Large, complex cells (including animal and plant cells) with a cell membrane, cytoplasm and genetic material enclosed in a nucleus.

A cell acquires different sub-cellular structures to allow it to perform a certain function. (Differentiation results in the development of specialised cells).

Small, simple cells (including bacteria) with cytoplasm and a cell membrane surrounded by a cell wall. Their genetic material (a single DNA loop) is not enclosed in a nucleus. They may have small rings of DNA called plasmids.

The ability to see clear detail by distinguishing between two close points on an image.

A microscope which uses an electron beam (instead of light) to study cells in much finer detail. They have a much higher magnification and resolving power than a light microscope.

One copy of each chromosome (a chromatid) is pulled to each end of the cell and the nucleus divides. This is followed by the cytoplasm and cell membrane dividing to form two genetically identical cells.

of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

The diffusion of water molecules from a dilute solution to a concentrated solution, through a partially permeable membrane.

The net movement of particles (of any substance in solution, or particles of a gas) from an area of higher concentration to an area of lower concentration. Diffusion occurs down a concentration gradient.

Particles move from a dilute solution (lower concentration of particles) to a more concentrated solution (higher concentration of particles), through a partially permeable membrane. Particles move against a concentration gradient - this needs energy from respiration.

A biological catalyst that controls the rate of a chemical reaction inside a cell. Enzymes have an active site with a unique shape so that it can bind to a specific substrate molecule.

The shape of the active site of an enzyme has changed so that the enzyme no longer functions, because it can’t bind to its substrate.

Carbohydrases digest (break down) carbohydrates into simple sugars. Amylase is a carbohydrase which digests starch. Carbohydrases work in the mouth and small intestine.