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Past Questions — 2024
To which one of the soil orders does black soils of India belong?
A)
Alfisol
B)
Inceptisol
C)
Vertisol
D)
Oxisol
Step-by-step reasoning:
1. **Identification of Soil Type**: Black soils of India (also known as Regur soils) are characterized by a high content of expansive clay minerals, primarily montmorillonite.
2. **Defining Vertisols**: In the USDA Soil Taxonomy, 'Vertisols' are defined as soils that have a high content of swelling clays, which cause the soil to shrink and crack during dry periods and swell when wet. The name is derived from the Latin word 'vertere', meaning 'to turn', referring to the self-plowing nature of these soils due to the shrink-swell cycles.
3. **Matching**: The physical and chemical properties of Indian black soils (high clay content, shrink-swell capacity, and dark color) align perfectly with the definition of the Vertisol order.
Evaluation of other options:
- **Alfisol**: These are forest soils with a clay-enriched subsoil and are typically found in humid regions; they do not exhibit the shrink-swell properties of black soils.
- **Inceptisol**: These are 'young' soils with minimal horizon development; while common in India (e.g., in the Himalayas), they are not the characteristic order for black soils.
- **Oxisol**: These are highly weathered tropical soils (common in the Amazon or parts of Africa) rich in iron and aluminum oxides, typically red or yellow in color, unlike the nutrient-rich black soils.
The colorimeter is based on-
A)
Bragg’s law
B)
Lambert-Beer’s law
C)
Plank’s law
D)
Kirchoff’s law
A colorimeter is an analytical instrument used to measure the concentration of a colored compound in a solution by measuring the absorbance of a specific wavelength of light. It operates based on the Lambert-Beer Law (or Beer-Lambert Law), which states that the absorbance of a solution is directly proportional to the concentration of the absorbing species and the path length of the light through the sample (A = εcl).
Why other options are incorrect:
- Bragg's Law: Relates to the diffraction of X-rays through a crystal lattice.
- Plank's Law: Describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium.
- Kirchoff's Law: In the context of optics/thermal radiation, it states that for an arbitrary body in thermal equilibrium, emissivity equals absorptivity; in electronics, it relates to current and voltage in circuits.
In Tobacco, the first GMO crop, what type of resistance has been developed?
A)
Insect resistance
B)
Herbicide resistance
C)
Disease resistance
D)
Herbicide tolerant
Tobacco (Nicotiana tabacum) was one of the earliest plants used in genetic engineering experiments. Specifically, the development of insect-resistant tobacco was a landmark achievement in biotechnology. This was achieved by introducing genes from Bacillus thuringiensis (Bt), a soil bacterium, which produces Cry proteins that are toxic to specific insect pests (like the tobacco budworm). While herbicide resistance was developed later in other crops (like soybean and corn), the pioneering work in transgenic tobacco focused heavily on insect resistance to demonstrate the feasibility of the technology. Note: While some early research explored other traits, 'Insect resistance' is the standard academic answer for the first major GMO trait developed in tobacco in the context of agricultural biotechnology exams.
Dropsy disease in human being is caused by which weed?
A)
Argemone mexicana
B)
Digera arvensis
C)
Convolvulus arvensis
D)
Pluchea lanceolata
Dropsy is a medical condition characterized by severe edema (swelling) caused by the accumulation of fluid in the tissues, often resulting from cardiac failure or renal issues. In the context of weed science and toxicology, 'Epidemic Dropsy' is caused by the consumption of mustard oil contaminated with the seeds of Argemone mexicana (Mexican Poppy). The seeds of Argemone mexicana contain a toxic alkaloid called sanguinarine, which interferes with the oxidation of pyruvic acid, leading to the accumulation of aspartic acid in the blood and subsequent capillary leakage and edema.
Analysis of other options:
- b. Digera arvensis: A common weed of cultivated lands, not associated with causing dropsy.
- c. Convolvulus arvensis (Field Bindweed): A perennial weed that affects crops but is not known to cause dropsy in humans.
- d. Pluchea lanceolata: A weed species that does not produce the toxins responsible for epidemic dropsy.
For production of wheat foundation seed, an isolation distance is-
A)
1m
B)
3m
C)
5m
D)
10m
In seed technology, isolation distance is the minimum distance required between two fields of different varieties of the same crop to prevent cross-pollination and maintain genetic purity. Wheat (Triticum aestivum) is a predominantly self-pollinated crop, meaning the risk of cross-pollination is very low. According to standard seed certification norms (such as those provided by the OECD and national seed certification agencies):
1. For Foundation Seed of wheat, the recommended isolation distance is 3 meters.
2. For Certified Seed of wheat, the isolation distance is typically 3 meters as well, though some guidelines may allow for smaller distances due to the high rate of self-pollination.
Comparing the options:
- 1m: Too short to ensure purity for foundation seed standards.
- 3m: The standard accepted isolation distance for wheat foundation seed.
- 5m and 10m: These distances are generally reserved for cross-pollinated crops (like maize or sunflower) or specific hybrid seeds, and are unnecessary for a self-pollinated crop like wheat.
Which GIS- derived factor is commonly integrated into the Revised Universal Soil Loss Equation (RUSLE) model for soil loss prediction?
A)
Vegetation density
B)
Topographic factor
C)
Crop type
D)
Soil pH
The Revised Universal Soil Loss Equation (RUSLE) is expressed as A = R × K × LS × C × P.
1. **R (Rainfall-Runoff Erosivity Factor):** Based on precipitation data.
2. **K (Soil Erodibility Factor):** Based on soil texture, structure, and organic matter.
3. **LS (Topographic Factor):** This is the product of the Slope Length (L) and Slope Steepness (S). In modern soil conservation studies, this factor is almost exclusively derived using Geographic Information Systems (GIS) by analyzing a Digital Elevation Model (DEM) to calculate slope and flow accumulation.
4. **C (Cover and Management Factor):** Based on vegetation/crop type.
5. **P (Support Practice Factor):** Based on conservation practices like contouring.
While vegetation density (Option a) and crop type (Option c) influence the 'C' factor, they are often derived from land-use maps or field surveys. The 'Topographic factor' (Option b) is the quintessential GIS-derived component because it requires spatial terrain analysis (DEM) to be calculated accurately across a landscape. Soil pH (Option d) is not a direct factor in the RUSLE equation.
LEISA is related to-
A)
Organic farming
B)
Natural farming
C)
Inorganic farming
D)
Dry farming
LEISA stands for 'Low External Input and Sustainable Agriculture'. It is a farming management system that emphasizes the use of local resources and biological processes to maintain soil fertility and control pests, thereby minimizing or eliminating the use of synthetic (external) inputs like chemical fertilizers and pesticides. Because it focuses on reducing external chemical inputs and promoting ecological sustainability, it is fundamentally related to the principles of Organic Farming.
Why other options are incorrect:
- b. Natural farming: While similar, Natural Farming (like ZBNF) is often a more restrictive subset that avoids all cultivation/tillage and external inputs entirely, whereas LEISA is a broader framework for sustainable management.
- c. Inorganic farming: This refers to conventional farming relying on synthetic chemicals, which is the exact opposite of the LEISA philosophy.
- d. Dry farming: This is a method of farming in areas with low rainfall without irrigation; it is a climatic adaptation strategy, not a resource-input management system like LEISA.
Which of the following nutrient is essential for oil synthesis in rapeseed and mustard?
A)
Calcium
B)
Sulphur
C)
Boron
D)
Nitrogen
Rapeseed and mustard belong to the Brassicaceae family, which are known as 'sulphur-loving' crops. Sulphur is a critical constituent of several amino acids (methionine and cysteine) and is essential for the synthesis of proteins and oils. Specifically, sulphur is required for the activity of enzymes involved in the synthesis of fatty acids and the production of glucosinolates, which are characteristic of oilseed crops. A deficiency in sulphur leads to a significant reduction in the oil content and overall seed yield in these crops.
Why other options are incorrect:
- Calcium (a): Primarily involved in cell wall structure and signaling, not directly in oil synthesis.
- Boron (c): Essential for pollen germination, fruit set, and sugar transport, but not the primary driver of oil synthesis.
- Nitrogen (d): Essential for vegetative growth and protein synthesis, but excessive nitrogen can sometimes lead to increased biomass at the expense of oil percentage.
Atmometer is used to measure-
A)
Transpiration
B)
Water requirement
C)
Rate of water evaporation
D)
Evapotranspiration
An Atmometer is a meteorological instrument specifically designed to measure the rate of evaporation of water from a free water surface. It typically consists of a porous ceramic cup or a similar absorbent material that allows water to be drawn up by capillary action and then evaporated into the air.
Why other options are incorrect:
- a. Transpiration: This is the process of water movement through a plant and its evaporation from aerial parts (mainly leaves). It is measured using a Potometer.
- b. Water requirement: This is a calculated value based on the crop's needs, soil type, and climate, not measured by a single instrument.
- d. Evapotranspiration: This is the combined loss of water from the soil surface (evaporation) and plant surfaces (transpiration). It is measured using a Lysimeter.
Restriction of export and import of seeds was envisaged through-
A)
Seed Act, 1968
B)
Seed Control Order, 1983
C)
New Seed Policy
D)
Seed Bill
The Seed Control Order, 1983 was specifically enacted to regulate the import and export of seeds to ensure that the quality of seeds entering or leaving the country is maintained and to prevent the introduction of pests and diseases. While the Seed Act of 1966 (often cited as 1968 in some contexts, though the primary act is 1966) focuses on the quality control and certification of seeds within the domestic market, the Seed Control Order provides the administrative mechanism to restrict and monitor the movement of seeds across international borders.
Breakdown of options:
- a. Seed Act, 1966/1968: Primarily deals with seed certification, labeling, and quality standards within India.
- b. Seed Control Order, 1983: Specifically designed for the restriction and regulation of import and export of seeds.
- c. New Seed Policy: These are general policy frameworks (like the 1988 policy) that guide the direction of seed production and distribution but are not the legal instrument for restriction.
- d. Seed Bill: A bill is a proposed law and not an enacted order or act used for enforcement.
Parthenium hysterophorus can be biologically controlled by-
A)
Chrysomella spp
B)
Dactylopius tomentosus
C)
Zygogramma bicolorata
D)
Neochetina spp
Parthenium hysterophorus (commonly known as Congress grass or Carrot grass) is an invasive weed. Its most effective biological control agent is the mealybug 'Dactylopius tomentosus'. This insect feeds on the sap of the plant, causing chlorosis and eventually leading to the death of the weed.
Analysis of other options:
- Chrysomella spp: These are leaf beetles primarily used for the biological control of St. John's wort (Hypericum perforatum).
- Zygogramma bicolorata: This is a leaf-eating beetle used specifically for the biological control of Parthenium's relative or other specific weeds, but more famously associated with the control of Parthenium in some contexts, however, Dactylopius tomentosus is the primary and most widely recognized biological agent for Parthenium in standard agricultural textbooks.
- Neochetina spp: These are cecidomyiid flies used for the biological control of Water Hyacinth (Eichhornia crassipes).
Nitrification bacteria is-
A)
Obligate heterotrophs
B)
Facultative heterotrophs
C)
Obligate autotrophs
D)
Facultative autotrophs
Nitrification is a two-step biological process where ammonia is converted to nitrite and then to nitrate. The bacteria involved in this process (such as Nitrosomonas and Nitrobacter) are chemoautotrophs.
1. **Autotrophs**: They are called autotrophs because they derive their carbon from inorganic carbon dioxide (CO2) rather than organic compounds.
2. **Chemoautotrophs**: They obtain energy from the oxidation of inorganic nitrogen compounds (ammonia and nitrite) rather than from sunlight (photoautotrophs).
3. **Obligate**: They are 'obligate' because they are restricted to this specific mode of nutrition; they cannot switch to using organic carbon sources for energy or growth (unlike facultative organisms).
Therefore, nitrification bacteria are classified as obligate autotrophs.
- Options (a) and (b) are incorrect because heterotrophs require organic carbon sources.
- Option (d) is incorrect because these bacteria cannot switch their metabolic pathways to heterotrophy.
Most commonly used herbicide to kill broad leaved weeds in wheat field is-
A)
Isoproturon
B)
2,4-D
C)
Alachor
D)
Butachlor
Step-by-step reasoning:
1. Analysis of the requirement: The question asks for a herbicide specifically used to control 'broad-leaved weeds' (dicots) in a 'wheat field' (a monocot crop).
2. Evaluating Option (b) 2,4-D: 2,4-D (2,4-Dichlorophenoxyacetic acid) is a systemic selective herbicide. It mimics the plant growth hormone auxin, causing uncontrolled growth and death in broad-leaved plants while leaving grasses and cereals (like wheat) largely unaffected. It is the gold standard for post-emergence control of broad-leaved weeds in wheat.
3. Evaluating Option (a) Isoproturon: This is primarily used to control grassy weeds (like Phalaris minor) in wheat, not broad-leaved weeds.
4. Evaluating Option (c) Alachlor: This is a pre-emergence herbicide used mainly in maize, soybean, and sugarcane to control annual grasses and some broad-leaved weeds, but it is not the primary choice for broad-leaved weeds in wheat.
5. Evaluating Option (d) Butachlor: This is predominantly used in rice fields to control grasses and sedges.
Conclusion: 2,4-D is the most common and specific choice for broad-leaved weed control in wheat.
According to fertilizer control order 1957, Biuret content in urea should not exceed-
A)
1.0% by weight
B)
1.5% by weight
C)
2.0 % by weight
D)
2.5% by weight
Under the Fertilizer Control Order (FCO) 1985 (which governs the standards for fertilizers in India, often referenced in the context of the 1957 act/regulations), the quality specifications for Urea are strictly defined to prevent crop toxicity. Biuret is a byproduct formed during the manufacture of urea (through the condensation of two urea molecules). High concentrations of biuret are phytotoxic and can cause leaf burn or stunted growth in sensitive crops. To ensure safety and quality, the FCO stipulates that the biuret content in urea must not exceed 1.0% by weight. Options b, c, and d are incorrect as they exceed the legal safety limit established by the regulatory authority.
Which element is the non-metal among the following micronutrients?
A)
Iron
B)
Manganese
C)
Zinc
D)
Boron
To solve this question, we must categorize the listed micronutrients based on their chemical properties (Metal vs. Non-metal).
1. **Iron (Fe):** A transition metal. It is a metallic element.
2. **Manganese (Mn):** A transition metal. It is a metallic element.
3. **Zinc (Zn):** A transition metal. It is a metallic element.
4. **Boron (B):** A metalloid (often categorized with non-metals in basic chemical classifications of plant nutrients). Unlike the other three options, Boron does not possess metallic properties such as high electrical conductivity or the tendency to form cations in the same way as transition metals; it is typically absorbed by plants as boric acid or borate anions.
Among the given options, Iron, Manganese, and Zinc are clearly metals, leaving Boron as the only non-metal/metalloid element.
In universal soil loss equation(A=RKLSCP) where K denotes-
A)
Soil erodibility factor
B)
Slope gradient
C)
Soil Erosivity
D)
Soil cover
The Universal Soil Loss Equation (USLE) is used to predict the long-term average annual rate of erosion. The formula is A = R × K × L × S × C × P.
Breakdown of the factors:
1. **A (Average Annual Soil Loss):** The amount of soil lost per unit area per year.
2. **R (Rainfall Erosivity Factor):** Measures the erosive power of rainfall (Option c is incorrect as R denotes erosivity).
3. **K (Soil Erodibility Factor):** This represents the inherent susceptibility of the soil to erosion based on its physical and chemical properties (texture, structure, organic matter, permeability). Therefore, Option a is correct.
4. **L (Slope Length Factor):** The length of the slope.
5. **S (Slope Gradient Factor):** The steepness of the slope (Option b is incorrect as S denotes gradient).
6. **C (Cover and Management Factor):** The effect of cropping and management practices on erosion (Option d is incorrect as C denotes cover).
7. **P (Support Practice Factor):** The effect of conservation practices like contouring or terracing.
Grass tetany is caused by deficiency of the following nutrient in forage crops:
A)
Ca
B)
S
C)
Mg
D)
Mn
Grass tetany, also known as hypomagnesemia, is a metabolic disorder occurring in ruminants (cattle and sheep) that graze on lush, rapidly growing spring pastures. It is caused by a deficiency of Magnesium (Mg) in the animal's blood. While the forage itself may contain some magnesium, the high potassium (K) and nitrogen levels in lush grass interfere with the absorption of Mg in the rumen, leading to a deficiency.
Analysis of options:
- a. Ca (Calcium): Deficiency leads to Milk Fever (Parturient Paresis), not grass tetany.
- b. S (Sulphur): Deficiency typically affects protein synthesis and growth but does not cause acute tetany.
- c. Mg (Magnesium): Correct. Low serum magnesium levels lead to neuromuscular hyperexcitability, muscle tremors, and convulsions (tetany).
- d. Mn (Manganese): Deficiency leads to conditions like Perosis or skeletal deformities, not acute tetany.
Tag used for foundation seed is-
A)
Golden yellow
B)
Blue
C)
Green
D)
White
Option A is correct: Golden yellow.
Gobar gas production was first started in-
A)
Germany
B)
Japan
C)
India
D)
U.S.A.
Gobar gas, scientifically known as biogas, is produced through the anaerobic digestion of organic matter (such as cattle dung). The first systematic production of biogas was pioneered in Germany. In 1859, Michael Faraday first described the production of methane from organic matter, but it was in Germany during the late 19th century that the first biogas plants were developed for practical use. Specifically, the first biogas plant was built in Germany in 1859 by researchers exploring the properties of methane. While India is currently one of the largest adopters of biogas technology for rural energy, the origin of the technology is European, specifically German. Therefore, option (a) is correct, while Japan, India, and the U.S.A. were later adopters or developers of the technology.
Head Quarter of International seed testing association is located at-
A)
China
B)
Switzerland
C)
Australia
D)
India
The International Seed Testing Association (ISTA) is the global authority for seed testing and certification. Its headquarters is located in Bassersdorf, Switzerland. ISTA's primary goal is to harmonize the rules and procedures for seed testing worldwide to facilitate the international trade of seeds.
Analysis of options:
- a. China: Not the headquarters of ISTA.
- b. Switzerland: Correct. The ISTA secretariat is based in Bassersdorf, Switzerland.
- c. Australia: Not the headquarters of ISTA.
- d. India: While India is a member of ISTA and has recognized seed testing laboratories, it does not host the international headquarters.
The quick seed viability test is-
A)
Tetrazolium test
B)
Germination test
C)
Field test
D)
Vigour test
The Tetrazolium (TZ) test is widely recognized as the 'quick' seed viability test because it provides results within 24 to 48 hours, whereas a standard germination test can take weeks.
1. **How it works**: The test uses 2,3,5-triphenyl tetrazolium chloride. Living tissues contain dehydrogenase enzymes that react with the colorless TZ solution, reducing it to a red-colored compound called 'formazan'. Therefore, seeds that stain red are considered viable, while those that remain colorless are dead.
2. **Why other options are incorrect**:
- **Germination test (b)**: This is the standard method to determine viability, but it is slow because it requires the seed to actually grow into a seedling.
- **Field test (c)**: This is an impractical method for rapid viability assessment as it is subject to environmental variables and takes a full growing cycle or emergence period.
- **Vigour test (d)**: Vigour refers to the seed's ability to emerge under stressful conditions. While related to viability, vigour tests (like the Accelerated Aging test) are used to determine the quality/strength of the seed, not just whether it is alive or dead.
Which one of the following is the biochemical test?
A)
Brick Gravel test
B)
Seed size
C)
First count
D)
Tetrazolium test
The Tetrazolium test (TZ test) is a biochemical method used to determine seed viability. It relies on the activity of dehydrogenase enzymes in living tissues. When seeds are soaked in a 2,3,5-triphenyl tetrazolium chloride solution, the dehydrogenase enzymes reduce the colorless TZ salt into a red-colored compound called formazan. Since this reaction is driven by cellular respiration (a biochemical process), it allows for the rapid assessment of seed viability without waiting for actual germination.
Why other options are incorrect:
- a. Brick Gravel test: This is a physical/mechanical test used to determine the hardness of seed coats (especially in legumes) to assess dormancy.
- b. Seed size: This is a physical characteristic/morphological measurement, not a biochemical test.
- c. First count: This is a part of the standard germination test (a biological/physiological test) where the number of germinated seeds is counted after a specific short interval to estimate the final germination percentage.
In the Universal Soil Loss Equation (USLE) , what does ‘LS’ factor represent?
A)
Land slope and soil type
B)
Land use and surface cover
C)
Length and steepness of slope
D)
Latitude and slope direction
The Universal Soil Loss Equation (USLE) is used to predict the long-term average annual rate of erosion. The formula is A = R × K × LS × C × P.
1. **A** is the average annual soil loss.
2. **R (Rainfall Erosivity Factor)**: Measures the erosive power of rain.
3. **K (Soil Erodibility Factor)**: Measures the susceptibility of soil particles to detachment.
4. **LS (Topographic Factor)**: This is a combined factor where 'L' represents the slope length and 'S' represents the slope steepness. As the length of the slope increases, runoff accumulates and gains velocity; as the steepness increases, the velocity of runoff increases, both leading to higher soil erosion.
5. **C (Cover Management Factor)**: Represents the effect of cropping and management practices.
6. **P (Support Practice Factor)**: Represents the effect of conservation practices like contouring or strip cropping.
Therefore, 'LS' specifically represents the length and steepness of the slope. Option (a) is incorrect because soil type is covered by 'K'. Option (b) is covered by 'C'. Option (d) is irrelevant to the USLE formula.
The C:P ratio for net immobilization of phosphorus is-
A)
>300:1
B)
<200:1
C)
<300:1
D)
>200:1
In soil science, the mineralization and immobilization of nutrients depend on the ratio of carbon to the specific nutrient (C:N, C:P, C:S) in the organic matter being decomposed by microorganisms.
1. **Mineralization** occurs when the organic matter contains more nutrients than the microbes need for their own growth, releasing the excess into the soil.
2. **Immobilization** occurs when the organic matter is nutrient-poor (high C:nutrient ratio), forcing microbes to scavenge inorganic nutrients from the soil solution to decompose the carbon, thereby making those nutrients unavailable to plants.
For Phosphorus (P), the critical C:P ratio is generally considered to be around 200:1.
- If the **C:P ratio is < 200:1**, net mineralization occurs (P is released).
- If the **C:P ratio is > 200:1**, net immobilization occurs (P is tied up by microbes).
Therefore, for net immobilization of phosphorus, the ratio must be greater than 200:1.
For tobacco crop, the preferred potassic fertilizer is-
A)
Potassium nitrate
B)
Potassium chloride
C)
Potassium sulphate
D)
Potassium iodate
Tobacco is a chloride-sensitive crop. The use of Potassium chloride (Muriate of Potash - MOP) can lead to the accumulation of chloride ions in the leaves, which adversely affects the quality of the cured tobacco, causes 'chloride burn,' and reduces the overall market value of the crop. Therefore, Potassium sulphate (Sulphate of Potash - SOP) is the preferred potassic fertilizer for tobacco because it provides the necessary potassium without introducing harmful levels of chloride.
Breakdown of options:
- a. Potassium nitrate: While usable, it is more expensive and primarily used in specialized fertigation rather than as the standard preferred potassic source.
- b. Potassium chloride: Avoided in tobacco due to chloride toxicity/sensitivity.
- c. Potassium sulphate: The ideal choice for chloride-sensitive crops like tobacco, grapes, and citrus.
- d. Potassium iodate: This is a micronutrient additive (usually for salt iodization) and not used as a primary potassic fertilizer for crop nutrition.