Question

In a 7 celled and 8 nucleated embryosac :
(a) The polar nuclei are situated below the egg apparatus in central cell
(b) Egg apparatus has two synergids and one egg cell at micropylar end
(c) Filiform apparatus in synergids direct the pollen tube to enter into egg cell
(d) Antipodal cells are haploid but have different genetic composition to that of egg cell
How many above statements are true for statement given in the question?

• A. Two
• B. Three
• C. One
• D. Four

Answer 1

The correct option is B Three

• A functional megaspore gives rise to an embryo sac or the female gametophyte.
  
• The functional megaspore undergoes 3 successive mitotic divisions to form the 8-nucleate embryo sac.
• The first mitotic division forms two nuclei out of which one nucleus moves towards the micropylar region and the other nucleus moves towards the chalazal region.
• These nuclei further divide at respective ends and re-divide to form eight nucleate cell and there are four nuclei at each end.
• At the micropylar end, only three out of four nuclei differentiate and form two synergids and one egg cell and are known as the egg apparatus.
• At the chalazal end, three out of four nuclei differentiate as antipodal cells and the remaining two cells (of the micropylar and the chalazal end) move towards the centre and form the polar nuclei, which are situated in a large central cell.
• Hence, the embryo-sac is called 7-celled and 8 nucleated embryosacs.

a) The polar nuclei are situated above the egg apparatus in the central cell.

All the other statements are true.

So, the correct answer is 'Three'.