Please help with this hard SCIENCE work!!

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

Why is taking care of yourself a time management techique

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.