| Question | Answer |
| An electrically neutral particle in the nucleus of an atom. | Neutron |
| A type of white blood cell in which the cytoplasm does not stain with either hematoxylin or eosin. | Neutrophil |
| One of many small cytoplasmic inclusions in the nerve cell body. | Nissl Body |
| A semipermeable membrane surrounding the nucleus of a cell and separating it from the cytoplasm. | Nuclear Membrane |
| A complex type of organic acid found in chromatin. | Nucleic Acid |
| One or more bodies within the nucleus that appear to be associated with the formation of nucleoproteins. | Nucleolus |
| A general term used to identify the living material of the nucleus. | Nucleoplasm |
| A component of a nucleic molecule, consisting of a sugar, a nitrogenous base, and a phosphate group. | Nucleotide |
| The controlling unit of a cell's activities. | Nucleus |
| A type of relatively simple lipid that is fluid at ordinary temperatures. | Oil |
| The process of smelling. | Olfaction |
| The nerve passing from the eye to the occipital lobe of the cerebrum. | Optic Nerve |
| A cavity in the upper half of the anterior surface of the skull; the eye cavity. | Orbit |
| A group of tissues which function together in the performance of a definite body function. | Organ |
| The structure in the inner ear which contains the sense organs of hearing. | Organ of Corti |
| A structure lying within the protoplasm of a cell and performing a specific function. | Organelle |
| A chemical compound containing the element carbon. | Organic |
| Any carbohydrate, lipid or protein. | Organic Nutrient |
| An opening; an entrance to a cavity or tube. | Orifice |
| Diffusion through a semi permeable membrane. | Osmosis |
| The pressure that is established on one side of a semipermeable membrane as a result of the passage of a material through it. | Osmotic Pressure |
| A small bone, especially one of the three bones in the middle ear. | Ossicle |
| The process of bone formation. | Ossification |
| A cell concerned with the formation of bone. | Osteoblast |
| A cell which destroys bone to form channels through it for the passage of blood vessels and nerves. | Osteoclast |
