How to Identify and Classify Yams
  • 1. What is the primary difference between yams and sweet potatoes?
A) Yams are always sweeter than sweet potatoes.
B) Yams are monocots, sweet potatoes are dicots.
C) Yams are orange, sweet potatoes are white.
D) Yams are grown in America, sweet potatoes are not.
  • 2. True yams belong to which plant family?
A) Convolvulaceae
B) Solanaceae
C) Dioscoreaceae
D) Fabaceae
  • 3. Which characteristic is NOT typically used to identify yam species?
A) Tuber shape
B) Flower color
C) Stem morphology
D) Leaf venation
  • 4. Which continent is the origin of most yam species?
A) North America
B) South America
C) Africa
D) Asia
  • 5. What is the function of the nodes on a yam vine?
A) To attract pollinators
B) To absorb water from the air
C) To defend against predators
D) To produce leaves and aerial tubers
  • 6. What term describes the arrangement of leaves on a yam vine?
A) Whorled
B) Alternate or opposite
C) Linear
D) Parallel
  • 7. What is a 'head' when referring to yams?
A) The top portion of the tuber where vines grow.
B) The flowering part of the yam plant.
C) The protective skin of the tuber.
D) The root hairs on the tuber.
  • 8. Which yam species is known for its medicinal properties and bitter taste?
A) Dioscorea alata (Water yam)
B) Dioscorea rotundata (White yam)
C) Dioscorea villosa (Wild yam)
D) Dioscorea esculenta (Lesser yam)
  • 9. What is the common name for Dioscorea alata?
A) Chinese yam
B) White yam
C) Air potato
D) Water yam
  • 10. How are yams typically propagated?
A) By grafting
B) By leaf cuttings
C) By seeds
D) By planting tuber pieces
  • 11. What does the term 'dormancy' refer to in yam cultivation?
A) Flowering season
B) Rapid vine growth
C) Susceptibility to disease
D) A period of inactivity in the tuber
  • 12. Which of the following is NOT a characteristic of yam tubers?
A) Starchy texture
B) Potential for toxicity in some species
C) Variable size and shape
D) Uniform color across all species
  • 13. What is the significance of 'aerial tubers' or bulbils in some yam species?
A) They indicate the yam is ready to harvest.
B) They are the primary source of food storage.
C) They serve as a form of vegetative propagation.
D) They are a sign of disease.
  • 14. Which yam species is also known as the 'Chinese yam'?
A) Dioscorea trifida
B) Dioscorea bulbifera
C) Dioscorea polystachya
D) Dioscorea cayenensis
  • 15. What type of climate is most suitable for yam cultivation?
A) Desert
B) Temperate
C) Arctic
D) Tropical and subtropical
  • 16. What is the primary use of yams globally?
A) For medicinal purposes only
B) As animal feed
C) As a staple food crop
D) For ornamental purposes
  • 17. Which of these characteristics helps distinguish Dioscorea rotundata from other yams?
A) White flesh and cylindrical shape
B) Hairy vines and small tubers
C) Extremely bitter taste
D) Purple skin and round shape
  • 18. What is 'dioscorine'?
A) A growth hormone in yams.
B) A type of starch found in yams.
C) A natural pesticide produced by yams.
D) A toxic alkaloid found in some yam species.
  • 19. What is the best soil type for growing yams?
A) Well-drained, fertile loam
B) Sandy, infertile soil
C) Waterlogged soil
D) Heavy clay soil
  • 20. Which of these pests is a common problem in yam cultivation?
A) Caterpillars
B) Aphids
C) Yam beetles
D) Grasshoppers
  • 21. What is a key indicator of yam maturity for harvesting?
A) Appearance of aerial tubers
B) Drying of the vines
C) Sudden increase in tuber size
D) Flowering of the plant
  • 22. What does 'Dioscorea' refer to?
A) The genus of true yams
B) A disease that affects yams
C) A type of fertilizer used for yams
D) A yam harvesting technique
  • 23. What is a common method for reducing toxicity in wild yams before consumption?
A) Sun drying
B) Refrigeration
C) Prolonged boiling
D) Fermentation
  • 24. Which of the following is a characteristic of Dioscorea esculenta (Lesser yam)?
A) Very large, single tubers.
B) Extremely hairy vines.
C) Smaller tubers often produced in clusters.
D) Highly bitter taste.
  • 25. What is the 'Air Potato' (Dioscorea bulbifera) primarily propagated by?
A) Underground tubers
B) Seeds
C) Root cuttings
D) Aerial tubers (bulbils)
  • 26. In yam classification, what does 'morphology' refer to?
A) The genetic makeup of the plant.
B) The growing season length.
C) The physical form and structure of the plant.
D) The taste of the tuber.
  • 27. Which of the following is a significant disease affecting yam crops?
A) Citrus canker
B) Potato blight
C) Wheat rust
D) Yam mosaic virus
  • 28. Which yam species is known to have a high dry matter content?
A) Dioscorea rotundata (White yam)
B) Dioscorea alata (Water yam)
C) Dioscorea trifida (Cush-cush yam)
D) Dioscorea bulbifera (Air potato)
  • 29. What is a common post-harvest practice for yams?
A) Fermenting
B) Canning
C) Freezing
D) Curing
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