Class 12th Biology 2017 Set1 Delhi Board Paper Solution
Question 6
A mature embryo sac in a flowering plant may possess 7-cells, but 8-nuclei. Explain with the help of a diagram only.
Answer
In an ambryo-sac three cells are grouped together at the micropylar end and constitute the egg apparatus. The egg apparatus is consist of two synergids and one egg cell. The synergids have cellular thickenings at the micropylar tip called filiform apparatus, which plays an important role in guiding the pollen tubes into the synergids. Three cells are at the chalazal end and are called antipodals. Thus, a typical angiosperm ambryo-sac at maturity, though 8-nucleate is 7-celled.
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