#agriculture

BOTANY

Which of the following microbes is commonly used for the biological control of soil-borne fungal pathogens?

Trichoderma is a fungus that acts as a biocontrol agent against soil-borne fungal pathogens. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Botany section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Botany portion (Latest NCERT Textbooks for Academic Session 2026-27 -

View Details

BOTANY

Which plant hormone is used commercially for fruit ripening?

Ethylene is widely used for the artificial ripening of fruits such as bananas and tomatoes. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.

View Details

Transgenic Plant -1

Which strategy delays insect resistance development?

Resistance evolution to Bt toxins accelerated when transgenic crops grown continuously on large acreage without alternative hosts for susceptible insects. Homozygous resistant insects emerging from Bt fields mating with each other rapidly increase resistance allele frequency. Refuge strategy maintains pool of susceptible individuals by planting non-transgenic crop nearby or mixing seeds. Susceptible moths from refuge mate with rare resistant survivors from Bt field producing heterozygous offspring. High dose of toxin expressed in transgenic plants kills heterozygotes because resistance generally recessive, diluting resistant alleles and delaying fixation. EPA mandates 20 percent structured refuge for cotton and 5 to 20 percent for corn depending on region. Data from Arizona pink bollworm program shows refuge compliance helped preserve Bt efficacy for over decade. Planting pattern may include block refuge, strip refuge, or seed mix. Hence mixing GM and non-GM crops implements high-dose refuge principle, primary tactic delaying insect resistance development to Cry toxins in commercial agriculture. Implementation details include 20 percent structured refuge for cotton and 5 to 20 percent for corn, planted within 0.5 mile of Bt field to ensure random mating. Monitoring of resistance allele frequency by F2 screen detects early resistance evolution allowing proactive management including increased refuge

Ref: Gould Annu Rev Entomol 1998 refuge strategy; Tabashnik Annu Rev Entomol 2013 mixing; NCBI NBK131103 insect resistance management; EPA refuge guidance 2001.

View Details

Transgenic Plant -1

Worldwide maximum cultivated transgenic crop is:

International Service for Acquisition of Agri-biotech Applications annually reports global adoption of GM crops. Historical data from 1996 to 2023 demonstrates herbicide tolerance trait dominates both by trait type and crop species. Among crops, soybean engineered for glyphosate tolerance occupied largest area, reaching over 94 million hectares in 2019, accounting for about half of all GM hectarage. Drivers include high demand for protein meal for animal feed, suitability of herbicide tolerance for large-scale mechanized farming in United States, Brazil, Argentina, adoption of no-till practices conserving soil moisture. Bt cotton occupies second but substantially less area. Edible vaccines and Golden rice remain uncommercialized or limited. Economic analysis shows herbicide tolerant soybean reduced production costs and simplified weed management compared to conventional. Therefore statistical surveys consistently identify herbicide resistant soybean as most widely cultivated transgenic crop worldwide, illustrating market preference for input trait providing management convenience over output traits requiring consumer acceptance. Adoption data illustrates correlation between herbicide tolerance trait and conservation tillage practices reducing soil erosion and carbon emissions. Continued dominance of soybean indicates farmer preference for simplified weed management enabling timely planting over high-value specialty traits requiring niche markets and identity preservation systems.

Ref: ISAAA Brief 55 2019 global status herbicide tolerant soybean dominant; James ISAAA 2014; NCBI NBK131103 statistics; https://www.isaaa.org/resources/publications/briefs/55/

View Details

Transgenic Plant -1

Bollgard II cotton expresses which genes?

Bollgard II represents stacked trait strategy designed to delay resistance and broaden insecticidal spectrum. First generation Bollgard expressing only Cry1Ac selected resistance alleles in Helicoverpa armigera under continuous exposure. Incorporating second toxin Cry2Ab with different binding site, recognizing distinct aminopeptidase N and ABC transporter, requires insects to carry simultaneous mutations in two receptors to survive, probability drastically lower. Both genes driven by enhanced constitutive promoters provide high dose exceeding LD99 for heterozygous susceptible larvae. Expression occurs in squares, bolls, and leaves protecting whole season. Commercial cultivation since 2003 showed reduced insecticide applications, preservation of beneficial predators, and improved yield. Stacking Cry1Ac plus Cry2Ab exemplifies gene pyramiding concept central to insect resistance management guidelines mandated by EPA for transgenic cotton deployment and maintenance of technology durability against lepidopteran pests. Molecular analysis shows Cry1Ac expression 2 to 5 micrograms per gram fresh weight in leaves, Cry2Ab slightly lower but additive. Insect bioassays with Helicoverpa zea second instar larvae fed on Bollgard II leaves cause complete mortality within 5 days compared to 50 percent mortality on single toxin line. Adoption data indicates reduced insecticide load and improved environmental impact quotient. Therefore combination Cry1Ac plus Cry2Ab exemplifies successful gene stacking delaying resistance

Ref: ISAAA Brief 43 Bollgard II; Tabashnik Nat Biotechnol 2009 pyramiding; NCBI NBK24601 Cry1Ac Cry2Ab; https://www.isaaa.org/resources/publications/briefs/43/

View Details

Plant Breeding 1

Strict quarantine laws are aimed at preventing:

Quarantine statutes aim primarily at exclusion of exotic pests, pathogens and weeds not present in importing country, preventing establishment of new epidemics that could devastate agriculture and trade. Under Plant Quarantine Regulation Order 2003 enforced by NBPGR, every consignment requires phytosanitary certificate from source nation, inspection upon arrival for insects such as shot hole borer Xyleborus ferrugineus, fungi such as Dothidella ulei causing South American leaf blight, and weed seeds. Provisions include post-entry quarantine growing for one vegetative season, treatment with systemic fungicides and destruction of infected lots. Compliance preserves biodiversity, safeguards national food security and maintains compliance with IPPC international trade obligations, avoiding costly eradication programs and embargoes. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs. Additional insights from genomic studies reveal QTL clusters, epigenetic modifications and protein interactions that influence trait expression under varied agro-climatic conditions and management.

Ref: Plant Quarantine Order 2003 Indiankanoon; IPPC ISPM 2 Pest Risk Analysis; e-coursesonline quarantine prevention objective.

View Details

Plant Breeding 1

Lantana camara and water hyacinth are examples of:

Lantana camara native to Central and South America introduced into India in 1809 as ornamental shrub for its multicolored corymbs and year-round flowering. Eichhornia similarly introduced as aquatic ornamental. Both escaped cultivation demonstrating characteristics listed by Baker as ideal weeds: rapid asexual proliferation via suckers and stolons, high seed output exceeding 10,000 per plant, dormancy, tolerance to drought and waterlogging, and production of allelopathic secondary metabolites lantadenes and phenolics inhibiting germination of neighboring crops. Dense thickets reduce pasture carrying capacity, harbor disease vectors and increase fire hazard. Biological control attempts using Octotoma championi leaf miner for Lantana and Neochetina weevils for water hyacinth illustrate management challenges, highlighting lesson for careful risk assessment during ornamental introduction. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: FAO Invasive Weed Management Lantana; CABI Datasheet Eichhornia and Lantana; BSI Invasive alien plants India.

View Details

Plant Breeding 1

Which of the following is a demerit of plant introduction?

Despite expanding gene pools, introduction carries inadvertent adverse consequences representing demerits. Along with desired cultivars, weed seeds such as Phalaris minor, Avena fatua, Parthenium hysterophorus introduced with PL-480 wheat shipments from USA in 1960s became dominant weeds competing for light, nutrients and space, producing allelochemicals like parthenin suppressing crop growth. Pathogens such as coffee rust, potato late blight and diseases like downy mildew also hitchhike as dormant mycelium. Invasive ornamentals outcompete native flora reducing biodiversity index. Economic costs escalate due to increased herbicide use, mechanical weeding and yield losses estimated in billions. Hence strict sampling, seed cleaning, and certification protocols mandatory to minimize ecological disruption accompanying germplasm exchange programs. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs. Additional insights from genomic studies reveal QTL clusters, epigenetic modifications and protein interactions that influence trait expression under varied agro-climatic conditions and management.

Ref: Kohli RK Invasive Alien Species India; NCERT Class XII Biodiversity demerits; CABI Invasive weed Parthenium origin.

View Details

Plant Breeding 1

Improvement of performance of introduced varieties over generations is called:

Acclimatization describes gradual adaptive improvement in performance of introduced variety over successive generations grown in new environment. Initially introduced genotype may flower late, show asynchronous maturity or susceptibility to local leaf rust races. Continuous natural and farmer selection favours individuals with favorable alleles for photoperiod insensitivity, thermal tolerance, efficient nutrient uptake and pathogen defense mediated by polygenic QTL. Epigenetic modifications such as DNA methylation changes altering gene expression without sequence change also contribute. Over time mean yield, harvest index and stability increase as allele frequencies shift toward local optimum. Unlike heterosis which is immediate, acclimatization involves progressive narrowing of genotype x environment interaction variance, exemplified by Mexican wheat adapting to Indo-Gangetic plains after several cycles of selection for earliness. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: Allard RW Principles Plant Breeding Acclimatization chapter; e-courses Breeding Fruit Crops Acclimatization; FAO Adaptation.

View Details

Plant Breeding 1

Assignment of entry numbers during plant introduction is called:

Cataloging systematizes documentation by assigning unique accession numbers to each introduced sample clearing quarantine. NBPGR uses EC prefix for exotic collections from abroad, IC for indigenous germplasm within India, IW for wild relatives and ET for transgenics. Passport information including scientific name, cultivar name, pedigree, country of origin, donor organization, collection site coordinates, morphological descriptors and quarantine clearance date entered into Genebank Information System. This accessioning prevents naming confusion, enables retrieval via searchable database, links physical storage location in medium-term module at 4C or long-term at -20C, and supports benefit-sharing under PGR regulations. Proper cataloging precedes agronomic evaluation, ensuring traceability across multi-location testing and compliance with international descriptor standards from Bioversity International. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: NBPGR Genebank Manual Accessioning; Bioversity Descriptors; Singh BD Plant Breeding Cataloguing step.

View Details

Plant Breeding 1

The main purpose of quarantine in plant introduction is to:

Quarantine imposes enforced isolation and testing to intercept exotic pathogens, nematodes, insects and weed seeds hidden in imported seeds, tubers or cuttings. Legal basis includes Destructive Insects and Pests Act 1914 and Plant Quarantine Order 2003 requiring inspection at seaports, airports and land customs. NBPGR National Quarantine Laboratory performs visual inspection, X-ray for insect damage, blotter test for fungi like Tilletia and Fusarium, washing test for seeds, and serological ELISA and PCR for viruses such as banana bunchy top and potato latent viruses. Suspect samples undergo fumigation with aluminum phosphide, hot water treatment at 52C, or pesticide dip before clearance. Effective quarantine prevented entry of devastating pathogens and preserves ecosystem equilibrium and export credibility of Indian agricultural produce. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: IPPC ISPM Standards; Plant Quarantine Order 2003; e-coursesonline.iasri.res.in Plant Quarantine chapter; NBPGR Quarantine.

View Details

Plant Breeding 1

Which is the first step in plant introduction?

Procurement initiates introduction by identifying, requesting and acquiring desired germplasm along with passport data. Breeder formulates objective for traits like drought tolerance, nutritional quality or disease resistance and submits proforma to NBPGR Plant Exchange Division citing botanical name, gene pool and donor institute. NBPGR consults databases, issues import permit, negotiates Material Transfer Agreement and compliance with Convention on Biological Diversity. Alternatively explorers collect wild relatives, landraces or elite lines during targeted expeditions, preserving herbarium voucher, latitude, altitude and farmer knowledge. Propagules accompanied by phytosanitary certificate confirming freedom from quarantine pests. Without rigorous procurement, duplicate accessions accumulate, narrow diversity captured and risk of contaminated seed lots increases, delaying subsequent quarantine and evaluation stages. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: NBPGR Manual Plant Exchange and Procurement; FAO Genebank Standards; DDUGU Notes Domestication Introduction Procurement.

View Details