instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: For feeding, the insect head contains one pair of lower jaws and two pairs of upper jaws. Insects have also evolved a wide range of specialized mouthparts for eating certain foods. You can see some examples in Figure below . Answer: two pairs
answer:
How many pairs of upper jaws do insects have?

question:
Passage: The cell membrane is made up of a phospholipid bilayer, two layers of phospholipid molecules. Notice the polar head group of the phospholipid is attached to the phosphate, and the tails are two fatty acid chains. The head group and tails are attached by a glycerol backbone. Answer: cell membrane
answer:
What basic cell structure is made up of a phospholipid bilayer and two layers of phospholipid molecules?

question:
Passage: Longshore drift can erode the sediment from a beach. To keep this from happening, people may build a series of groins. A groin is wall of rocks or concrete that juts out into the ocean perpendicular to the shore. It stops waves from moving right along the beach. This stops the sand on the upcurrent side and reduces beach erosion. You can see how groins work in Figure below . Answer: groin
answer:
A wall of rocks or concrete that juts out into the ocean perpendicular to the shore is called?