Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: One dimensional motion describes objects moving in straight lines. Speed is a scalar measure of how quickly an object is moving along this line. Velocity is speed with a direction, making it a vector. If an object's velocity changes with time, the object is said to be accelerating. When restricted to one dimension, there are only two possible directions for the velocity and acceleration vectors to point in. As we'll see in the next chapters, understanding an object's acceleration is the key to understanding its motion. Answer: speed
[EX A]: What is the term for a scalar measure of how quickly an object is moving along this line?

[EX Q]: Passage: Christopher Auyeung, using bat image by User:Rugby471/Wikimedia Commons. Bats use echolocation to identify the location of objects . CC BY-NC 3.0 (bat image available under public domain). Answer: echolocation
[EX A]: What do bats use to determine the location of objects?

[EX Q]: Passage: A vesicle. Because vesicles are made of phospholipids, they can break off of and fuse with other membraneous material. This allows them to serve as small transport containers, moving substances around the cell and to the cell membrane. Answer: phospholipids
[EX A]:
What are vesicles made of?