Skeletal muscle! (or striated muscle).
There’s no diagraaaammmmm.
Answer:
An event can cause changes to occur in one or more of the spheres, and/or an event can be the effect of changes in one or more of Earth's four spheres. This two-way cause and effect relationship between an event and a sphere is called an interaction. Interactions also occur among the spheres.
Stem cells are what allow planaria to grow and regenerate as the stem cells can change into any of the cells that make up the planaria.
According to ChaCha.com, "Parthenogenesis is a form of agamogenesis in which an unfertilized egg develops into a new individual. Parthenogenesis occurs naturally in many plants and invertebrates. This differs from other forms of asexual reproduction because an egg is used."
