Which process involves breaking off a body part that can regrow?

The process that involves breaking off a body part that can regrow is known as fragmentation or regeneration. This is a form of asexual reproduction commonly observed in certain organisms such as starfish, planarians, and some types of worms. In fragmentation, an organism can split into pieces, and under suitable conditions, these pieces can develop into new individuals. The ability to regenerate lost body parts is also an essential aspect of this process, allowing the organism to recover from injury or reproduce. This remarkable capability reflects a unique biological adaptation that enhances survival in various environments.

The other processes mentioned do not involve the same mechanism of regenerating lost body parts. Mitosis is a type of cell division for growth and repair, while fission refers to a process where an organism divides into two or more parts, each capable of growing into a new organism, but it does not specifically entail the regrowth of a lost part. Crossing over is a genetic process that occurs during meiosis, where sections of DNA are exchanged between homologous chromosomes, and is unrelated to body part regeneration.