In the embryo sac of angiosperms, what is the correct order of the number of synergid cells, egg cell, central cell, and antipodal cells?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2–1–1–3
The mature embryo sac of most flowering plants has 8 nuclei in 7 cells. At the micropylar end lies the egg apparatus: 2 synergids and 1 egg cell. At the chalazal end lie 3 antipodal cells. The large central cell is 1 cell with 2 polar nuclei. So the counts in the order asked are synergids 2, egg 1, central cell 1 and antipodals 3, which gives 2–1–1–3. The total, 2 + 1 + 1 + 3 = 7 cells, matches the 7-celled embryo sac. A common slip is to count the two polar nuclei as two central cells.
NCERT Extract:
Female Gametophyte – “… Six of the eight nuclei are surrounded by cell walls and organised 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. … 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.”
Figure 1.8 (c) A diagrammatic representation of the mature embryo sac