The formation of bone from a cartilaginous model is termed

Evolution

Explanation:

Evolution is the gradual directional change especially one leading to a more advanced or complex form

From a cartilaginous model, bone evolved into existence because it is STRONGER, AND MORE RESISTANT to diseases and external conditions than the preceding Cartilage.

Note that the aim of Evolution is to expressed traits with highest survival rate; so, there is BONE.

step 1: replication fork formation.

step 2: primer binding.

step 3: elongation.

step 4: termination.

explanation:

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blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.