Theory stating that all organisms are composed of cells, smallest unit of life is a cell and that all cells come from pre-existing cells.
Cell theory
The alteration of a cell's shape and function through gene expression.
Differentiation
A property of a system that does not appear in any of its component parts; e.g. brain (which thinks) is composed of many neurones (which don't).
Emergent property
An increase in physical size.
Growth
Process by which organisms maintain a relatively stable internal environment.
Homeostasis
The ratio of image size to actual size.
Magnification
All of the chemical reactions that occur within an organism or within a cell.
Metabolism
1/1000 of a mm
Micrometre (�m)
1/1000 of a metre
Millimetre (mm)
1/1000 of a �m
Nanometre (nm)
The part of the microscope that is nearest the object / specimen.
Objective lens
A single-celled organism. It moves using cilia and feeds using an oral groove.
Paramecium
Biological reductionism is the idea that you can explain complex processes by looking at the simple component parts.
Reductionism
A line on a microscope image which is labelled with the actual size of the line. From this the magnification can be calculated.
Scale bar
A degenerative eye disease that has been the target of stem cell research.
Stargardt's disease
Cells that divide and remain undifferentiated. Two types are totipotent and pluripotent.
Stem cells
A ratio that decreases as cells grow larger. Above a certain size cells do not have a large enough surface to exchange gases or nutrients to support the volume of the cell
Surface area to volume ratio
A level of organization that includes organs, tissues and cells.
System
A group of similar cells with a common function and structure.
Tissue
Response, growth, reproduction, excretion, nutrition, respiration, homeostasis.
Characteristics of living things