JAMB - Biology (2025 - No. 10)
Explanation
Epigeal germination is the botanical term for the process where the cotyledons are carried above the soil surface during seed germination. This occurs due to the rapid elongation of the hypocotyl (the part of the embryonic stem below the cotyledons), which pushes the cotyledons upwards, often forming a hook shape to break through the soil. Once exposed to light, the cotyledons often turn green and perform photosynthesis to provide energy for the developing seedling until the true leaves form.
A. Epicotyl: The epicotyl is the portion of the embryonic stem above the cotyledons. In hypogeal germination, it elongates to push the shoot tip above ground while the cotyledons remain below. It is not the name of the germination type itself.
C. Hypocotyl: The hypocotyl is the part of the stem below the cotyledons that elongates in epigeal germination, but it is a plant part, not the name of the overall germination process.
D. Hypogeal: Hypogeal germination is the opposite type, where the cotyledons remain below the soil surface. The epicotyl elongates in this case.
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