Question

A diploid structure present in the embryo sac is

• A. Oosphere
• B. Secondary nucleus
• C. Synergids
• D. Antipodal cells

Answer 1

The correct option is B Secondary nucleus

A mature embryo sac is a 7-celled and 8-nucleate structure. At the micropylar end, is present the egg apparatus which consists of one egg cell or oosphere and two synergids ,thus, 3 nuclei are contained in egg apparatus. Other three nuclei are contained in three Antipodal cells present at the chalazal end. The rest two nuclei form a large central cell present in the centre of the embryo sac. The two polar nuclei get fused prior to fertilisation and form a diploid secondary nucleus.

Hence, in an embryo sac, the diploid structure is the secondary nucleus.

So, the correct answer is B.