← Combined Technical (NG)
Past Questions — 2025
Which of the following is a characteristic of a successful entrepreneur in horticulture?
A)
Risk avoidance
B)
Proactive decision making and innovation
C)
Dependence on government subsidies only
D)
Resistance to change
Entrepreneurship, particularly in the field of horticulture, requires a mindset geared toward growth, efficiency, and adaptation.
1. Why Option (b) is correct: A successful entrepreneur must be 'proactive' to anticipate market trends (such as shifts in consumer demand for organic produce) and 'innovative' to implement new technologies (like drip irrigation, hydroponics, or greenhouse management) to increase yield and quality.
2. Why Option (a) is incorrect: Entrepreneurship inherently involves taking calculated risks. 'Risk avoidance' prevents a business from expanding or adopting new, more efficient methods, which is contrary to the entrepreneurial spirit.
3. Why Option (c) is incorrect: While subsidies can provide initial support, a sustainable and successful business cannot depend 'only' on government aid. Financial independence and revenue generation from market sales are essential for long-term viability.
4. Why Option (d) is incorrect: Horticulture is a dynamic field influenced by climate change, pests, and evolving market preferences. 'Resistance to change' leads to obsolescence and failure in a competitive agricultural market.
In tissue culture media, the primary role of auxins is to:
A)
Induce shoot formation
B)
Promote root initiation and callus formation
C)
Prevent microbial contamination
D)
Maintain osmotic balance
In plant tissue culture, the morphogenesis of an explant is primarily controlled by the ratio of two classes of phytohormones: auxins and cytokinins.
1. **Auxins** (e.g., NAA, IAA, 2,4-D) are primarily responsible for promoting cell division and elongation. In tissue culture, a high auxin-to-cytokinin ratio is used to induce the formation of roots (rhizogenesis) and the development of an unorganized mass of cells known as a callus.
2. **Cytokinins** (e.g., BAP, Kinetin) are primarily responsible for inducing shoot formation (caulogenesis). A high cytokinin-to-auxin ratio promotes shoot growth.
Evaluating the options:
- Option (a) is incorrect because shoot formation is the primary role of cytokinins.
- Option (b) is correct as auxins trigger rooting and callus induction.
- Option (c) is incorrect because microbial contamination is prevented by sterilizing agents (like ethanol or bleach) and aseptic techniques, not hormones.
- Option (d) is incorrect because osmotic balance is maintained by sugars (like sucrose) and salts in the medium.
Which of the following is commonly used as a refrigerant in cold storage in India?
A)
R-134a (Tetrafluoroethane)
B)
Ammonia (NH3)
C)
Carbon dioxide (CO2)
D)
Water (H2O)
In the context of large-scale industrial cold storage and agricultural warehouses in India, Ammonia (NH3) is the most commonly used refrigerant. This is due to several factors: 1. Thermodynamic Efficiency: Ammonia has a very high latent heat of vaporization, making it highly efficient for large-scale cooling. 2. Cost-Effectiveness: It is significantly cheaper than synthetic fluorocarbons. 3. Environmental Impact: Ammonia has zero Ozone Depletion Potential (ODP) and zero Global Warming Potential (GWP), making it an environmentally sustainable choice compared to CFCs or HCFCs.
Analysis of other options:
- R-134a (Tetrafluoroethane): While common in domestic refrigerators and car air conditioners, it is less common for massive industrial cold storage due to higher costs and lower efficiency compared to ammonia.
- Carbon dioxide (CO2): Used in specialized 'Controlled Atmosphere' (CA) storage to slow down ripening, but it is not the primary refrigerant for general cold storage cooling systems.
- Water (H2O): Water is used as a coolant in chilled water systems or ice plants, but it is not a refrigerant in the sense of a substance undergoing a phase change in a compression cycle to provide cooling.
In order to create modified atmosphere around fresh fruits and vegetables in modified atmosphere packaging, the type of packaging material used is:
A)
Freely permeable
B)
Semi permeable
C)
Non permeable
D)
Rigid plastic with air vents
Modified Atmosphere Packaging (MAP) is a technique used to extend the shelf life of fresh produce by altering the composition of the gases (typically oxygen, carbon dioxide, and nitrogen) surrounding the product.
1. Why 'Semi permeable' is correct: Fresh fruits and vegetables are living tissues that continue to respire after harvest, consuming O2 and releasing CO2. To maintain an optimal atmosphere, the packaging material must be semi-permeable. This allows for a controlled exchange of gases—letting some O2 in and some CO2 out—to prevent the produce from becoming anaerobic (which leads to off-flavors and spoilage) while still reducing the overall respiration rate to slow down senescence.
2. Why other options are incorrect:
- Freely permeable: If the material were freely permeable, the internal atmosphere would remain identical to the outside air, failing to 'modify' the atmosphere.
- Non permeable: If the material were completely non-permeable, the produce would quickly consume all available oxygen and build up toxic levels of CO2, leading to anaerobic respiration and rapid decay.
- Rigid plastic with air vents: While vents allow gas exchange, they are generally too coarse to create the precise, controlled gas concentrations required for true MAP; they provide ventilation rather than a modified atmosphere.
Which of the following is a commonly used interculture implement?
A)
Disc harrow
B)
Hoe
C)
Seed drill
D)
Tractor-mounted plough
Interculture refers to the cultivation operations carried out in the space between rows of crops after they have been sown and before they are harvested. The primary objectives of interculture are weed control, soil aeration, and moisture conservation.
1. **Hoe (Correct):** A hoe is a classic interculture implement used for weeding and loosening the soil between crop rows without damaging the main plants. It is specifically designed for these 'in-between' operations.
2. **Disc harrow (Incorrect):** This is a primary or secondary tillage implement used for breaking up clods, mixing crop residue, and preparing the seedbed before planting.
3. **Seed drill (Incorrect):** This is a sowing implement used to place seeds at a specific depth and spacing in the soil; it is used during the planting phase, not for interculture.
4. **Tractor-mounted plough (Incorrect):** A plough is a primary tillage implement used for initial soil inversion and breaking of the land to prepare it for cropping.
The father of modern genetics, Gregor Mendel, worked primarily on:
A)
Rice
B)
Maize
C)
Pea
D)
French Bean
Gregor Mendel, an Austrian monk, is recognized as the father of modern genetics due to his pioneering work on inheritance. Between 1856 and 1863, he conducted extensive hybridization experiments using the garden pea plant (Pisum sativum). He chose the pea plant because it has easily identifiable contrasting traits (e.g., tall vs. short, purple vs. white flowers), a short life cycle, and the ability to be self-pollinated or cross-pollinated. Through these studies, he formulated the fundamental laws of inheritance: the Law of Segregation and the Law of Independent Assortment. Options a (Rice), b (Maize), and d (French Bean) are incorrect because, while they are plants used in later genetic research, they were not the primary subjects of Mendel's foundational experiments.
A piece of potato is placed in a concentrated sugar solution for 30 minutes. After this, the potato becomes flaccid and shrinks. What is the reason?
A)
Water moved into the potato cells by osmosis.
B)
Water moved out of the potato cells by osmosis.
C)
Sugar moved into the potato cells by diffusion.
D)
Sugar moved out of the potato cells by diffusion
This question tests the understanding of osmosis and tonicity in plant cells.
1. **Osmosis Definition**: Osmosis is the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) across a selectively permeable membrane.
2. **The Scenario**: A potato piece (containing cell sap with a certain concentration of solutes) is placed in a 'concentrated sugar solution'. This means the external environment is **hypertonic** relative to the interior of the potato cells.
3. **Direction of Flow**: Because the sugar solution has a lower water potential than the potato cells, water moves out of the vacuole and cytoplasm of the potato cells into the surrounding solution to reach equilibrium.
4. **Result**: The loss of water leads to a decrease in turgor pressure. The cell membrane pulls away from the cell wall (plasmolysis), causing the potato tissue to become flaccid and shrink in size.
**Why other options are incorrect:**
- **Option a**: Water would only move into the cells if the external solution were hypotonic (e.g., distilled water), which would make the potato turgid, not flaccid.
- **Option c & d**: While diffusion occurs, the primary cause of the rapid shrinking and flaccidity in this biological context is the movement of water (osmosis), not the movement of sugar molecules, which move much more slowly across the cell membrane.
Which nutrient plays a key role in ATP formation and energy transfer in plants?
A)
Nitrogen
B)
Phosphorus
C)
Potassium
D)
Sulphur
Step-by-step reasoning: 1. ATP (Adenosine Triphosphate) is the primary energy currency of the cell. Its chemical structure consists of an adenine base, a ribose sugar, and three phosphate groups. 2. The energy in ATP is stored in the high-energy phosphate bonds; when these bonds are broken (hydrolysis), energy is released for cellular processes. 3. Phosphorus is the essential element that forms these phosphate groups. 4. Analysis of other options: (a) Nitrogen is primarily used in proteins, chlorophyll, and nucleic acids. (c) Potassium acts as an osmoticum and activates enzymes but is not a structural component of ATP. (d) Sulphur is found in certain amino acids (cysteine, methionine) and vitamins, but not in the energy-transfer molecule ATP.
The mechanism responsible for the ascent of sap in plants is:
A)
Root pressure
B)
Capillarity
C)
Cohesion-tension theory
D)
Active transport
The 'ascent of sap' refers to the upward movement of water and dissolved minerals from the roots to the leaves in tall plants.
1. **Cohesion-Tension Theory (Correct):** This is the widely accepted scientific explanation. It posits that transpiration (evaporation of water from leaf stomata) creates a negative pressure (tension) at the top of the xylem. Because water molecules are polar, they stick to each other via hydrogen bonding (cohesion) and to the xylem walls (adhesion). This creates a continuous, unbroken column of water that is 'pulled' upward from the roots to the leaves, regardless of the tree's height.
2. **Root Pressure (Incorrect):** While root pressure helps push water up in small plants or during periods of low transpiration (causing guttation), it is insufficient to move water to the tops of tall trees (e.g., Redwoods).
3. **Capillarity (Incorrect):** Capillary action occurs in very narrow tubes, but the physical limits of capillarity can only lift water a few centimeters or meters, not the dozens of meters required for most trees.
4. **Active Transport (Incorrect):** Active transport requires ATP to move solutes against a concentration gradient. While it is used to load minerals into the xylem, the bulk flow of water itself is a passive process driven by the water potential gradient created by transpiration.
The pedigree method of selection involves:
A)
Selecting plants based on their physical appearance
B)
Keeping detailed records of the ancestry of selected plants
C)
Allowing random mating among plants
D)
Using molecular markers to select plants
The pedigree method is a widely used breeding technique for developing pure lines in self-pollinated crops. In this method, individual plants are selected in the segregating generations (usually starting from F2), and their progeny are grown in separate rows in subsequent generations. The key characteristic of this method is the maintenance of a detailed record (a 'pedigree') of the parent-offspring relationship. This allows the breeder to track the inheritance of desirable traits and discard lineages that show undesirable characteristics.
Why other options are incorrect:
- Option (a): While physical appearance (phenotype) is used to select plants, this is a general feature of most selection methods (like mass selection) and does not define the 'pedigree' aspect specifically.
- Option (c): Random mating is characteristic of population improvement or mass selection, whereas the pedigree method relies on controlled selfing and progeny testing.
- Option (d): Using molecular markers is known as Marker-Assisted Selection (MAS), which is a modern tool that can be used within a pedigree program but is not the definition of the pedigree method itself.
In plant breeding, backcrossing is used to:
A)
Introduce a new trait from a different species
B)
Remove undesirable traits from a variety
C)
Increase the yield potential of a variety
D)
Develop prolific varieties
Backcrossing is a plant breeding method used to transfer a specific desired trait (e.g., disease resistance) from a donor parent into an otherwise high-performing 'recurrent parent' variety. The process involves crossing the hybrid offspring back to the recurrent parent for several generations. This effectively 'washes out' or removes the undesirable traits and genetic baggage introduced by the donor parent, while retaining the specific target gene.
Analysis of other options:
- Option (a) is incorrect because introducing traits from different species usually involves interspecific hybridization or genetic engineering, not standard backcrossing.
- Option (c) is incorrect because while backcrossing can maintain yield, its primary purpose is trait transfer/purification, not the inherent increase of yield potential (which is usually achieved through selection or hybridization).
- Option (d) is incorrect as 'prolific varieties' (high productivity) are generally developed through mass selection, pedigree breeding, or hybrid vigor, rather than the specific mechanism of backcrossing.
The bulk method in plant breeding is primarily used for:
A)
Developing pure lines
B)
Releasing new hybrid varieties
C)
Increasing the frequency of desirable alleles in a population
D)
Producing genetically identical clones
The bulk method (or bulked population method) is a breeding technique used primarily in self-pollinated crops to develop new varieties. In this method, the F2 generation and subsequent generations (up to F5 or F6) are grown and harvested in 'bulk' without individual plant selection. Natural selection acts on the population over several generations, which increases the frequency of desirable alleles that provide a survival or yield advantage in a specific environment.
Why other options are incorrect:
- Option (a): While the bulk method eventually leads to the development of pure lines (after individual plant selection in later generations), its primary mechanism during the bulk phase is the shift in allele frequency via natural selection, not the immediate creation of pure lines.
- Option (b): Hybrid varieties are developed through controlled crossing of distinct inbred lines, not through the bulk method, which relies on selfing and natural selection.
- Option (d): Producing genetically identical clones is achieved through vegetative propagation or tissue culture (asexual reproduction), not through the sexual recombination and selection processes involved in the bulk method.
In plant breeding, the term heterosis refers to:
A)
Hybrid vigour leading to superior performance
B)
The process of self-pollination
C)
Genetic uniformity in a population
D)
The ability of a plant to adapt to various environmental conditions
Step-by-step reasoning: 1. Definition: Heterosis, commonly known as 'hybrid vigour', is the phenomenon where the progeny (F1 hybrid) of two genetically diverse parents exhibits superior traits (such as higher yield, faster growth, or better stress resistance) compared to both parents. 2. Mechanism: It is generally attributed to the masking of harmful recessive alleles (dominance hypothesis) or the synergistic effect of heterozygous gene combinations (overdominance hypothesis). 3. Evaluating options: Option (a) directly describes this phenomenon. Option (b) refers to autogamy, which often leads to inbreeding depression (the opposite of heterosis). Option (c) refers to homozygosity or genetic homogeneity, which is the goal of pure-line breeding, not heterosis. Option (d) refers to phenotypic plasticity or general adaptability, which is a different trait from the genetic superiority gained through hybridization.
Which of the following is a non-climacteric fruit?
A)
Mango
B)
Banana
C)
Pineapple
D)
Papaya
In post-harvest technology, fruits are classified into two categories based on their ripening patterns: climacteric and non-climacteric.
1. Climacteric fruits: These fruits exhibit a burst of ethylene production and a sharp increase in respiration rate during ripening. They can be harvested while mature but unripe and will continue to ripen off the plant. Examples include Mango, Banana, Papaya, Apple, and Tomato.
2. Non-climacteric fruits: These fruits do not show a significant increase in ethylene production or respiration rate after harvest. They must ripen fully on the plant to achieve maximum quality and sweetness, as they cannot ripen further once detached. Examples include Pineapple, Citrus fruits, Grapes, and Strawberries.
Analyzing the options:
- Mango (a): Climacteric
- Banana (b): Climacteric
- Pineapple (c): Non-climacteric
- Papaya (d): Climacteric
Therefore, Pineapple is the correct answer.
Which of the following is a common method for controlling post-harvest diseases in fruits?
A)
Hot water treatment
B)
Waxing
C)
Shrink wrapping
D)
Precooling
Step-by-step reasoning:
1. **Hot Water Treatment (HWT)**: This is a widely recognized physical method used to control post-harvest diseases and pests (such as fruit flies and fungal pathogens like anthracnose). By immersing fruits in water at a specific temperature for a set duration, the heat kills or inhibits the growth of pathogens on the surface and sometimes within the skin of the fruit without damaging the tissue.
2. **Waxing (Option b)**: While waxing helps reduce moisture loss (transpiration) and improves the appearance of the fruit, its primary purpose is to extend shelf life by reducing water loss, not specifically to control diseases (though some waxes may contain fungicides).
3. **Shrink wrapping (Option c)**: This is a packaging technique used for protection, branding, and preventing physical damage or contamination during transport; it is not a method for controlling biological diseases.
4. **Precooling (Option d)**: Precooling is the rapid removal of field heat immediately after harvest. While it slows down the metabolic rate and the growth of pathogens (extending shelf life), it is a preservation technique rather than a specific 'control method' for eliminating existing diseases like HWT is.
In the context of NE India, Participatory Rural Appraisal (PRA) is particularly important because:
A)
Farmers prefer government-centric planning
B)
The region has diverse tribal knowledge and agro-ecological conditions
C)
Technology adoption is uniform across the region
D)
There is no need for local participation
Participatory Rural Appraisal (PRA) is a set of approaches and methods used to enable local people to share, enhance, and analyze their knowledge of their own life and conditions. In the context of North East (NE) India, PRA is critical for the following reasons: 1. Diversity: The region is characterized by a vast array of ethnic groups, each possessing unique indigenous technical knowledge (ITK) regarding farming and forest management. 2. Agro-ecological Variation: The terrain varies from plains to high mountains with diverse micro-climates, meaning a 'one-size-fits-all' government approach often fails. 3. Bottom-up Planning: PRA allows extension workers to integrate this local wisdom into scientific planning, ensuring that agricultural interventions are culturally acceptable and ecologically sustainable.
Why other options are incorrect:
- Option (a) is incorrect because PRA is designed specifically to move away from 'government-centric' (top-down) planning toward 'community-centric' (bottom-up) planning.
- Option (c) is incorrect because technology adoption is highly non-uniform due to differences in literacy, infrastructure, and traditional beliefs across different tribes and states.
- Option (d) is incorrect because local participation is the fundamental core of PRA; without it, the methodology does not exist.
Which of the following communication methods is most effective for women farmers in remote villages of Mizoram?
A)
Written reports and pamphlets
B)
Online webinars only
C)
Scientific journals
D)
Audio-visual aids and participatory demonstrations
In the context of agricultural extension, especially for marginalized or remote populations such as women farmers in rural Mizoram, the effectiveness of communication depends on accessibility, literacy levels, and cultural relevance.
1. **Why Option (d) is correct**: Audio-visual aids (videos, posters, radio) and participatory demonstrations (Method Demonstrations or Result Demonstrations) are highly effective because they bypass literacy barriers and provide 'learning by doing.' For women farmers, who may have limited access to formal education or time constraints, seeing a technique applied in their own field (participatory) is the most persuasive and educational method.
2. **Why Option (a) is incorrect**: Written reports and pamphlets require a high level of literacy and can be ignored if the language is too technical or if the farmers cannot read.
3. **Why Option (b) is incorrect**: Online webinars require stable internet connectivity and digital literacy, both of which are often limited in 'remote villages' of hilly terrains like Mizoram.
4. **Why Option (c) is incorrect**: Scientific journals are academic documents intended for researchers and specialists, not for practical application by grassroots farmers.
A cybrid plant is formed when:
A)
Both nucleus and cytoplasm are fused
B)
Two haploid plants fuse naturally
C)
Only cytoplasm from one parent is combined with nucleus of another
D)
Mutation is induced by chemicals
A cybrid (cytoplasmic hybrid) is a plant produced by the fusion of the cytoplasm of one cell with the nucleus of another. This is typically achieved through somatic cell fusion (protoplast fusion) followed by the selective elimination or inactivation of one of the parental nuclei. The resulting plant contains the nuclear genome of one parent and the cytoplasmic organelles (like mitochondria and chloroplasts) of both parents, or specifically the cytoplasm of one parent combined with the nucleus of the other.
Analysis of options:
- Option (a) describes a standard somatic hybrid, where both nuclei and cytoplasms are fused.
- Option (b) describes sexual reproduction or specific breeding, not cybridization.
- Option (c) accurately describes the essence of a cybrid: the combination of a specific nucleus with a specific cytoplasm.
- Option (d) describes mutagenesis, which is a different process from hybridization or cybridization.
Break-even analysis in farm management is used to:
A)
Determine crop yield only
B)
Identify the level of production where total cost equals total revenue
C)
Calculate soil fertility
D)
Estimate labour requirement
Break-even analysis is a fundamental tool in farm management and economics used to determine the 'Break-Even Point' (BEP). The BEP is the specific volume of production or sales at which the total revenue generated from the farm enterprise exactly equals the total costs (both fixed and variable) incurred. At this point, the farm makes zero profit and zero loss.
Reasoning for other options:
- Option (a) is incorrect because crop yield is a physical measurement of production, not a financial analysis of costs and revenues.
- Option (c) is incorrect because soil fertility is a biological/chemical property of the land, measured through soil testing, not financial analysis.
- Option (d) is incorrect because labour requirement is part of resource planning and budgeting, whereas break-even analysis focuses on the financial viability of the production level.
One of the major challenges in implementing the T&V (Training and Visit) system in hill regions of NE India is:
A)
Lack of proven technologies
B)
Difficult terrain and dispersed villages
C)
Farmers unwillingness to learn
D)
Excessive financial resources
The Training and Visit (T&V) system, developed by Daniel Benor, relies on a rigid, highly structured schedule of visits by Village Extension Workers (VEWs) to contact farmers on a fixed rotation. In the hill regions of Northeast (NE) India, the geographical landscape is characterized by rugged terrain, steep slopes, and villages that are widely dispersed and often isolated. This makes the strict adherence to a fixed visit schedule physically and logistically nearly impossible, as travel time between dispersed villages is high and accessibility is often hindered by weather and infrastructure.
Why other options are incorrect:
- (a) Lack of proven technologies: While site-specific technology is always needed, the primary 'implementation' challenge of the T&V system is logistical, not a lack of science.
- (c) Farmers unwillingness to learn: Farmers in NE India are generally receptive to productivity improvements; the barrier is the delivery mechanism, not the willingness of the farmers.
- (d) Excessive financial resources: This is logically incorrect as the region typically faces resource constraints, and excessive funding would be an advantage, not a challenge.
Contract farming in horticulture primarily ensures:
A)
Fixed prices for inputs only
B)
Elimination of all production risks
C)
Free labour supply
D)
Guaranteed market and price for farm produce
Contract farming is an agreement between farmers and buyers (such as agribusiness firms or processors) where the buyer agrees to purchase a specific quantity of a crop at a pre-determined price.
1. Why Option (d) is correct: The primary objective of contract farming in horticulture (which involves perishable crops like fruits and vegetables) is to reduce market risk. By fixing the price and quantity beforehand, the farmer is guaranteed a buyer (market) and a specific price, protecting them from the volatility of market price fluctuations.
2. Why Option (a) is incorrect: While contracts may specify input quality or provide inputs, they do not primarily exist to fix the price of inputs alone; the core value is the output agreement.
3. Why Option (b) is incorrect: Contract farming reduces 'market risk' (price and sale), but it cannot eliminate 'production risks' such as pests, diseases, or natural calamities (weather), unless specific insurance clauses are added, which is not the primary definition of the system.
4. Why Option (c) is incorrect: Labour supply is not 'free' in contract farming; farmers still bear the cost of labour or are paid for it, depending on the specific contract terms.
Bt cotton is genetically engineered to:
A)
Resist herbicides
B)
Produce an insecticidal protein from Bacillus thuringiensis
C)
Tolerate drought conditions
D)
Increase seed oil content
Bt cotton is a genetically modified crop created by inserting a specific gene from the soil bacterium 'Bacillus thuringiensis' (Bt) into the cotton genome. This gene encodes for Cry proteins (crystal proteins), which are endotoxins. When target pests, such as the bollworm, ingest the plant tissue, the protein is activated in the alkaline environment of the insect's midgut, leading to pore formation in the gut wall and eventual death of the insect.
Analysis of other options:
- Option (a): Herbicide resistance is a characteristic of 'Roundup Ready' crops (e.g., using the cp4 epsps gene), not the primary purpose of Bt technology.
- Option (c): Drought tolerance involves different genetic modifications (e.g., manipulating osmotic stress genes), which is not the function of the Bt gene.
- Option (d): Increasing seed oil content involves metabolic engineering of lipid biosynthesis pathways, unrelated to the insecticidal properties of Bacillus thuringiensis.
Which of the following surface coating material for fruits & vegetables is obtained from shells of crustaceans like crabs, shrimps, etc?
A)
Chitosan
B)
Carnauba wax
C)
Shellac
D)
Alginates
Step-by-step reasoning: 1. The question asks for a surface coating material derived from the shells of crustaceans (crabs, shrimps, etc.). 2. Chitosan is a linear polysaccharide derived from chitin, which is the primary structural component in the exoskeletons of arthropods, including the shells of crustaceans. It is widely used in post-harvest technology as an edible coating due to its antimicrobial and antifungal properties. 3. Carnauba wax is obtained from the leaves of the Carnauba palm (Copernicia prunifera). 4. Shellac is a resin secreted by the female lac bug (Kerria lacca). 5. Alginates are polysaccharides derived from brown seaweed (algae). Therefore, only Chitosan fits the description of being derived from crustacean shells.
Which of the following is the primary purpose of anther culture in plant tissue culture?
A)
To induce somatic embryogenesis
B)
To produce haploid plants for breeding purposes
C)
To regenerate plants from leaf explants
D)
To study the effects of mutagens on plant cells
Anther culture is a specialized plant tissue culture technique where anthers (the pollen-bearing part of the stamen) are used as explants. Since pollen grains are the products of meiosis, they are haploid (containing only one set of chromosomes). By inducing these haploid cells to develop into plants, researchers can create haploid plants. These are extremely valuable in plant breeding because they allow for the rapid production of homozygous lines (through chromosome doubling using agents like colchicine), which would otherwise take several generations of self-pollination to achieve.
Why other options are incorrect:
- Option (a): While somatic embryogenesis can occur in various tissues, the specific goal of anther culture is to utilize the gametic (haploid) nature of the cells, not just any somatic embryogenesis.
- Option (c): Regenerating plants from leaf explants is known as organogenesis or somatic embryogenesis from vegetative tissue, not anther culture.
- Option (d): While mutagens can be applied to any tissue culture, the primary purpose of choosing anthers specifically is to obtain haploids, not to study mutagenesis.
Buttoning is a physiological disorder in:
A)
Garlic
B)
Onion
C)
Radish
D)
Cauliflower
Buttoning is a physiological disorder specifically associated with onion (Allium cepa) cultivation. It occurs when the onion bulb fails to swell and remains small, resembling a button. This disorder is typically caused by environmental stressors such as low temperatures during the bulb formation stage, nitrogen deficiency, or poor quality of planting sets. In contrast, garlic (a) does not typically exhibit this specific named disorder; radish (c) is more prone to disorders like pithiness or hollow heart; and cauliflower (d) is known for disorders like whipping or riceiness. Therefore, buttoning is a characteristic physiological issue in onions.