Question

A typical angiospermic embryo sac is $8$- nucleate and

• A. Single celled
• B. Seven celled
• C. Eight celled
• D. Four celled

Answer 1

The correct option is B Seven celled

• The embryo sac is formed from the megaspore mother cell by the process of megasporogenesis and mega-gametogenesis.
• A diploid Megaspore mother cell is developed inside the nucellus.
• It then undergoes meiotic division to form four haploid megaspores. This process is called megasporogenesis.
• Out of these four megaspores, three degenerate and only one remains functional which develops into embryo sac and this process is called megagametogenesis.
• This functional megaspore then undergoes mitosis three times without cytoplasmic divisions which results in 8 nuclei in the megaspore.
• Three of these 8 nuclei get organized into egg apparatus (consisting of an egg cell and two synergids) at the micropylar pole, two nuclei form a large central cell and three nuclei get organized in antipodal cells at the chalazal pole.
• This results in the formation of a 7-celled but 8-nucleate structure which is called the embryo sac.

So, the correct answer is option B.