Question

Tetrasporic embryo sac is formed in
A) Polygonum type
B) Allium type
C) Peperomia type
D) Pisum type

Answer 1

Hint: The Embryo sacs are haploid, egg-producing structures that constitute the female gametophyte. The tetrasporic embryo sac is formed from four megaspores nuclei.

Complete Answer:
- The megaspore is divided into four megaspores, that sometimes are not followed by the cytokinesis. So, all the newly formed cells lie in a single cell. This single cell is termed as coeno-megaspore.
- This further participates in the formation of the embryo sac. The embryo sac formed by this process is called a tetrasporic embryo sac.
- This type of embryo sac is found in peperomia. The four haploid nuclei further divide into 16 nuclei by mitotic division.
- Allium type embryo sac is monosporic, or Polygonum-type embryo sac is commonly found in angiosperms. This kind of embryo sac is formed from one megaspore, that is why it is termed s monosporic embryo sac.
- The functional megaspore divides and undergoes three successive mitotic cell divisions to produce eight nuclei. The monosporic embryo sac is developed from the chalazal portion of the functional megaspore.

Note: The mitosis and meiosis are types of cell division. In mitosis, the cell divides into two genetically identical daughter cells. On the contrary, the meiosis produces four daughter cells that are not identical, genetically. mitosis involves only one cell division while meiosis involves two successive cell divisions.