Question 4
A sperm consists of a head, a middle piece and a tail. What does the middle piece do?
The right answer is the one marked above.
It is packed with mitochondria, which supply the energy. Mature sperm are motile, and swimming has to be paid for.
The nuclear material is in the head and the propelling is done by the tail — each of those is a real job, assigned here to the wrong part. A sperm is a nucleus with an engine and a propeller.