and SPRAYED onto VULNERABLE plants such as brassicas and fruit trees, where they are eaten by the insect LARVAE.

Correct OPTION is (B) Mosquitoes

The explanation is: The dragonflies are very useful to GET rid of mosquitoes. The very FAMILIAR beetle with red and black markings-the Ladybird is useful to get rid of aphids.

Right option is (B) Use of biocontrol measures will increase our dependence on chemical fertilizers

Explanation: In biological farming, farmers understand the webs of interaction between the myriad of ORGANISMS that constitute the field FLORA and fauna. They also become familiar with the life cycles, feeding habits, PESTS and predators of various life forms that inhabit the field. THUS, the use of biocontrol measures greatly reduces our dependence on chemical fertilizers.

Right option is (d) Air

The explanation: The CHEMICAL fertilisers have been POLLUTING our environment-soil, ground, water, FRUITS, vegetables and CROP PLANTS. Our soil is also polluted through our use of weedicides to remove weeds.

Correct choice is (a) True

The best EXPLANATION: The more variety a landscape has, the more sustainable it is. The organic FARMER works to CREATE a system where pests are not eradicated but INSTEAD are kept at manageable levels by a complex system of checks and BALANCES.

Right option is (b) Natural predation

Explanation: In agriculture, there is a method of controlling pests that relies on natural predation rather than INTRODUCED chemicals. A KEY BELIEF of the organic FARMER is that BIODIVERSITY furthers health and the use of chemicals sometimes kills both useful and harmful life forms.

The correct CHOICE is (a) Use of biological methods for controlling plant diseases

For explanation I WOULD say: Biocontrol REFERS to the use of biological methods for controlling plant diseases and pests. Fertilisers of biological origin are of TWO types-manures and bio-fertilizers.

Correct option is (d) Indian agricultural research INSTITUTE

For EXPLANATION: IARI stands for Indian agricultural research institute. It is located in New Delhi. This institute made the production of biogas at a very large scale POSSIBLE by GENERATING APPROPRIATE technologies for the production of biogas.

The correct option is (b) Biogas plant does not have an outlet

The best I can explain: The biogas plant has a 10-15 feet deep concrete TANK. A floating cover is placed over SLURRY which keeps on rising as the GAS is produced in the tank due to the microbial activity. The biogas plant has an outlet, which is connected to a PIPE to supply biogas to nearby houses. ALSO, the slurry can be removed and may be used as a fertiliser.

The CORRECT option is (c) Gobar gas

For EXPLANATION: The EXCRETA or DUNG of the cattle, commonly called gobar is rich in methanogens. THEREFORE, dung can be used for the generation of biogas, commonly called gobar gas.

Right CHOICE is (a) Substrate

Easiest EXPLANATION: The type of gas produced depends UPON the microbes and the organic substrates they utilise. For example, in the fermentation of DOUGH, cheese making and production of beverages, the main gas produced is CO2.

Right OPTION is (a) True

To ELABORATE: A lot of cellulosic material is present in the FOOD of cattle. In the rumen, these bacteria help in the breakdown of cellulose and play an IMPORTANT role in the nutrition of cattle.

Correct ANSWER is (d) Methanogens

To explain I WOULD SAY: The biogas producing bacteria are COLLECTIVELY known as methanogens and one such common bacterium is Methanobacterium. These bacteria are commonly found in the anaerobic sludge during the sewage treatment and also in the RUMEN of cattle.

Correct answer is (b) Cellulose

For explanation: Certain bacteria which produce biogas like the methanogens particularly GROW anaerobically on cellulosic MATERIAL to produce LARGE amounts of methane with CARBON DIOXIDE and hydrogen.

Correct answer is (d) H2O

Best EXPLANATION: Certain bacteria PRODUCE a mixture of gases such as methane, hydrogen sulphide and carbon DIOXIDE. These gases form BIOGAS and can be used as a source of energy as it is inflammable.

Correct OPTION is (b) ANAEROBIC SLUDGE digesters

To explain I WOULD say: In the secondary treatment, a small part of the activated sludge is pumped back into the aeration tank to serve as inoculum. The remaining major part of the sludge is pumped into large anaerobic sludge digesters.

Right OPTION is (a) MILLIONS

Easy EXPLANATION: Millions of gallons of waste water is treated in various sewage plants where microbes play a major role in decomposing the waste. This METHODOLOGY has been practised for a century, in almost all parts of the WORLD.

Right option is (C) Greater the BOD, lesser is the polluting potential of WATER

Easiest explanation: The sewage water is treated until the BOD is reduced. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water and thus, BOD is indirectly a MEASURE of the organic MATTER present in the water. The greater the BOD of waste-water more is its polluting potential.

The correct choice is (d) Masses of BACTERIA

Easiest explanation: The constant AGITATION of primary effluent ALLOWS vigorous growth of USEFUL aerobic microbes into flocs which are the masses of bacteria associated with FUNGAL filaments to form mesh-like structures.

The CORRECT ANSWER is (a) Initially floating debris is removed by distillation

For explanation: In PRIMARY treatment, initially floating debris is removed by sequential filtration. Then grit and SMALL pebbles are removed by sedimentation. All SOLIDS that settle form the primary sludge while the supernatant forms the effluent.

The correct option is (a) True

Explanation: The EFFLUENT from the primary SETTLING TANK is taken for secondary treatment. The primary effluent is then passed into large aeration TANKS where it is constantly agitated mechanically and the air is PUMPED into it.

Right ANSWER is (a) False

The explanation: Primary treatment involves the basic removal of PARTICLES- LARGE and small-from the sewage through filtration and sedimentation. These particles are removed further in VARIOUS stages.

Correct CHOICE is (b) Two

To explain: The TREATMENT of waste-water in STPs is carried out in two stages NAMELY primary treatment and secondary treatment. Treatment of waste-water is done by the heterotrophic microbes NATURALLY present in the sewage.

Right answer is (b) Human excreta

The EXPLANATION is: A major component of this waste-water is human excreta. This municipal waste-water is also called as sewage. It contains a large amount of ORGANIC MATTER and MICROBES. Many of which are pathogenic.

Right choice is (B) Sewage treatment plants

Easy explanation: STP stands for sewage treatment plants. Before the disposal of waste-WATER into the natural water bodies, sewage is treated in STPS to make it LESS polluting.