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Which of the following statements is/are correct? 1. Monosporic development is the method of embryo sac formation from a single megaspore. 2. The egg apparatus consists of two synergids and one egg cell.

Which of the following statements is/are correct? 1. Monosporic development is the method of embryo sac formation from a single megaspore. 2. The egg apparatus consists of two synergids and one egg cell. Correct Answer Both 1 and 2

The correct answer is Both 1 and 2.

Key Points

Female gametophyte

  • In a majority of flowering plants, one of the megaspores is functional while the other three degenerate.
  • Only the functional megasFpore develops into the female gametophyte (embryo sac).
  • This method of embryo sac formation from a single megaspore is termed monosporic development. 
    • ​Hence statement 1 is correct.
  • The nucleus of the functional megaspore divides mitotically to form two nuclei which move to the opposite poles, forming the 2-nucleate embryo sac.
  • Two more sequential mitotic nuclear divisions result in the formation of the 4-nucleate and later the 8-nucleate stages of the embryo sac.
  • It is of interest to note that these mitotic divisions are strictly free nuclear, that is, nuclear divisions are not followed immediately by cell wall formation.
  • After the 8-nucleate stage, cell walls are laid down leading to the organization of the typical female gametophyte or embryo sac.
  • Six of the eight nuclei are surrounded by cell walls and organized into cells; the remaining two nuclei, called polar nuclei are situated below the egg apparatus in the large central cell.
  • There is a characteristic distribution of the cells within the embryo sac.
  • Three cells are grouped together at the micropylar end and constitute the egg apparatus.
  • The egg apparatus, in turn, consists of two synergids and one egg cell.
    • Hence statement 2 is correct.​

Additional Information

  • The synergids have special cellular thickenings at the micropylar tip called filiform apparatus, which play an important role in guiding the pollen tubes into the synergid.
  • Three cells are at the chalazal end and are called the antipodals.
  • The large central cell, as mentioned earlier, has two polar nuclei.
  • Thus, a typical angiosperm embryo sac, at maturity, though 8-nucleate is 7-celled

Related Questions

Consider the following statements regarding recurrent type apomixis and choose the correct answer:
1. There is meiosis during the formation of megaspore
2. The embryo sac is diploid in nature
3. The embryo sac never develops from a cell of the archesporium
4. The development of embryo from a cell of an embryo sac other than egg is known as apospory
Consider the following statements and choose the correct answer:
1. In Oenothera type of monosporic embryo sac, the embryo develops from the micropylar megaspore of the tetrad
2. Antipodal cells are altogether absent in Oenothera type
3. The genus Trapa forms an 8-nucleate embryo sac of the Polygonurn type
4. Oenothera type of embryo sac development has been found to be a characteristic feature of the entire family Onagraceae
A monosporic, tetranuclear embryo-sac having an egg apparatus composed of two synergids and one egg, and a single polar nucleus is characteristic of all the members of
Consider the following statements.
1. Fertilisation of the egg takes place inside the embryo sac.
2. Fertilised ovum form the embryo.
3. Endosperm is generally triploid.
Which of the statements given above are correct?
The development of embryo from the antipodal cells or synergids other than egg cell is known as
Consider the following statements regarding double fertilization and choose the correct answer:
1. At the time of the sperm's approach to the egg nucleus, the male nucleus has the appearance of a continuous thread rolled into a ball
2. It is only the presence of the two nucleoli which serves to distinguish the fertilized egg from the unfertilized egg
3. Finally, the male nucleolus increases in size and fuses with the female nucleolus thus closing the phenomenon of sexual union of the nuclei
4. The fusion of the male gamete with the secondary nucleus results in the formation of a sister embryo
Consider the following statements regarding poloyembryony and choose the correct answer:
1. False polyembryony includes the development of two or more embryo sacs within the Same nucellus, and the embryos are derived from different embryo sacs
2. In cleavage polyembryony, the zygote instead of giving rise to one embryo produces embryos by cleavage
3. According to Jeffrey (1895), in Erythronium americanum the "embryogenic mass" forms two or three embryos
When the embryo is formed from any cell of the embryo sac other than the egg, the phenomena is called as
From one megaspore mother cell number of megaspore finally produced is
Embryo sac is monosporic when it dovelops from