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Question
The family Onagraceae is marked out by which type of embryo sac?
The family Onagraceae is marked out by which type of embryo sac?
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Solution
The correct options are
A Peperomia
C Oenothera
The correct answer is D.Onagraceae family is characterized by the presence of peculiar monosporic four-nucleate Onagrad-type of embryo-sac in all its genera except Trapa. Such an embryo sac is derived from the micropylar megaspore of the tetrad. The lower three chalazal end megaspores do not disintegrate.In oenothera the mature embryo sac is organized in an egg apparatus with a uninucleate central cell it is said to be oenothera type. The micropylar megaspore of the tetrad gives rise to this embryo sac by two nuclear divisions. This results in the formation of four nuclei in the form of two synergids, egg and a polar nucleus. A third division is absent and all the nuclei are situated in the micropylar region of the developing embryo sac. Hence a lower polar nucleus and antipodal cells are absent.
A Peperomia
C Oenothera
The correct answer is D.
Onagraceae family is characterized by the presence of peculiar monosporic four-nucleate Onagrad-type of embryo-sac in all its genera except Trapa. Such an embryo sac is derived from the micropylar megaspore of the tetrad. The lower three chalazal end megaspores do not disintegrate.
In oenothera the mature embryo sac is organized in an egg apparatus with a uninucleate central cell it is said to be oenothera type. The micropylar megaspore of the tetrad gives rise to this embryo sac by two nuclear divisions. This results in the formation of four nuclei in the form of two synergids, egg and a polar nucleus. A third division is absent and all the nuclei are situated in the micropylar region of the developing embryo sac. Hence a lower polar nucleus and antipodal cells are absent.
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