Does anyone know how to whistle with grass if not then look it up :)

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

Cell specialization occurs by the process ofa. reproductionb. differentiationc. maturationd. growth

When analyzing tree rings, what do scientists assume a thin ring indicates?