Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[EX Q]: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as embryos.
[EX A]: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as what?

[EX Q]: Some viruses carry a few viral enzyme molecules within their capsids.
[EX A]: Some viruses carry a few viral enzyme molecules within their what?

[EX Q]: You call elements that contain only atoms of one type of element native elements.
[EX A]:
What do you call elements that contain only atoms of one type of element?