(04.01 lc) the levels of organization within an organism are atom, cell, tissue, organ, and atomic number; element compound; kidney molecule; organ system nucleus; membrane

Answer is molecule; organ system.

The atom is the smallest unit of matter. The union of two atoms or more form molecules. The simplest level of organization for living things is a single cell organelle, which is composed of many molecules. The biological levels of organization of living things arranged from the simplest to most complex are: organelle, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem, and biosphere.