biology : class12 Coleoptile Development : Dicot Embryo, Monocot Embryo, Embryonic Axis, Cotyledons : Embryo Development MCQ Questions and Answers
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Coleoptile Development
MCQ questions and answers.
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MCQ Questions
1. During monocot embryo development, which structure directly encloses and protects the plumule as it develops into the embryonic shoot?
A.
Coleorhiza
B.
Scutellum
C.
Coleoptile
D.
Suspensor
Correct Answer:
Coleoptile
Explanation:
The coleoptile is a protective sheath surrounding the plumule, including the embryonic shoot apex and young leaf primordia, during early monocot development.
2. A mutation prevents the formation of the coleoptile in a grass embryo but leaves the plumule itself structurally intact. Which developmental process would be most directly impaired?
A.
Protection of the emerging plumule during soil penetration
B.
Transfer of nutrients from endosperm to the embryo
C.
Formation of the embryonic root cap
D.
Attachment of the embryo to the ovule wall
Correct Answer:
Protection of the emerging plumule during soil penetration
Explanation:
The coleoptile functions as a protective sheath for the developing plumule, especially as the shoot penetrates the soil. Nutrient transfer is primarily associated with the scutellum.
3. Which combination correctly identifies the developmental relationship between the coleoptile and the plumule in a monocot embryo?
A.
The coleoptile is the embryonic root, whereas the plumule forms the root cap
B.
The coleoptile is a sheath surrounding the plumule, whereas the plumule contains the embryonic shoot apex
C.
The coleoptile absorbs endosperm nutrients, whereas the plumule forms the scutellum
D.
The coleoptile develops from the radicle, whereas the plumule develops from the coleorhiza
Correct Answer:
The coleoptile is a sheath surrounding the plumule, whereas the plumule contains the embryonic shoot apex
Explanation:
The coleoptile and plumule are distinct embryonic structures: the coleoptile provides protective covering, while the plumule represents the young shoot region enclosed by it.
4. When a grass seedling emerges, the shoot tip remains protected while the coleoptile grows upward through the soil. Which feature best explains this protective role?
A.
The coleoptile forms a sheath around the plumule and bears the mechanical stress of emergence
B.
The coleoptile develops into the primary root and anchors the seedling
C.
The coleoptile digests the endosperm and supplies sugars directly to the radicle
D.
The coleoptile replaces the scutellum as the principal absorptive organ
Correct Answer:
The coleoptile forms a sheath around the plumule and bears the mechanical stress of emergence
Explanation:
The coleoptile encloses the plumule and protects its delicate shoot apex and young leaves while the seedling passes through the soil.
5. A researcher removes the coleoptile from a germinating maize embryo while leaving the scutellum and plumule undamaged. Which immediate consequence is most likely?
A.
The plumule loses its specialized protective covering during emergence
B.
The embryo loses its only connection with the endosperm
C.
The radicle can no longer emerge from the seed
D.
The scutellum can no longer function as a cotyledon
Correct Answer:
The plumule loses its specialized protective covering during emergence
Explanation:
Removal of the coleoptile directly exposes the plumule. The scutellum remains the cotyledonary structure involved in nutrient transfer, and the radicle is protected by the coleorhiza.
6. Which observation most specifically indicates that coleoptile development has occurred in a monocot embryo?
A.
A sheath is present around the embryonic shoot apex and young leaf primordia
B.
A single cotyledon is connected to the endosperm
C.
A root cap surrounds the embryonic radicle
D.
A suspensor connects the embryo to the ovule wall
Correct Answer:
A sheath is present around the embryonic shoot apex and young leaf primordia
Explanation:
Coleoptile development is recognized by the formation of a sheath enclosing the plumule, which consists of the embryonic shoot apex and its young leaves.
7. In a developing grass embryo, which pairing correctly distinguishes the protective coverings of the two embryonic poles?
A.
Coleoptile around the plumule and coleorhiza around the radicle
B.
Coleorhiza around the plumule and coleoptile around the radicle
C.
Scutellum around the plumule and coleoptile around the radicle
D.
Coleoptile around the scutellum and coleorhiza around the endosperm
Correct Answer:
Coleoptile around the plumule and coleorhiza around the radicle
Explanation:
The coleoptile is the sheath associated with the embryonic shoot or plumule, whereas the coleorhiza protects the embryonic root or radicle.
8. If the embryonic shoot apex of a grass embryo is experimentally displaced but remains enclosed within the coleoptile, which interpretation is most accurate?
A.
The coleoptile is a protective sheath and does not itself represent the shoot apex
B.
The coleoptile must be the primary meristem because it encloses the shoot apex
C.
The displaced shoot apex will automatically become the scutellum
D.
The coleoptile is equivalent to the embryonic root because it surrounds an axis
Correct Answer:
The coleoptile is a protective sheath and does not itself represent the shoot apex
Explanation:
Enclosure does not imply identity. The coleoptile surrounds and protects the plumule, while the shoot apex remains the meristematic region of the embryonic shoot.
9. Which developmental defect would most specifically be attributed to abnormal coleoptile formation rather than abnormal scutellum formation?
A.
Failure of the emerging plumule to remain protected by a sheath
B.
Reduced transfer of assimilates from the endosperm to the embryo
C.
Loss of the embryo's single cotyledonary organ
D.
Impaired absorption of endosperm reserves by the cotyledon
Correct Answer:
Failure of the emerging plumule to remain protected by a sheath
Explanation:
Abnormal coleoptile formation compromises protection of the plumule. Scutellum defects primarily affect cotyledonary nutrient absorption and transfer from the endosperm.
10. A developmental diagram of a monocot embryo shows a sheath enclosing several young leaf primordia and the shoot apical region. Which label should be assigned to this sheath?
A.
Scutellum
B.
Coleoptile
C.
Coleorhiza
D.
Radicle
Correct Answer:
Coleoptile
Explanation:
A sheath enclosing the plumule, including the shoot apical region and young leaf primordia, is the coleoptile. The scutellum is the single cotyledon, while the coleorhiza surrounds the radicle.
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