Which one of the following about development of sea urchin embryos is TRUE?
1
Each blastomere of a 4-cell stage possesses a portion of the original animal-vegetal axis and if isolated and allowed to develop will form a complete but smaller sized larva.
2
Each blastomere of a 8-cell stage has the capacity to form a complete embryo but by the 16 -cell stage, blastomeres will develop according to their presumptive fate.
3
Any blastomere isolated till the pluteus larva formation will regulate to go on and develop into a full sized embryo.
4
After an intricate recombination at the 16-cell stage, the resulting embryo looses its ability to form a complete larva.