Final answer:
The size of sperm cells in male Drosophila bifurca is exceptionally large, reaching up to 5.8 cm, in contrast to human sperm cells which are the smallest cells in the human body with a head only 5 µm long. Human sperm are produced in large quantities (100 to 300 million daily) and are designed for mobility and fertilization.
Step-by-step explanation:
The size of sperm cells in male Drosophila bifurca is remarkably large compared to human sperm cells, with sizes reaching up to 5.8 cm long. While human sperm cells are the smallest cells in the human body with a head of only 5 µm long and an overall structure consisting of a distinctive head, mid-piece, and tail region, the Drosophila bifurca sperm far exceed this size. The head of a sperm contains the genetic material required for fertilization, and this haploid nucleus is very compact with minimal cytoplasm, leading to the small size of the sperm cell. In contrast, Drosophila bifurca sperm cells are several centimeters long due to extreme evolutionary adaptations that aren't fully understood.
Approximately 100 to 300 million human sperm are produced each day, demonstrating a stark contrast in the quantity produced when comparing the size and numbers. While a human sperm might be smaller, their huge numbers and motility—powered by ATP from tightly packed mitochondria in the mid-piece—are essential for fertilization. The sperm utilize a flagellum for movement, allowing these tiny gametes to journey toward fertilization with an oocyte.