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प्रश्न
Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition.
उत्तर
It is true that many apomicts posses normal-looking embryo sacs. The only possibility of the embryo sac possessing diploid cells is due to failure of meiotic division at the megaspore mother cell stage. Since, the megaspore mother cell has a dipoid nucleus, if it undergoes mitosis instead of meiosis, all the resulting nuclei and cells will be diploid in nature.
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संबंधित प्रश्न
From among the sets of terms given below, identify those that are associated with the gynoecium.
From the statements given below choose the option that are true for a typical female gametophyte of a flowering plant.
- It is 8-nucleate and 7-celled at maturity
- It is free-nuclear during the development
- It is situated inside the integument but outside the nucellus
- It has an egg apparatus situated at the chalazal end
The embryo sac is ______
The method of embryo sac forming from a single megaspore is called ______.
In an embryo sac, the cells that degenerate after fertilisation are ______.
In a flower, if the megaspore mother cell forms megaspores without undergoing meiosis and if one of the megaspores develops into an embryo sac, its nuclei would be ______.
Draw the diagram of a mature embryo sac and show its 8-nucleate, 7-celled nature. Show the following parts: antipodals, synergids, egg, central cell, polar nuclei.
With a neat, labelled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.
Trace the development of a megaspore mother cell to the formation of a mature embryo sac in a flowering plant.
Draw a diagram of the mature embryo sac of an angiospermic ovule and label any four parts in it.
