Advertisements
Advertisements
Question
Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition.
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
From among the sets of terms given below, identify those that are associated with the gynoecium.
The embryo sac is ______
The method of embryo sac forming from a single megaspore is called ______.
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 ______.
Name the component cells of the ‘egg apparatus’ in an embryo sac.
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.
Draw a diagram of the mature embryo sac of an angiospermic ovule and label any four parts in it.
During the development of the female gametophyte, the functional megaspore undergoes mitotic divisions without immediate cell wall formation. What are these divisions called?
In the first mitotic division of the functional megaspore, the two daughter nuclei move to opposite poles of the enlarging megaspore. What stage is this called?
Following the 2-nucleate stage, both nuclei divide simultaneously during the second mitotic division. What is the resulting stage called, and how many nuclei are at each pole?
The central cell of the mature embryo sac contains two polar nuclei. What is the ploidy level of the central cell after the two polar nuclei fuse?
The mature embryo sac is described as monosporic and of the Polygonum type. What does the term monosporic indicate about the origin of the embryo sac?
Based on the cell distribution table, which cell or group of cells contributes a haploid gamete nucleus during double fertilization?
How many mitotic divisions are required to convert the haploid functional megaspore into the 8-nucleate stage?
In the mature embryo sac, which structure contains the filiform apparatus that aids in guiding the pollen tube?
