I believe that hair and limbs are homology because all mammals have hair and similar limb structure. Hair loss and social behavior on the other hand are homolasy because not all mammals have them. Homology is the similar traits due to common ancestry while homoplasy is similar traits for other reasons other than common ancestry.
There are four main organelles:
Nucleus
Ribosome
Rough Endoplasmic Reticulum
Golgi Apparatus
However, the ribosome is the most responsible for making protein, even though the other 3 are also important. It isn't a cell organelle but a cell structure that produces proteins.
a because the marble changed its position quickly meaning that it was in motion
The process by which cell types or cell populations attain distinct and different forms and functions is called differentiation.
This is the process that allows the stem cells to differentiate and form a cell type that will perform a specific function.
The process of differentiation is essential for the formation of the different organs in multicellular organisms.