Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: Salt-water biomes in the ocean are called marine biomes.
Example Output: Salt-water biomes in the ocean are called what?

Example Input: Just as salty taste involves perception of sodium ions in saliva, sweet taste correlates with presence of glucose.
Example Output: Just as salty taste involves perception of sodium ions in saliva, what taste correlates with presence of glucose?

Example Input: There are four classes of biochemical compounds.
Example Output:
How many classes of biochemical compounds are there?