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

Absorption is the process by which the substances you consume are taken up by the blood.
What is the process by which the substances you consume are taken up by the blood?

The mesopause is at the top of the mesosphere.
What is at the top of the mesosphere?

Spindle fibers form between the centrioles during prophase i of meiosis process.
Spindle fibers form between the centrioles during prophase i of what process?