Why is it we cannot directly observe a genotype, but can sometimes infer it?

What re the two main phrases of the cell cycle.

What is the main difference between the central nervous system (cns) and the peripheral nervous system (pns)? .the cns involves the brain and spinal cord, and the pns involves the body nerves. the cns involves the body nerves, and the pns involves the brain and spinal cord. the cns involves sensory neurons, and the pns involves motor neurons. the cns involves motor neurons, and the pns involves sensory neurons.

Which measurement unit represents volume? liter kilometer square centimeter centigram