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

Ex Input:
Passage: The jointed appendages of arthropods may be used as legs for walking. Being jointed makes them more flexible. Try walking or climbing stairs without bending your knees, and you'll see why joints are helpful. In most arthropods, the appendages on the head have been modified for other functions. Figure below shows some of the head appendages found in arthropods. Sensory organs such as eyes are also found on the head. Answer: walking

Ex Output:
What may the jointed appendages of arthropods be used for?

Ex Input:
Passage: Figure 5.3 This phospholipid molecule is composed of a hydrophilic head and two hydrophobic tails. The hydrophilic head group consists of a phosphate-containing group attached to a glycerol molecule. The hydrophobic tails, each containing either a saturated or an unsaturated fatty acid, are long hydrocarbon chains. Answer: hydrophillic head , and hydrophobic tails

Ex Output:
What two things are a phospholipid molecules composed of?

Ex Input:
Passage: A transverse wave can be characterized by the high and low points reached by particles of the medium as the wave passes through. This is illustrated in Figure below . The high points are called crests, and the low points are called troughs. Answer: crests

Ex Output:
What are the high points of a transverse wave called?