Question
In angiosperms, zygote is diploid while primary endosperm cell is triploid. Explain.
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Answer
Zygote is the product of a fusion of a haploid male gamete and haploid female gamete, i.e. egg cell. Therefore, it is diploid.
$\text{Male gamete} + \text{Egg }\xrightarrow{\ \ }\text{Zygote}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{(n)} + \text{(n)} \xrightarrow{}\text{(2n)}$
Whereas, primary endosperm cell is a product of fusion of secondary necleus (2n) and a haploid male gamete. So, it is triploid.$\text{Secondary nucleus} +\text{ Male gamete}\xrightarrow{}\text{Primary endosperm cell}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2\text{n)} +\text{ (n)}\xrightarrow{}\text{ (3n)}$
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