A student wants to prove that amphibians appeared on earth before birds. The student should use the fossil findings as evidence to provide the most reliable information about the periods when amphibians and birds appeared on earth. Fossils would throw light on the internal body structures that bear the closest similarity to either the amphibians or the birds. The radiocarbon dating of the fossils will reveal its age. This can be used to figure out the time of divergence of the two types.
Answer: A . Has its collagen fibers randomly orientated.
Explanation:
In the microscopic anatomy of the bone, an osteon (basic microscope unit of the bone) can be arranged into two categories; woven bone or lamellar bone.
As the name suggests woven bone is characterized by the random orientation of the collagen fibers . These collagen fibers haphazardly form to give the visual appearance of an intertwined (woven) network of collagen fibers.
Due to the randomness of the collagen fibers orientation woven bone is thus mechanically weaker than lamellar bone. Woven bone is formed/produced when osteoblasts produce osteoids rapidly within the bone matrix thus woven bone has the ability to form quickly as needed.
Woven bone is thus immature bone or pathologic bone with no stress orientation, it has a high percentage of osteocytes per unit volume and a high rate of turnover.
Some examples could be Giraffes with long necks and the darkening of London's peppered moths after the industrial revolution. Direct selection is the shift of the population of one species towards a certain phenotype. -reference.com
