Given a scientific question, generate a correct answer to it.

[EX Q]: What is at the surface of a cell, arranged in similar bilayer?
[EX A]: phospholipids

[EX Q]: What are the two types of vascular tissues found in vascular plants?
[EX A]: xylem and phloem

[EX Q]: Varves form in lakes covered by what?
[EX A]:
ice