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

Example Input: Passage: Resistance is the property that determines the amount of current flow through a particular material. Answer: resistance
Example Output: What is the property that determines the amount of current flow through a particular material?

Example Input: Passage: The energy in sunlight, or solar energy, can be used to heat homes. It can also be used to produce electricity in solar cells. However, solar energy may not be practical in areas that are often cloudy. Answer: solar energy
Example Output: The energy in sunlight is also known as what kind of energy?

Example Input: Passage: Echinoderms lack respiratory and excretory systems. Instead, the thin walls of their tube feet allow oxygen to diffuse in and wastes to diffuse out. Echinoderms also lack a centralized nervous system. They have an open circulatory system and lack a heart. On the other hand, echinoderms have a well-developed coelom and a complete digestive system. Echinoderms use pheromones to communicate with each other. They detect the chemicals with sensory cells on their body surface. Some echinoderms also have simple eyes ( ocelli ) that can sense light. Like annelids, echinoderms have the ability to regenerate a missing body part. Answer: centralized nervous system
Example Output:
Echinoderms lack what type of system that in humans consists of the brain and spinal cord?