In the monosporic embryo sac, out of the four megaspores, one megaspore at the chalazal end takes part in the formation of the embryo sac. Other three undergo programmed cell death. In the bisporic embryo sac, two megaspores take part in the formation of the embryo sac.
What is a Monosporic embryo sac?
Meiosis in the diploid megaspore mother cell divides it into 4 megaspores (haploid). With the degeneration of three, only one functional cell contributes to the embryo sac formation. This is known as monosporic embryo sac.
What is Monosporic type of development of embryo sac?
Monosporic embryo sac develops from a single megaspore and as such all the nuclei present in this type of embryo sac are genetically similar. Develops from one of the two dyads formed as a result of the first meiotic division (Meiosis I) of Megaspore Mother Cell.
Which type of embryo sac is found in plumbago?
to exhibit a normal 8-nucleate embryo sac of the Lilium type, while the last three genera, belonging to the Plumbagineae, were all found to possess a 4-nucleate sac of a unique and hitherto unde- scribed type.
What is meant by Monosporic development?
When the female gametophyte (embryo sac) develops from a single megaspore, it is called monosporic development. Usually, in most angiosperms, the megaspore mother cell divides by meiosis to form four haploid megaspores arranged in a linear fashion.
Which is an example of Bisporic type of embryo sac?
It is called the bisporic development because instead of four, two megaspores are produced as a result of meiosis in the megaspore mother cell. Each megaspore has two haploid nuclei. It is also called the Allium type of embryo sac. Therefore, the correct answer is option B.
What is meant by Monosporic condition give an example?
Which is meant by Monosporic development of female gametophyte?
megaspore
The development of the female gametophyte is considered monosporic growth from a single functional megaspore. The functional megaspore nucleus breaks mitotically to form two nuclei that shift to opposite poles. A two-nucleate embryo sac forms this.
Which is Bisporic type embryo sac?
Bisporic embryo sacs contain nuclei derived from two members of a megaspore tetrad whereas tetrasporic embryo sacs contain nuclei derived from all four members of a tetrad. Megaspores from the same tetrad are less genetically similar than are megaspores from different tetrads.
What do you understand by Bisporic embryo sac?
Why do we call embryo sac Monosporic?
Answer: When the female gametophyte (embryo sac) develops from a single megaspore, it is called monosporic development. Usually, in most angiosperms, the megaspore mother cell divides by meiosis to form four haploid megaspores arranged in a linear fashion.
What is Monosporic?
What is The bisporic type of embryo sac development?
Bisporic Type:- Bisporic type of embryo sac development is also known as allium type. In this type two of the four megaspores take part in the development of female gametophyte.
What is monosporic type of embryo sac?
Monosporic, Normal or Polygonum Type It is commonly found in plant. It is commonly called normal type. However, it was first clearly described in Polygonum. Therefore, it is also called as Polygonum type. This embryo sac has four well-defined megaspores.
What is the difference between monosporic and bisporic development?
Both phenomena have evolved multiple times. In contrast, all nuclei of monosporic female gametophytes are genetically identical. Consequently, monosporic development is predicted to be more evolutionarily stable than bisporic or tetrasporic development.
What is meant by tetrasporic embryo sac?
Tetrasporic: In this type due to failure of cytokinesis I and II a four nucleate coenomegaspore tetrad is formed and all 4 nuclei participate in formation of embryosac. Now coming to your question, development of a particular type of embryo sac depends upon the number of megaspores participating in the process.
