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