Why can you not have an experiment without a hypothesis

Which term refers to the total dollar value of the goods and services produced in a country in a year?

When lactate builds up in a runners muscles it causes a burning sensation what causes this to occur

How do you know that the plant cells in these two images have different jobs, or functions? a. because all plant cells serve different functions b. because they are two different colors c. because their dna are different d. because their structures are different