1. Tardigrade
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  3. Biology
  4. By looking into the ploidy of given structures, find the ploidy of male and female plants, respectively. Nucellus: 4N; PEN: 6N

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Q. By looking into the ploidy of given structures, find the ploidy of male and female plants, respectively.
Nucellus: 4N; PEN: 6N

NTA AbhyasNTA Abhyas 2020

Solution:

Nucellus in normal condition is sporophytic (diploid, 2n), and Primary Endosperm Nucleus (PEN) is triploid (3n), which arises due to triple fusion.
The nucellus is the main parenchymatous tissue of an ovule present inside the integument. It is the central part of the ovule in which female gametophyte is present.
If the ploidy level of nucellus is 4N, then the ploidy of female parent will also be 4N.
Here, PEN = 6N, refers to the primary endosperm nucleus which is formed by the fusion of two polar nuclei and one sperm nucleus.
Which means, 6N = 2N + 2N + 2N.
Where 2N is the ploidy of each polar nuclei and the ploidy of the sperm nucleus is 2N. Therefore, the ploidy of male parent will be 2N + 2N = 4N.