Do all cells have a nucleus?

Which of the following is a possible reason for sleep? a) growth b)digestive c)speed d)intelligence

The observations of hooke and van leeuwenhoek documenting the existence of microscopic cells formed the basis of what important theory? a. the cell theory stating that all living things are composed of cellsb. the theory of spontaneous generation, which held that life forms could arise spontaneouslyc. the theory of chemotherapy, or use of antimicrobials to destroy pathogenic organismsd. the germ theory of disease and causative agents

Aboy jumps into a cold swimming pool and his body tempature goes down hus muscles ,blood vessels