In a hypothetical organism, at a four-celled embryonic stage, blastomere 'X' instructs one of the daughter cells of an adjoining blastomere 'Y' to take the fate 'Ya'. The other daughter cell takes the fate 'Yp'. This is illustrated in the figure below as lineages for Y a and Yp. If the X blastomere is removed, both daughter cells take up the Yp fate.

This instruction is mediated by a paracrine factor, Pap2 secreted by X blastomere interacting with Pap5 present on the membrane of Y blastomere.

The following experimental manipulations were carried out, which involved creating partial genetically mosaic embryos in vitro and following the fate of the Y blastomere.

Which one of the mosaics will show a developmental pattern similar to that when blastomere X is removed?

1
X blastomere null for Pap2 and wild type Y blastomere
2
Wild type X blastomere and constitutively activated Pap5 Y blastomere
3
X blastomere null for Pap2 and constitutively activated Pap5 Y blastomere
4
X blastomere null for Pap5 and wild type Y blastomere

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