Answer:
The cells lying in the deeper layer of periosteum are known as osteoblasts (bone forming cells). These cells divide continuously and form the osteocytes, thus increase the thickness of bone. ... The process of reshaping the bone is called <u>remodeling </u>and it is one of the major factors responsible for increasing size of marrow cavity.
Crossing over is essential for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.
I just found this on google
Its used to protect genetic diversity and help reintroduce into the wild.
I think the answer to this is 2.
