The part of the male reproductive cell (sperm) that contains the hereditary information passed on to a baby is the nucleus.

Here's why:

* Nucleus: The nucleus is the control center of the cell and houses the chromosomes. Chromosomes are made of DNA, which contains the genes that determine a person's traits.

* Other parts of the sperm: The sperm also has a tail for movement, a midpiece with mitochondria for energy, and an acrosome that helps it penetrate the egg. However, these parts don't carry the genetic information.

When a sperm fertilizes an egg, the nucleus of the sperm fuses with the nucleus of the egg, combining their genetic material to create a new, unique individual.