instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: Triglycerides are the main form of stored energy in animals. This type of lipid is commonly called fat. Triglycerides are composed of a glycerol and three fatty acid chains. An example is shown in Figure below . In humans, triglycerides are a mechanism for storing unused calories, and their high concentration in blood correlates with the consumption of excess starches and other carbohydrate-rich foods. Answer: triglycerides
answer:
What stored form of energy is made up of glycerol and three fatty acid chains?

question:
Passage: Density is defined as the mass of an object divided by its volume. Propose a unit of density in terms of the fundamental SI units. Answer: volume
answer:
Density is defined as the mass of an object divided by its what?

question:
Passage: The heart is a muscular organ in the chest that consists mainly of cardiac muscle. It pumps blood through blood vessels by repeated, rhythmic contractions. Blood flows through four chambers of the heart when it beats. Heartbeat is controlled by electrical signals from special cells within the heart called the pacemaker. Answer: cardiac muscle
answer:
What type of muscle makes up most of the heart?