UPSC Mains Answer PYQ 2023: Agriculture Paper 2 (Section- A) | Agriculture Optional Notes for UPSC PDF Download

Section - A

Q1: Answer the following questions in about 150 words each :    (10x5=50)
(a) Enumerate the functions of Endoplasmic reticulum and Golgi apparatus.    (10 Marks)
Ans: 
Introduction: 
The endoplasmic reticulum (ER) and Golgi apparatus are essential cellular organelles involved in the synthesis, modification, and transport of proteins and lipids.

Endoplasmic Reticulum (ER):

• Protein Synthesis: The rough ER, studded with ribosomes, is responsible for synthesizing proteins that are destined for secretion or insertion into membranes.

• Lipid Synthesis: The smooth ER is involved in the synthesis of lipids, including phospholipids and cholesterol.

• Protein Folding and Modification: The ER provides a controlled environment for proper folding and post-translational modifications of proteins.

• Detoxification: The smooth ER in liver cells detoxifies drugs and harmful substances by metabolizing them into water-soluble forms.

• Calcium Storage: The ER stores and regulates calcium ion levels, which are crucial for various cellular processes.

Golgi Apparatus:

• Protein Modification and Sorting: The Golgi apparatus receives proteins from the ER and modifies them by adding sugars or other groups. It also sorts and packages proteins into vesicles for transport.

• Lipid Metabolism: It plays a role in lipid metabolism, modifying and sorting lipids for cellular use or export.

• Formation of Lysosomes: The Golgi apparatus synthesizes lysosomal enzymes and packages them into vesicles called lysosomes.

• Cell Wall Formation (in plant cells): In plant cells, the Golgi apparatus is involved in synthesizing components of the cell wall, such as cellulose.

• Secretion of Cellulose in Some Protists: In certain protists, the Golgi apparatus secretes cellulose, which forms protective coverings.

Conclusion: 
The endoplasmic reticulum and Golgi apparatus work in tandem to ensure proper synthesis, modification, and transport of proteins and lipids within the cell, playing critical roles in cellular function.

(b) Explain inbreeding depression and its effect in crops. Also explain the degrees of inbreeding depression.    (10 Marks)
Ans: 
Introduction:
Inbreeding depression occurs when closely related individuals are bred together over several generations, leading to a decline in the fitness and productivity of the offspring.

Effects of Inbreeding Depression:

• Reduced Vigor and Growth: Offspring of closely related parents may exhibit slower growth rates and reduced overall vigor.

• Increased Susceptibility to Diseases: Weakened immune systems and genetic vulnerabilities make inbred plants more susceptible to diseases and pests.

• Decreased Reproductive Success: Inbred plants may produce fewer viable seeds or have lower pollen viability, reducing reproductive success.

• Loss of Heterozygosity: Inbreeding leads to the loss of genetic diversity, as offspring become increasingly homozygous for deleterious alleles.

Degrees of Inbreeding Depression:

• First-Degree Inbreeding: Offspring result from the mating of siblings or parent-offspring pairs. This leads to the highest risk of inbreeding depression.

• Second-Degree Inbreeding: Offspring result from the mating of first cousins. The risk of inbreeding depression is lower compared to first-degree inbreeding.

• Third-Degree Inbreeding and Beyond: As the degree of relatedness decreases, so does the risk of inbreeding depression. However, some level of risk remains.

Example: Inbreeding depression can be observed in self-pollinating crops like wheat. Continuous self-pollination over generations can lead to reduced yields and poor plant health due to accumulated genetic defects.

Conclusion: 
Managing inbreeding is crucial in crop breeding programs to maintain genetic diversity and prevent the negative effects of inbreeding depression.

(c) Briefly discuss the requirements for production of certified seeds.    (10 Marks)
Ans:
Introduction:
Certified seeds are high-quality seeds that meet specific standards of purity, germination, and genetic identity. Their production involves several key requirements.

Requirements:

• Genetic Purity: Certified seeds must possess genetic purity, meaning they should be true-to-type and free from genetic contamination.

• Physical Purity: Seeds should be free from impurities like other crop seeds, weed seeds, and inert matter.

• Germination Standards: Certified seeds must meet or exceed specified germination standards to ensure high and uniform germination rates.

• Field Inspection: Fields where certified seeds are produced must undergo regular inspections to ensure compliance with quality standards.

• Isolation Distance: Adequate isolation distances must be maintained to prevent cross-pollination with non-certified crops of the same species.

• Rogueing and Rouging: Removal of off-types and impurities from seed crops during the growing season.

Example: In the production of certified wheat seeds, farmers must maintain sufficient isolation distances from other wheat varieties to prevent cross-pollination. Field inspections are conducted to verify compliance with quality standards.

Conclusion: 
Production of certified seeds requires strict adherence to quality standards to ensure that the seeds are of high genetic and physical purity, promoting better crop performance and yield potential.

(d) Give the classification of soil water. Briefly discuss soil moisture availability with respect to soil type.    (10 Marks)
Ans: 
Introduction: 
Soil water is classified based on its availability to plants, which is crucial for determining irrigation and water management strategies.

Classification of Soil Water:

• Hygroscopic Water: Held tightly by soil particles and is not available for plant use. Plants cannot extract this water.

• Capillary Water: Held in soil capillaries and is available for plant uptake. This is the water that plants can access between field capacity and wilting point.

• Gravitational Water: Excess water that drains below the root zone due to gravity. It is not available for plant use.

Soil Moisture Availability with Respect to Soil Type:

• Sandy Soils: Have larger particles, allowing water to drain quickly. They have lower water-holding capacity and are prone to drought stress.

• Loam Soils: Have a balanced mixture of sand, silt, and clay particles. They retain moisture well and are considered ideal for most crops.

• Clay Soils: Have fine particles that hold water tightly. They have high water-holding capacity but can be prone to waterlogging.

Example: In a sandy soil, water drains rapidly, making it necessary to irrigate more frequently. In contrast, a loam soil retains moisture effectively, requiring less frequent irrigation.

Conclusion: 
Understanding soil water classification and moisture availability based on soil type is crucial for making informed decisions regarding irrigation, crop selection, and water management practices.

(e) Write down about the origin and domestication of rice.    (10 Marks)
Ans: 
Introduction: 
Rice (Oryza sativa) is one of the world's most important staple crops, providing a significant portion of global food consumption. Its origin and domestication have a rich history.

Origin:

• Rice is believed to have originated in the region spanning from the eastern Himalayas to northern India, and possibly parts of Thailand and Myanmar.

Domestication:

• Over thousands of years, wild rice varieties were gradually selected and cultivated by early agricultural communities.

Example of Domestication:

• The process of domestication involved selecting plants with desirable traits, such as larger grain size, non-shattering panicles (so seeds don't fall off easily), and improved taste.

Spread:

• From its origin, rice cultivation spread across Asia, reaching China around 2500 BC and eventually Japan and Korea.

Cultural Significance:

• Rice has deep cultural and economic significance in many Asian countries, shaping dietary habits, cultural practices, and economies.

Conclusion: 
The origin and domestication of rice represent a critical milestone in the history of agriculture. Its cultivation has had profound impacts on societies, economies, and cultures across Asia and beyond.

Q2:
(a) Enlist the molecular models of cell membrane and explain the models given by S.J. Singer and G. Nicholson (1972), Green and Capaldi (1974) and Racker (1976).     (20 Marks)
Ans: 
Introduction:
Cell membranes are dynamic structures composed of lipids and proteins. Several molecular models have been proposed to describe the organization of cell membranes.

S.J. Singer and G. Nicholson Model (1972):

• Fluid Mosaic Model:
  • Description: Describes the membrane as a dynamic, flexible structure with a mosaic of lipids and proteins.
  • Explanation: Lipids form a fluid bilayer with embedded proteins that can move laterally within the membrane.
  • Example: Phospholipids form the lipid bilayer, while integral and peripheral proteins are embedded within or attached to the membrane surface.

Green and Capaldi Model (1974):

• Layered Model:
  • Description: Proposes a layered structure with proteins sandwiched between lipid layers.
  • Explanation: Proteins are arranged in specific layers within the lipid bilayer, suggesting a more organized structure.
  • Example: This model emphasizes the ordered arrangement of proteins in the membrane.

Racker Model (1976):

• Proton Pump Hypothesis:
  • Description: Focuses on the role of membrane proteins in actively transporting protons.
  • Explanation: Membrane proteins, specifically ATPase, are involved in pumping protons across the membrane, generating a proton gradient.
  • Example: This model is significant in understanding energy transduction processes in cellular respiration.

Conclusion: 
These models have contributed to our understanding of cell membrane structure and function. While the Fluid Mosaic Model remains widely accepted, the other models have provided valuable insights into specific aspects of membrane organization.

(b) Give an account of seven different pairs of contrasting characters whose inheritance was studied by Mendel in Garden Pea (Pisum sativum). Give the reasons for Mendel’s success in the study.      (20 Marks)
Ans: 
Introduction: 
Gregor Mendel's experiments with garden peas laid the foundation for modern genetics. He studied seven pairs of contrasting characters in pea plants.

Contrasting Characters Studied by Mendel:

• Seed Color (Yellow vs. Green): Yellow (dominant) vs. green (recessive).

• Seed Texture (Smooth vs. Wrinkled): Smooth (dominant) vs. wrinkled (recessive).

• Flower Color (Purple vs. White): Purple (dominant) vs. white (recessive).

• Flower Position (Axial vs. Terminal): Axial (dominant) vs. terminal (recessive).

• Stem Length (Long vs. Short): Long (dominant) vs. short (recessive).

• Pod Color (Yellow vs. Green): Yellow (dominant) vs. green (recessive).

• Pod Shape (Inflated vs. Constricted): Inflated (dominant) vs. constricted (recessive).

Reasons for Mendel's Success:

• Selection of Suitable Organism: Pea plants (Pisum sativum) were ideal for Mendel's experiments due to their distinct traits, easy cultivation, and controlled pollination.

• Purity of Parental Lines: Mendel ensured that the plants used were true-breeding for specific traits, reducing variability in offspring.

• Large Sample Size: Mendel performed extensive experiments with thousands of plants, providing robust statistical data.

• Isolation of Crosses: Mendel performed controlled crosses, preventing unintended pollination from other plants.

• Mathematical Analysis: Mendel applied quantitative analysis to his data, introducing principles of probability and statistics.

Conclusion: 
Mendel's careful experimental design, selection of traits, and rigorous data analysis were instrumental in his groundbreaking discoveries in genetics.

(c) Explain various theories of inheritance. Write down the evidences suggesting the presence of cytoplasmic inheritance in the crosses’ results.      (10 Marks)
Ans: 
Introduction: 
Various theories have been proposed to explain the transmission of genetic traits. Cytoplasmic inheritance involves the transmission of genetic information through cytoplasmic organelles.

Theories of Inheritance:
1. Blending Inheritance:

• Description: Proposed that traits from parents blend in offspring, leading to uniform intermediate characteristics.
• Evidence Against: Doesn't explain how discrete traits reappear in later generations.

2. Particulate Inheritance (Mendelian Inheritance):

• Description: Genes are distinct units that maintain their integrity from generation to generation.
• Evidence For: Mendel's experiments with pea plants provided strong support for this theory.

3. Chromosomal Theory of Inheritance:

• Description: Genes are located on chromosomes, and their segregation and assortment during meiosis account for inheritance patterns.
• Evidence For: Observations of chromosome behavior during cell division.

Cytoplasmic Inheritance:

• Description: Involves the transmission of genetic information through cytoplasmic organelles like mitochondria and chloroplasts.
• Evidence:
  • Maternal inheritance of mitochondrial DNA in animals.
  • Presence of specific traits linked to cytoplasmic organelles (e.g., variegated leaf patterns due to chloroplast mutations).

Conclusion: 
While Mendelian inheritance primarily involves nuclear DNA, cytoplasmic inheritance plays a role in transmitting genetic information through organelles in the cytoplasm. This is particularly evident in traits linked to mitochondria and chloroplasts.

Q3:
(a) Describe the history of plant breeding in India. Write the objectives of plant breeding and methods for creation of variability for crop improvement.      (20 Marks)
Ans: 
Introduction: 
Plant breeding in India has a rich history dating back thousands of years. It has evolved from traditional practices to modern scientific methods.

Ancient and Traditional Practices (Pre-Independence):

• Selection and Cultivation of Desirable Traits: Ancient Indian farmers practiced mass selection, choosing plants with desirable traits for cultivation and seed saving.

• Crop Diversity and Indigenous Varieties: India is known for its diverse crop varieties, many of which were developed through generations of selection by farmers.

Post-Independence Era (1947 onwards):

• Formalization of Plant Breeding Programs: The Indian government established agricultural research institutes and universities, formalizing plant breeding efforts.

• Introduction of Green Revolution Varieties: High-yielding varieties of wheat and rice were introduced, leading to a significant increase in food production.

• Focus on Crop Improvement: Plant breeding programs targeted various crops like rice, wheat, millets, pulses, and oilseeds to improve yield, disease resistance, and other agronomic traits.

Recent Developments (21st Century):

• Emphasis on Biotechnology and Molecular Breeding: Adoption of biotechnological tools like genetic engineering, marker-assisted breeding, and genomics for accelerated crop improvement.

• Integration of Modern Techniques: Use of advanced technologies for trait introgression, hybrid development, and development of genetically modified (GM) crops.

Objectives of Plant Breeding:

• Improving Yield and Productivity: Developing varieties with higher yield potential to meet the increasing global demand for food.

• Enhancing Disease and Pest Resistance: Creating crops with genetic resistance to diseases and pests, reducing the reliance on chemical pesticides.

• Adapting to Environmental Stresses: Breeding for tolerance to abiotic stresses like drought, salinity, and temperature extremes.

Methods for Creation of Variability:

• Hybridization and Crossbreeding: Controlled pollination between different varieties or species to combine desirable traits.

• Mutation Breeding: Inducing mutations through radiation or chemicals to create genetic variability.

• Biotechnological Tools: Genetic engineering, CRISPR-Cas9 technology, and molecular markers for precise manipulation of genes.

Conclusion: 
The history of plant breeding in India showcases a transition from traditional practices to modern scientific methods, with a continued focus on improving crop varieties for food security and sustainability.

(b) Describe Systemic Acquired Resistance (SAR) and source of disease resistance with suitable examples. Write the advantages of breeding for disease resistance in plants.      (20 Marks)
Ans:
Introduction: 
SAR is a defense mechanism in plants that provides long-lasting protection against a broad spectrum of pathogens.

Systemic Acquired Resistance (SAR):

• Description: SAR is a type of induced resistance that occurs in plants following an initial attack by a pathogen.
• Mechanism: It involves the activation of defense pathways, leading to the production of secondary metabolites and enhanced expression of defense-related genes.
• Example: When a plant is infected by a pathogen, it produces signaling molecules like salicylic acid, triggering SAR. This prepares the entire plant for a potential subsequent attack.

Source of Disease Resistance:

• Natural Genetic Variation:

  • Some plant varieties possess inherent genetic resistance to specific pathogens.
  • Example: Certain wheat varieties have natural resistance to rust diseases.

• Breeding for Resistance:

  • Plant breeders select and develop varieties with improved disease resistance through controlled crosses and selection.
  • Example: Breeding for resistance to late blight in potatoes resulted in the development of varieties like Russet Burbank.

Advantages of Breeding for Disease Resistance:

• Reduction in Chemical Inputs: Resistant varieties require fewer chemical pesticides, reducing environmental impact and production costs.

• Sustainable Agriculture: Disease-resistant crops contribute to sustainable agriculture by reducing the reliance on chemical control measures.

• Improved Yield Stability: Resistant varieties are less susceptible to yield losses caused by disease outbreaks, providing more stable crop yields.

• Enhanced Food Security: Disease-resistant crops ensure a more reliable and consistent food supply, especially in regions prone to specific diseases.

Conclusion: 
Breeding for disease resistance in plants is a vital component of sustainable agriculture, contributing to reduced environmental impact, increased yield stability, and improved food security.

(c) What do you understand by graft incompatibility ? Describe the symptoms and causes of graft incompatibility in plants with suitable examples.      (10 Marks)
Ans: 
Introduction: 
Graft incompatibility is a condition where a graft union between two plant tissues fails to form a functional connection.

Symptoms of Graft Incompatibility:

• Limited Growth or Vigor: The grafted scion may exhibit stunted growth or reduced overall vigor compared to a compatible graft.

• Dieback or Wilt: The grafted scion may show symptoms of wilting, dieback of shoots, or general decline.

• Callus Formation: Instead of a well-integrated union, a callus may form at the graft site, indicating a lack of successful union.

Causes of Graft Incompatibility:

• Genetic Incompatibility: Differences in genetic makeup between the scion and rootstock can lead to incompatible grafts.

• Physiological Mismatch: Differences in water, nutrient, or hormonal requirements between scion and rootstock can hinder successful grafting.

• Disease or Pathogen Interaction: Presence of pathogens or diseases in one of the graft components can prevent successful union.

Examples of Graft Incompatibility:

• Apple and Pear Grafting: Grafting apple (Malus domestica) onto pear (Pyrus spp.) rootstock often results in incompatibility due to genetic differences.

• Citrus Grafting: Some citrus varieties exhibit incompatibility when grafted onto rootstocks of different species within the citrus genus.

Conclusion: 
Understanding graft compatibility is crucial in successful horticultural practices. Incompatible grafts can lead to poor growth, reduced yields, and plant decline, highlighting the importance of selecting compatible plant materials for grafting projects.

Q4:
(a) Discuss different forms of Intellectual Property Rights (IPR) in India.      (20 Marks)
Ans: 
Introduction: Intellectual Property Rights are legal rights granted to individuals or organizations for their creations or inventions. In India, various forms of IPR are recognized and protected.

Forms of IPR in India:
1. Patents:

• Definition: A patent grants exclusive rights to inventors for their inventions, preventing others from making, using, or selling the patented product or process.
• Example: An inventor of a new pharmaceutical compound can apply for a patent to protect their discovery.

2. Copyright:

• Definition: Copyright protects original works of authorship, including literary, musical, and artistic creations.
• Example: Authors, musicians, and artists have copyright protection for their books, songs, and artworks.

3. Trademarks:

• Definition: Trademarks are symbols, names, or logos used to identify and distinguish goods or services of one entity from others.
• Example: The logo of a well-known brand, like the Nike swoosh, is a trademark.

4. Designs:

• Definition: Design rights protect the visual design or ornamentation applied to an article.
• Example: The unique design of a smartphone or the pattern on a fabric can be protected.

5. Geographical Indications (GI):

• Definition: GI identifies a product as originating from a specific geographical location, with qualities, reputation, or characteristics associated with that place of origin.
• Example: Darjeeling tea and Basmati rice are examples of products protected under GI.

6. Plant Variety Protection (PVP):

• Definition: PVP grants breeders exclusive rights to market and sell a new plant variety for a certain period.
• Example: New varieties of crops developed through breeding programs can be protected under PVP.

Example: The Indian Patent Act of 1970 and subsequent amendments provide a framework for patent protection in India, ensuring inventors have the exclusive rights to their inventions for a specified period.

Conclusion: 
India's recognition and protection of various forms of IPR play a crucial role in fostering innovation, creativity, and economic development.

(b) Give an account of stomate anatomy and cytology. Write down the effect of light, water deficit, CO₂ concentration and temperature on stomatal movement along with the underlying mechanism.      (20 Marks)
Ans: 
Introduction:
Stomata are specialized pores on the surface of leaves that facilitate gas exchange. They consist of guard cells that regulate their opening and closing.

Stomatal Anatomy and Cytology:
1. Guard Cells:

• Structure: Bean-shaped cells surrounding the stomatal pore.
• Cytology: Contain chloroplasts, nucleus, and various organelles.

2. Stomatal Pore:

• Structure: Opening between two guard cells.
• Function: Allows for the exchange of gases (CO₂, O₂, and water vapor) between the plant and the atmosphere.

Factors Affecting Stomatal Movement:
1. Light:

• Effect: Light stimulates stomatal opening through photosynthesis, allowing plants to take in CO₂.
• Mechanism: Light activates proton pumps in guard cells, leading to K⁺ influx and water uptake, causing turgor pressure increase and stomatal opening.

2. Water Deficit (Drought Stress):

• Effect: Water deficit leads to stomatal closure to reduce water loss through transpiration.
• Mechanism: Abscisic acid (ABA) is produced in response to water stress, promoting K⁺ efflux and water loss from guard cells, leading to stomatal closure.

3. CO₂ Concentration:

• Effect: High levels of CO₂ promote stomatal closure to conserve water.
• Mechanism: Elevated CO₂ inhibits stomatal opening by reducing the sensitivity of guard cells to environmental stimuli.

4. Temperature:

• Effect: High temperatures can lead to stomatal closure to prevent excessive water loss.
• Mechanism: High temperatures activate ABA production, leading to stomatal closure.

Example: In a hot, dry environment, a plant will close its stomata to conserve water. This prevents excessive transpiration and helps the plant survive water stress.

Conclusion:
Understanding the factors influencing stomatal movement is crucial in agricultural and ecological contexts, as it directly impacts a plant's water-use efficiency and overall survival.

(c) Describe the role of State Seed Certification Agencies.      (10 Marks)
Ans: 
Introduction: 
State Seed Certification Agencies play a vital role in ensuring the quality of seeds available to farmers, thereby enhancing agricultural productivity.

Functions of State Seed Certification Agencies:

• Seed Testing and Quality Control: Conduct germination tests, purity tests, and other quality assessments to ensure seeds meet specified standards.

• Certification of Seeds: Grant certification to seed lots that meet quality and genetic purity criteria, indicating they are suitable for planting.

• Labeling and Tagging: Ensure that seed packages are properly labeled with essential information, including germination percentage, purity, and other details.

• Field Inspection: Conduct inspections of seed production fields to verify adherence to isolation distances and other quality standards.

• Varietal Purity Verification: Verify that seeds of registered varieties maintain their genetic purity through field inspections and laboratory tests.

Example: If a farmer purchases certified seeds for a specific crop, they can be assured that the seeds have undergone rigorous testing and meet quality standards, increasing the likelihood of a successful and productive crop.

Conclusion:
State Seed Certification Agencies play a critical role in maintaining the integrity and quality of seeds available to farmers, contributing to improved agricultural productivity and food security.