Scientific Officer-Agronomy-Practice-8

Prepare for the SPSC Scientific Officer Agronomy examination with 20 practice MCQs and explanations on plant breeding, experimental design, soil properties, crop physiology, seed testing, nutrient management, and weed resistance.

Practice questions

  1. In plant breeding, heterosis refers to:
    • Loss of seed viability during storage
    • Reduced growth caused by waterlogging
    • Superior performance of a hybrid compared with its parents for one or more traits
    • Complete absence of genetic variation
  2. Which breeding method is commonly used to transfer a specific desirable gene into an established variety while retaining most of its other characteristics?
    • Backcross breeding
    • Mass harvesting
    • Continuous flooding
    • Random field sampling
  3. In plant breeding, heritability estimates the proportion of observed phenotypic variation attributable to genetic variation within a particular population and environment. Which term describes this concept?
    • Transpiration
    • Germination
    • Crop coefficient
    • Heritability
  4. Which instrument is commonly used to measure soil strength or resistance to penetration in the field?
    • Hygrometer
    • Soil penetrometer
    • Spectrophotometer
    • Rain gauge
  5. Which of the following is a major function of boron in many crop plants?
    • Serving as the central atom in chlorophyll
    • Replacing carbon as the main structural element
    • Supporting cell-wall formation and reproductive development
    • Acting as the main source of plant energy
  6. In a randomized complete block design, the main purpose of forming blocks is to:
    • Account for known variation among experimental units within the field
    • Eliminate the need for randomization
    • Ensure that every treatment produces the same yield
    • Replace replication with a single observation
  7. Which term describes the percentage of a harvested crop's biological yield represented by its economic yield?
    • Germination percentage
    • Leaf area index
    • Harvest duration
    • Harvest index
  8. In crop production, the leaf area index (LAI) is defined as:
    • Root length divided by plant height
    • Leaf area per unit of ground area
    • Grain weight divided by seed weight
    • Number of flowers per root system
  9. Which method is most appropriate for estimating crop evapotranspiration using reference evapotranspiration and a crop coefficient?
    • Multiply reference evapotranspiration by the crop coefficient
    • Add seed rate to soil pH
    • Divide plant population by harvest index
    • Subtract fertilizer rate from rainfall
  10. Which process converts ammonium into nitrite and then nitrate under suitable aerobic soil conditions?
    • Denitrification
    • Nitrogen fixation
    • Nitrification
    • Ammonification
  11. Which soil property is represented by the mass of oven-dry soil per unit of its total volume, including pore spaces?
    • Particle density
    • Bulk density
    • Soil pH
    • Electrical conductivity
  12. Which term describes the ability of a soil to supply essential nutrients to plants in suitable amounts and proportions?
    • Soil colour
    • Soil temperature alone
    • Soil slope
    • Soil fertility
  13. In plant disease management, crop sanitation primarily involves:
    • Removing or managing infected plant material and other sources of inoculum
    • Increasing irrigation regardless of crop need
    • Applying nitrogen without soil or crop assessment
    • Planting the same susceptible crop continuously
  14. Which statement best describes biological control of agricultural pests?
    • Using only mechanical ploughing to remove weeds
    • Increasing pest populations to protect crops
    • Using natural enemies or other biological agents to suppress pest populations
    • Applying every available pesticide at the same time
  15. In a seed germination test, germination percentage is generally calculated from:
    • The number of empty seed bags in storage
    • The number of seeds that meet the test's germination criteria divided by the total number tested, multiplied by 100
    • The mass of fertilizer applied to the field
    • The total length of all field boundaries
  16. Which of the following is a primary purpose of maintaining genetic purity in a seed-production programme?
    • Increasing the soil's electrical conductivity
    • Making all varieties genetically identical
    • Removing the need for seed testing
    • Preserving the identity and varietal characteristics of the intended crop variety
  17. Which practice helps reduce nutrient losses caused by runoff and leaching when fertilizer is applied?
    • Matching fertilizer rate, timing, placement, and source to crop needs and field conditions
    • Applying every nutrient at the maximum possible rate
    • Applying all fertilizer immediately before heavy rainfall
    • Ignoring soil-test results and crop growth stage
  18. Which process describes the loss of nitrogen from nitrate through microbial reduction to gaseous nitrogen forms under suitable conditions?
    • Nitrification
    • Mineral weathering
    • Denitrification
    • Photosynthesis
  19. What is the main purpose of a control treatment in a field experiment?
    • To ensure that every treatment receives an identical result
    • To provide a comparison for evaluating the effects of experimental treatments
    • To eliminate the need to record observations
    • To guarantee that experimental error is zero
  20. Which practice is most appropriate for managing a herbicide-resistant weed population?
    • Repeatedly applying the same herbicide mode of action alone
    • Increasing the application rate beyond label directions
    • Treating weeds without identifying the species or resistance risk
    • Combining appropriate cultural, mechanical, and chemical tactics while following resistance-management guidance
MM Academy Preparing your learning space…