Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[Q]: Question: What are the narrowest blood vessels, where oxygen is transferred into body cells? Answer: capillaries
[A]: Red blood cells are flat, round, and very small. Their small size allows easy maneuverability through the capillaries, the narrowest blood vessels, where oxygen is transferred into body cells.

[Q]: Question: What is produced when hydrogen gas and oxygen gas are ignited? Answer: water
[A]: Hydrogen gas and oxygen gas are ignited to produce water.

[Q]: Question: The scientific name of an organism consists of its genus and what else? Answer: species
[A]:
The scientific name of an organism consists of its genus and species.