When did hans and zacharias janssen contribute to the cell theory

In the context of the neural impulse, which of the following is true about the depolarization of neuron membranes?

What happens when the cell copies its chromosomes

Match the examples to the correct level of organization. 1. system level roses, snakes, puppies 2. organism level roots, stamens, leaves 3. tissue level bone, cartilage, blood 4. organ level heart, veins, arteries