Past Questions — 2024

Organic manures are broadly classified into two categories based on their nutrient concentration: Bulky Organic Manures and Concentrated Organic Manures. 1. **Concentrated Organic Manures**: These are derived from animal or plant sources and have a higher percentage of nutrients (especially Nitrogen and Phosphorus) compared to bulky manures. Examples include oil cakes (like Groundnut cake), animal meals (like Fish meal), and mineral-rich organic residues (like Bone meal). 2. **Bulky Organic Manures**: These contain small percentages of nutrients but are applied in large quantities to improve soil structure and organic matter. Examples include Farm Yard Manure (FYM), Compost, and Vermicompost. Analyzing the options: - **Groundnut cake (a)**: An oil cake rich in Nitrogen; it is a concentrated organic manure. - **Bone meal (b)**: Rich in Phosphorus and Calcium; it is a concentrated organic manure. - **Fish meal (d)**: Rich in Nitrogen and Phosphorus; it is a concentrated organic manure. - **Vermicompost (c)**: Produced through the action of earthworms on organic waste. While high in quality, it is low in nutrient concentration per unit weight compared to cakes or meals and is applied in bulk. Therefore, it is a bulky organic manure, not a concentrated one.

Potassium (K), commonly applied as Potash, plays a critical role in enhancing the overall health and resilience of plants. It acts as an activator for over 60 enzymes and regulates the opening and closing of stomata, which helps the plant manage water stress. Specifically, regarding pest and disease resistance: 1. Structural Strength: Potassium promotes the synthesis of lignin and cellulose, thickening the cell walls, which creates a physical barrier that makes it harder for fungal hyphae and insects to penetrate the plant tissue. 2. Osmotic Regulation: It improves the plant's ability to maintain turgor and manage osmotic pressure, reducing the physiological stress that often makes plants susceptible to opportunistic pathogens. 3. Biochemical Defense: It enhances the production of defense-related proteins and secondary metabolites. Comparing other options: - Nitrogen (c) promotes vegetative growth; however, excessive nitrogen often leads to succulent, soft tissues that are more attractive and susceptible to pests and fungal infections (e.g., aphids and powdery mildew). - Phosphorus (b) is essential for root development and energy transfer (ATP), but it is not the primary nutrient associated with immediate disease resistance. - Sulphur (d) is vital for protein synthesis and oil production, but its role in general pest/disease resistance is secondary compared to the structural and regulatory role of Potassium.

Plant nutrients are categorized based on the quantity required by the plant for growth and development into Macronutrients and Micronutrients. 1. **Macronutrients**: These are required in relatively large amounts. They include: - Primary Macronutrients: Nitrogen (N), Phosphorus (P), and Potassium (K). - Secondary Macronutrients: Calcium (Ca), Magnesium (Mg), and Sulfur (S). 2. **Micronutrients**: These are required in very small (trace) amounts but are essential for plant health. They include: Iron (Fe), Manganese (Mn), Boron (B), Molybdenum (Mo), Copper (Cu), and Zinc (Zn). Evaluating the options: - Option (a) N (Nitrogen) is a primary macronutrient. - Option (b) Zn (Zinc) is a micronutrient. - Option (c) Ca (Calcium) is a secondary macronutrient. - Option (d) Mg (Magnesium) is a secondary macronutrient. Therefore, Zinc (Zn) is the only micronutrient among the given options.

CPCRI stands for the Central Plantation Crops Research Institute. It is a premier research institution under the Indian Council of Agricultural Research (ICAR). The headquarters of CPCRI is located in Kasargod, Kerala. The institute focuses on the improvement of plantation crops such as coconut, arecanut, cocoa, and cashew. Analysis of options: - Option (a) Rajahmundry, Andhra Pradesh: Not the location of CPCRI. - Option (b) Kasargod, Kerala: Correct location of the CPCRI headquarters. - Option (c) Trivandrum, Kerala: While Kerala has many agricultural centers, the main CPCRI campus is in Kasargod. - Option (d) Kochi, Kerala: Not the location of CPCRI.

Ethylene is a gaseous plant hormone involved in fruit ripening and senescence. The biosynthesis of ethylene occurs via the Yang Cycle. The process begins with the amino acid Methionine, which is converted into S-adenosyl-L-methionine (SAM) by the enzyme SAM synthetase. SAM is then converted to 1-aminocyclopropane-1-carboxylic acid (ACC) by the enzyme ACC synthase, and finally, ACC is converted to ethylene by ACC oxidase. Analysis of other options: - Cystine: A sulfur-containing amino acid, but not the direct precursor for ethylene. - Purine: These are nitrogenous bases found in DNA and RNA, not amino acids. - Proline: An amino acid often associated with stress responses in plants, but not involved in ethylene synthesis.

Blossom End Rot (BER) is a physiological disorder commonly found in tomatoes, peppers, and eggplants. It is characterized by a sunken, leathery, dark brown or black spot at the blossom end (bottom) of the fruit. 1. Why Calcium (Ca) is the cause: Calcium is essential for the structural integrity of cell walls (as calcium pectate). Because calcium is immobile within the plant and moves primarily via the transpiration stream (xylem), any disruption in water uptake or a lack of available calcium in the soil leads to a deficiency in the rapidly growing fruit tissues, causing cell collapse and necrosis. 2. Why other options are incorrect: - Boron deficiency typically causes death of the growing point (meristem), hollow stems, or distorted fruit, but not the specific bottom-end rot seen in BER. - Sulphur deficiency generally manifests as general chlorosis (yellowing) of young leaves. - Potassium deficiency typically results in marginal scorching or necrosis of older leaves and poor fruit quality/size, but not localized blossom-end necrosis.

Step-by-step reasoning: 1. Definition of Organic Compounds: In chemistry and biology, organic compounds are defined as chemical compounds that contain carbon-hydrogen bonds. Carbon is the fundamental building block of all known life on Earth. 2. Role of Carbon: Carbon has the unique ability to form four stable covalent bonds (tetravalency), allowing it to create long chains, branched structures, and rings. This versatility is essential for forming complex organic molecules such as carbohydrates, lipids, proteins, and nucleic acids (DNA/RNA). 3. Analysis of other options: (a) Nitrogen is found in proteins and nucleic acids, but not all organic compounds contain nitrogen. (b) Phosphorus is found in ATP and nucleic acids, but is not the primary constituent of all organic matter. (c) Potassium is a vital macronutrient and cofactor for enzymes, but it exists primarily as an inorganic ion (K+) within the plant cell and is not a structural constituent of organic molecules. Therefore, Carbon is the most fundamental and essential constituent of organic compounds.

Papaya (Carica papaya) exhibits different sex expressions: dioecious (separate male and female plants), monoecious (male and female flowers on the same plant), and gynodioecious (plants that bear either female flowers or hermaphrodite flowers). 1. **Pusa Dwarf**: This is a well-known gynodioecious variety developed by IARI. Gynodioecious varieties are highly preferred in commercial cultivation because they ensure fruit set through the presence of hermaphrodite plants, which can self-pollinate or cross-pollinate with female plants, leading to higher yield stability. 2. **Other Options**: While other 'Pusa' series varieties exist, Pusa Dwarf is specifically cited in pomological literature as a gynodioecious cultivar. In many commercial contexts, the selection of gynodioecious types is critical to avoid the 'male plant problem' where too many male plants reduce the overall yield of the orchard.

In floriculture, the size of the Gladiolus corm is directly proportional to the quality, number of florets, and the overall vigor of the spike. Corms are generally categorized by size: small, medium, and large. For commercial production of high-quality flowers, corms with a diameter of 2.5 cm or more are preferred. Corms smaller than 2 cm often produce poor quality spikes or may not flower at all in the first season. While 3cm or 4cm corms would also produce good flowers, the standard minimum threshold for 'good quality' commercial production is typically cited as 2.5 cm in agricultural textbooks and extension guidelines. Therefore, 2.5 cm is the recognized benchmark for ensuring a high-quality bloom.

The pungency (spiciness) of chilli peppers (Capsicum spp.) is caused by a group of alkaloids called capsaicinoids, the most prominent and potent of which is Capsaicin. Capsaicin binds to the TRPV1 receptors in the mouth, which normally detect heat, sending a signal to the brain that creates the sensation of burning. Analysis of other options: - Capsanthin: This is the primary carotenoid pigment responsible for the red color of ripe chillies, not the pungency. - Lycopene: This is a red carotenoid pigment found predominantly in tomatoes and watermelons. - Carotene: This is a general term for a class of pigments (like beta-carotene) found in carrots and other vegetables, responsible for orange/yellow colors and acting as a precursor to Vitamin A.

In Pomology, citrus seeds (including mandarin orange) are known to be recalcitrant or semi-recalcitrant. This means they lose viability rapidly if they dry out. To ensure the highest germination percentage, citrus seeds should be sown immediately after they are extracted from the fruit. Drying the seeds (as suggested in option c) or storing them for long periods (as suggested in option d) leads to a significant drop in viability and germination rates. Furthermore, mandarin seeds do not have a deep physiological dormancy that requires a specific dormancy-breaking treatment (unlike some temperate fruits), making immediate sowing the standard practice for rootstock production.

Spongy tissue is a physiological disorder specifically associated with Mango (Mangifera indica). It is characterized by the development of soft, spongy, and often brownish tissue around the stone (endocarp) of the fruit. This condition is primarily caused by calcium deficiency and is often linked to the use of certain cultivars or improper nutrient management during fruit development. It results in a poor-quality fruit that is unmarketable. Comparing other options: - Apple: Common physiological disorders include 'Bitter Pit' (calcium deficiency) or 'Water Core', but not spongy tissue. - Orange: Common issues include 'Citrus Decline' or various fungal rots, but spongy tissue is not a characteristic disorder. - Banana: Common issues include 'Panama Wilt' or 'Sigatoka', but not spongy tissue.

In post-harvest physiology, fruits are categorized into two groups based on their ripening patterns: Climacteric and Non-climacteric. 1. **Climacteric Fruits**: These fruits exhibit a sharp rise in ethylene production and a corresponding increase in respiration rate during the ripening process. They can be harvested when mature but unripe and will continue to ripen off the plant. Examples include Guava, Mango, Banana, Papaya, and Jackfruit. 2. **Non-climacteric Fruits**: These fruits do not show a burst of ethylene or a rise in respiration during ripening. They must ripen fully on the plant to achieve maximum quality and do not ripen significantly after harvest. Examples include Citrus fruits (lemon, orange), Grapes, Strawberries, and Pineapple. Analyzing the options: - **Guava (a)**: Climacteric. - **Citrus (b)**: Non-climacteric. It does not show a respiratory burst during ripening. - **Jackfruit (c)**: Climacteric. - **Mango (d)**: Climacteric.

Strawberry (Fragaria × ananassa) is primarily propagated vegetatively through specialized stems called runners (also known as stolons). 1. **Runners (Stolons):** These are horizontal stems that grow along the soil surface. At certain nodes along the runner, adventitious roots and shoots develop, creating a new daughter plant genetically identical to the parent. This is the most common and efficient method of natural and commercial propagation for strawberries. 2. **Why other options are incorrect:** - **Suckers:** These are shoots that arise from the base of the stem or from underground roots (common in Banana or Date Palm), which is not the primary propagation method for strawberries. - **Cuttings:** While some plants are propagated via stem or leaf cuttings, strawberries are not typically propagated this way commercially. - **Root cutting:** This involves planting a piece of the root to generate a new plant (common in some ornamental shrubs), which is not the standard method for strawberry propagation.

Nitrogen-fixing bacteria are categorized based on their relationship with host plants. 1. **Azotobacter (Option b):** These are aerobic, free-living (non-symbiotic) bacteria found in the soil. They fix atmospheric nitrogen independently of any host plant, making them the correct answer. 2. **Rhizobium (Option a):** These are symbiotic bacteria that form nodules on the roots of leguminous plants. They cannot fix nitrogen effectively in a free-living state. 3. **Anabaena (Option c):** While Anabaena can fix nitrogen, it is a genus of Cyanobacteria (blue-green algae), not a 'bacteria' in the context of typical soil bacterial classification for this specific question type, and it often exists in symbiotic relationships (e.g., with the water fern Azolla). 4. **Azospirillum (Option d):** These are associative symbiotic bacteria. They live in close association with the roots of grasses and cereals but do not form nodules; they are not strictly 'free-living' in the same sense as Azotobacter, as they rely on root exudates for energy.

Step-by-step reasoning: 1. The question asks for the term used when chemical fertilizers are applied through modern irrigation systems. 2. 'Fertigation' is a portmanteau of 'Fertilization' and 'Irrigation'. It refers to the process of dissolving water-soluble fertilizers into an irrigation system (such as drip or sprinkler irrigation) to deliver nutrients directly to the plant root zone. 3. Analysis of other options: (a) 'Chemigation' is a general term sometimes used for applying chemicals, but 'Fertigation' is the specific, standard technical term for fertilizers in agriculture. (c) 'Nitridation' is a metallurgical process used to harden the surface of a metal by diffusing nitrogen into it. (d) 'Irrigation' refers only to the application of water to the soil, not specifically the application of fertilizers. Therefore, option (b) is the correct technical term.

To determine the most efficient earthworm for vermicomposting in tropical regions, we must evaluate the environmental preferences and metabolic rates of the species listed: 1. **Eudrilus eugeniae (African Nightcrawler):** This species is native to tropical regions. It is highly prized for vermicomposting in warm climates because it has a very high growth rate, high reproduction rate, and a high capacity for organic matter decomposition. It thrives in temperatures between 25°C and 30°C, making it the most efficient choice for tropical zones. 2. **Eisenia fetida (Red Wiggler):** While this is the most commonly used species globally for vermicomposting due to its hardiness, it is a temperate species. It prefers cooler temperatures (15-25°C) and can suffer high mortality rates or reduced efficiency in the extreme heat of tropical regions unless strictly climate-controlled. 3. **Perionyx excavatus:** This is a tropical species and is often used in Asia, but it generally has a slower decomposition rate and lower biomass production compared to Eudrilus eugeniae. 4. **Bimastos parvus:** This is not a primary species used in commercial or large-scale vermicomposting operations. Conclusion: Because Eudrilus eugeniae combines tropical adaptation with superior decomposition speed and biomass production, it is considered the most efficient for tropical regions.

Pheromone traps are highly effective tools in Integrated Pest Management (IPM) for monitoring and controlling specific insect pests. In cucurbits (gourds, melons, cucumbers), the Fruit Fly (e.g., Bactrocera spp.) is a major pest that attacks the fruit. Sex pheromones (such as Methyl Eugenol) are used to attract male fruit flies into traps, thereby disrupting the mating cycle and reducing the population. Why other options are incorrect: - b. Mites: Mites are tiny arachnids; they are typically controlled using acaricides or biological control agents, not pheromone traps. - c. Aphids: Aphids are sap-sucking insects that reproduce parthenogenetically (asexually) for much of their life cycle; pheromone traps are not a standard or effective method for their control. - d. Beetle: While some beetles are attracted to traps, the most common and commercially standardized use of pheromone traps in cucurbit crops for mass trapping and monitoring is specifically targeted at Fruit Flies.

In grape cultivation, training systems are used to manage the canopy for optimal sunlight penetration, aeration, and ease of harvest. 1. **Bower System (Pandora System):** This is the most commonly used training system in India and many other regions for commercial grape production. It involves creating a horizontal overhead trellis (a 'pergola' or 'canopy') where the vines grow and spread. This system maximizes the use of space, provides better sunlight distribution to the bunches, and allows for easier spraying and harvesting. 2. **Kniffin System:** This is a simpler system where the main stem is trained vertically and then pruned to produce lateral shoots. While used, it is less common for high-density commercial production compared to the Bower system. 3. **Head System:** This is a low-training system where the vine is kept short and bushy. It is rarely used in modern commercial viticulture as it limits yield and makes management difficult. 4. **Telephone System:** This is a variation of the trellis system (similar to Y-trellis) where the vine is split into two arms. While efficient for certain cultivars, it is not as universally 'most common' as the Bower system in the context of general agricultural exams focusing on commercial grape production.

Buttoning in cauliflower refers to the premature formation of a small, compact curd (resembling a button) before the plant has reached sufficient vegetative growth. This physiological disorder is primarily caused by a deficiency of Boron (B). Boron is essential for cell wall synthesis, pollen germination, and the proper development of the apical meristem. When Boron is deficient, the growth of the shoot apex is stunted, leading to the premature initiation of the curd. Analysis of other options: - Ca (Calcium) deficiency typically leads to 'Tip Burn' in cauliflower, where the edges of the inner curd leaves turn brown and die. - N (Nitrogen) deficiency results in general stunting of the plant, pale yellow leaves (chlorosis), and a failure to produce a large curd, but not specifically 'buttoning'. - Fe (Iron) deficiency causes interveinal chlorosis in young leaves, which does not result in the buttoning phenomenon.

Cytokinins are a class of plant growth substances that promote cell division (cytokinesis). They can be categorized into natural and synthetic forms. 1. **Zeatin (Option a):** This is the most well-known naturally occurring cytokinin. It was first isolated from corn (Zea mays) kernels. It is synthesized in the roots and transported to the shoots. 2. **Kinetin (Option b):** This was the first cytokinin discovered, but it is a synthetic compound (originally isolated from autoclaved herring sperm DNA) and is not naturally produced by plants in significant quantities. 3. **BA (Benzyladenine) (Option c):** This is a synthetic cytokinin widely used in plant tissue culture to induce shoot formation. 4. **NAA (Naphthalene acetic acid) (Option d):** This is not a cytokinin at all; it is a synthetic Auxin used to induce rooting. Therefore, Zeatin is the only naturally occurring cytokinin among the given options.

In orchard management, different planting systems are used to optimize space and plant density. 1. **Hexagonal (or Equilateral Triangle) System**: In this system, plants are placed at the corners of equilateral triangles. This arrangement allows for more efficient use of space compared to the square system. Mathematically, the hexagonal system accommodates approximately 15% more plants than the square system for the same spacing between plants. 2. **Square System**: This is the simplest system where plants are placed at the corners of a square. It serves as the baseline for calculating plant density. 3. **Quincunx System**: This is essentially a square system with an additional plant in the center of each square. While it increases the number of plants initially, the center plant is usually removed once the main plants grow and shade it, so it is not characterized by a permanent 15% increase in the same way the hexagonal system is. 4. **Rectangular System**: This is a variation of the square system where the distance between rows is greater than the distance between plants within a row, typically resulting in fewer plants per unit area than the square system.

A pre-plant (or pre-emergence) weedicide is applied to the soil before the crop is planted or before the crop emerges from the soil to prevent weed seeds from germinating. 1. **Basalin (d)**: This is a soil-applied pre-emergence herbicide (specifically a benazolin derivative) used primarily in crops like rice to control annual grasses and sedges. It is applied before the crop emerges, making it a pre-plant/pre-emergence weedicide. 2. **Atrazine (b)**: While Atrazine can be used pre-emergence, it is most commonly categorized as a selective systemic herbicide used post-emergence in maize and sugarcane. 3. **Simazine (c)**: Similar to Atrazine, it is a selective herbicide often used for pre- and post-emergence control, but in the context of standard agricultural exam classifications, Basalin is the classic example of a pre-plant/pre-emergence soil sterilant/inhibitor. 4. **Stamp (a)**: This is not a standard recognized chemical name for a primary pre-plant weedicide in agricultural science. Therefore, Basalin is the most accurate answer for a pre-plant/pre-emergence weedicide among the given options.

In guava (Psidium guajava), there are typically three flowering seasons based on the climatic conditions of India: 1. Amrapali/Amra Bahar: Flowering occurs in January-February, and fruits mature in June-July. This is the most preferred crop for quality. 2. Mrig Bahar: Flowering occurs in June-July (during the monsoon), and fruits mature in November-December. This crop is generally more abundant but may be prone to pests and diseases due to high humidity. 3. Hasta Bahar: Flowering occurs in October-November, and fruits mature in February-March. Therefore, for Mrig Bahar, the flowering period is June-July.

Green manuring involves growing specific crops (usually legumes) and plowing them back into the soil to improve fertility. The timing of incorporation is critical for maximizing nutrient return: 1. Why Pre-flowering is correct: The pre-flowering stage is the ideal time for incorporation because the plant has accumulated the maximum amount of biomass (vegetative growth) and nitrogen, but the nutrients have not yet been diverted toward seed production. At this stage, the plant tissues are succulent and tender, which ensures rapid decomposition by soil microorganisms, leading to a quicker release of nutrients for the succeeding crop. 2. Why other options are incorrect: - Seedling stage: The biomass produced is too low to provide significant organic matter or nutrients to the soil. - Fully mature stage: At maturity, the plant becomes woody (lignified), which slows down the decomposition process. Furthermore, a significant portion of the nitrogen and minerals is transferred from the leaves and stems into the seeds/pods, reducing the nutrient value of the green manure. - Drying stage: Once the plant dries, the microbial activity required for decomposition is hindered, and the organic matter is no longer 'green' or succulent, defeating the purpose of green manuring.