The thoracic and sacral curvatures of the vertebral column are while the cervical and lumbar curvatures are

The thoracic and sacral curvatures of the vertebral column are convex while the cervical and lumbar curvatures are concave.

most community's take hundreds of years to become stable

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.