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