Scientific Officer-Plant Breeding-Practice-7

Practice questions

1. What does mid-parent heterosis measure in hybrid breeding?
   • Superiority of a hybrid over the average performance of its two parents
   • Superiority of a parent over its own previous generation
   • Difference between two unrelated varieties in seed colour
   • Reduction in hybrid performance below both parents
2. What is heterobeltiosis?
   • Hybrid superiority over the better-performing parent
   • Hybrid superiority over the average of all varieties
   • Reduction in performance compared with the poorer parent
   • Similarity between the two parental genotypes
3. What is standard heterosis in hybrid evaluation?
   • Superiority of a hybrid over an established commercial check variety
   • Superiority of a hybrid over the average of its parents
   • Difference between the two parental lines
   • Variation among plants within one parental line
4. What is the main purpose of detasseling in hybrid maize seed production?
   • Removing tassels from female parent plants to prevent self-pollination
   • Removing ears from male parent plants before flowering
   • Preventing the germination of maize pollen
   • Increasing the chromosome number of female plants
5. Why is isolation distance maintained between seed production fields of different varieties?
   • To reduce unwanted cross-pollination and genetic contamination
   • To increase soil temperature during flowering
   • To prevent all insect activity in the field
   • To improve seed size through wider plant spacing
6. What is rouging in seed production?
   • Removing off-type and diseased plants from a seed crop
   • Mixing seed lots from different varieties
   • Applying additional fertiliser before harvesting
   • Separating seed according to its moisture content
7. Which seed class is generally produced directly from breeder seed in a standard seed multiplication chain?
   • Foundation seed
   • Certified seed
   • Truthfully labelled seed
   • Commercial grain
8. What is the primary purpose of field inspection during seed certification?
   • Checking varietal identity, field standards and seed crop quality requirements
   • Measuring the market price of harvested grain
   • Determining the nutritional value of the final crop
   • Estimating the rainfall received by neighbouring farms
9. Which three characteristics are assessed in DUS testing of a plant variety?
   • Distinctness, uniformity and stability
   • Density, usefulness and size
   • Drought tolerance, uniformity and soil fertility
   • Dormancy, uptake and storage
10. What does VCU testing evaluate in a candidate crop variety?
    • Its value for cultivation and use under relevant growing conditions
    • Its chromosome number alone
    • Its seed colour without field evaluation
    • Its genetic similarity to every existing variety
11. Which statement best distinguishes seed vigour from standard germination percentage?
    • Vigour concerns seed performance under a range of conditions, including stress
    • Vigour measures only the physical weight of individual seeds
    • Germination percentage measures only seed colour
    • Vigour and germination percentage are always identical measurements
12. What is the main purpose of an accelerated ageing test in seed science?
    • Assessing seed vigour by exposing seeds to elevated temperature and humidity
    • Determining the genetic identity of a crop variety
    • Measuring the protein content of mature leaves
    • Increasing seed longevity through controlled drying
13. What is the primary objective of seed health testing?
    • Detecting seed-associated pathogens and other harmful organisms
    • Measuring the height of mature crop plants
    • Determining the number of chromosomes in pollen grains
    • Estimating the market value of harvested seed
14. What is the purpose of a seed purity analysis?
    • Determining the proportion of pure seed and other physical components in a seed lot
    • Measuring the genetic distance between two parent lines
    • Calculating the heritability of grain yield
    • Determining the flowering time of a variety
15. What is genetic erosion in crop plants?
    • Loss of genetic diversity within crop species and their related populations
    • Increase in the number of available crop varieties
    • Improvement in the uniformity of a certified seed lot
    • Development of new alleles through controlled crossing
16. What is a core collection in plant genetic resource management?
    • A smaller representative subset of a larger germplasm collection
    • A collection containing only one genotype
    • A seed lot consisting exclusively of commercial hybrids
    • A collection of plants selected only for maximum height
17. What is pre-breeding in crop improvement?
    • Identifying and transferring useful genetic variation from unadapted or exotic materials into material usable by breeders
    • Producing certified seed for immediate commercial sale
    • Replacing all conventional breeding with fertiliser application
    • Testing seed moisture after mechanical processing
18. What is participatory plant breeding?
    • Involving farmers and other stakeholders in the selection and evaluation of breeding materials
    • Conducting all selection exclusively in a laboratory
    • Selecting varieties without considering farmers' production conditions
    • Releasing varieties without field evaluation
19. What is the principal purpose of a variety maintenance programme?
    • Preserving the genetic identity and characteristic purity of a released variety
    • Creating random mixtures of different varieties
    • Increasing the number of off-type plants in seed stocks
    • Changing the defining characteristics of a variety every season
20. Why are wild relatives of cultivated crops important in plant breeding?
    • They can provide useful genes for traits such as disease resistance and stress tolerance
    • They always produce higher yields than cultivated varieties
    • They eliminate the need for genetic evaluation
    • They contain no useful genetic variation