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

The newest, outer layers of secondary xylem are called sapwood.
What are the newest, outer layers of secondary xylem called?

You call materials able to conduct electricity with 100% efficiency, meaning that no energy is lost during the electrical transmission, superconductors.
What do you call materials able to conduct electricity with 100% efficiency, meaning that no energy is lost during the electrical transmission?

Large mutations is essential for forming new genes.
What is essential for forming new genes?