Where does an embryo get its material?

Question

So by the law of thermodynamics no particle can be created or destroyed, it can only transform into a different particle.

So my questions is - where does a new life form, while still growing in a womb, gets the particles it needs to transform?

Answer 1

Thermodynamics does not govern particles - it governs energy.

The embryo is not a closed system - it is surrounded by the amniotic fluid which contains all the "particles" it needs to grow.  Just as plants grow from air, water and soil, so embryos gather everything they need from the mother.

Answer 2

An embryo is supplied nutrients by the mother, through the umbilical cord and placenta.

She gets those nutrients by eating food.

The embryo isn't "transforming" as such, it is growing by synthesising proteins, etc.

And you are misapprehending the (first) law of thermodynamics, which actually states that the total amount of energy is conserved. Matter is just "condensed" energy, so subatomic particles can be and are destroyed - they are just converted to energy.