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

[Q]: Seeds of a pine cone are easily carried by the wind and dispersed because seeds have wings.
[A]: Why are seeds of a pine cone easily carried by the wind and dispersed?


[Q]: Simple carbohydrates can be classified in terms of chain length.
[A]: Which carbohydrates can be classified in terms of chain length?


[Q]: The presence of a nucleus is the main difference between prokaryotic or eukaryotic cells .
[A]:
What is the main difference between prokaryotic or eukaryotic cells ?